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The present study demonstrated that 5-HT(1A) receptor mRNA was expressed with moderate level in the NRM neurons. Most of 5-HT(1A) receptor mRNA positive cells were 5-HT neurons, suggesting the majority of 5-HT(1A) receptor in the NRM might be autoreceptors. Eight hours after carrageenan inflammation, the expression of 5-HT(1A) receptor mRNA in the NRM neurons, especially in the 5-HT neurons, was significantly increased. These results suggest that synthesis of 5-HT(1A) receptors, including 5-HT(1A) autoreceptors, is increased in the NRM during peripheral inflammation.

The level of serotonin (5-HT) and its major metabolite 5-hydroxyindoleacetic acid (5-HIAA) in dorsal horn of spinal cord and periaqueductal gray (PAG) were measured using in vivo microdialysis coupled with high performance liquid chromatography and electrochemical detection. Intraplantar injection of carrageenan was used to evoke release. Extracellular concentrations of 5-HT and 5-HIAA in spinal dorsal horn and PAG significantly increased following carrageenan inflammation. The peak occurred at 3h and then gradually returned to baseline at 5-7h. The carrageenan-induced release of 5-HT and 5-HIAA in spinal cord rather than in PAG was decreased by intracerebroventricular (i.c.v.) injection of naloxone, and both in spinal dorsal horn and PAG, the release was increased by i.c.v. injection of bicuculine. These results suggest that activity of 5-HT in spinal cord and PAG increases with carrageenan inflammation; the carrageenan-induced release of 5-HT and 5-HIAA in spinal cord may be tonically modulated by supraspinal opioid and GABA systems, whereas the release in PAG may only be tonically modulated by endogenous GABA system in supraspinal level.

In the present study we observed the expression of 5-hydroxytryptamine (5-HT)1A receptor mRNA in the dorsal raphe nucleus (DRN) and ventrolateral periaqueductal gray (vlPAG) neurons, especially in 5-HT immunoreactive neurons (5-HT-IR), using in situ hybridization (ISH) and double staining with fluorescent ISH (FISH) and immunohistochemical (FIH) techniques. The findings of this study demonstrated that 5-HT1A receptor mRNA was expressed with moderate to high level in the DRN and vlPAG neurons. Following carrageenan inflammation, the expression of 5-HT1A receptor mRNA in the DRN and bilateral vlPAG neurons was significantly increased. The peak occurred at 3-8h followed by a clear decrease at 24 h, which basically corresponded to the time-course of behavioral hyperalgesia. Moderate 5-HT1A receptor mRNA and 5-HT immunoreactive (5-HT-IR) double-labeled cells were observed in the DRN and vlPAG, suggesting that some of 5-HT1A receptors in the DRN and vlPAG may be autoreceptors. Eight hours after carrageenan injection, the number of the double labeled cells was significantly increased. These results suggest that the synthesis of 5-HT1A receptors, including autoreceptors, is increased in the DRN and vlPAG during peripheral inflammation.

A massive degeneration of dopamine-containing neurons in the substantia nigra (SN) in the midbrain is characteristic of Parkinson's disease. Inflammation in the brain has long been speculated to play a role in the pathogenesis of this neurological disorder. Recently, we reported that treatment of primary rat mesencephalic mixed neuron-glia cultures with lipopolysaccharide (LPS) led to the activation of microglia, resident immune cells of the brain, and subsequent death of dopaminergic neurons. The LPS-induced degeneration of dopaminergic neurons was significantly attenuated by the opiate receptor antagonist (-)-naloxone and its inactive isomer (+)-naloxone, with equal potency, through an inhibition of microglial activation and their production of neurotoxic factors. In this study, injection of LPS into the rat SN led to the activation of microglia and degeneration of dopaminergic neurons: microglial activation was observed as early as 6 h and loss of dopaminergic neurons was detected 3 days after the LPS injection. Furthermore, the LPS-induced loss of dopaminergic neurons in the SN was time- and LPS concentration-dependent. Systemic infusion of either (-)-naloxone or (+)-naloxone inhibited the LPS-induced activation of microglia and significantly reduced the LPS-induced loss of dopaminergic neurons in the SN. These in vivo results combined with our cell culture observations confirmed that naloxone protects dopaminergic neurons against inflammation-mediated degeneration through inhibition of microglial activation and suggest that naloxone would have therapeutic efficacy in the treatment of inflammation-related neurological disorders. In addition, the inflammation-mediated degeneration of dopaminergic neurons in the rat SN resulting from the targeted injection of LPS may serve as a useful model to gain further insights into the pathogenesis of Parkinson's disease.

To explore the site and mechanism of the analgesic action of melatonin, the present study was designed to evaluate the analgesic effects of intraperitoneal (i.p.) and intracerebroventricular (i.c.v. ) administration of melatonin, and to investigate the effect of i.c. v. naloxone on the analgesic effect induced by i.p. melatonin in rats. Antinociception was determined by tail-flick latency to hot water at 50 degrees C. On i.p. administration, melatonin (30, 60 and 120 mg/kg) produced the antinociceptive effect in a dose-dependent manner, with an A(50) of 72.8 mg/kg. Administered i.c.v., melatonin (0.25, 0.5 and 1 mg/kg) also resulted in dose-dependent antinociception, with an A(50) of only 0.693 mg/kg. Injected i.c.v. to rats, 10 microg of naloxone antagonized significantly the antinociceptive effect induced by i.p. melatonin. It is concluded that melatonin has an analgesic effect in rats and the central nervous system (CNS) may be the primary site for melatonin to elicit the response, and the effect of melatonin is related to the central opioid system.

Endogenous descending inhibitory system plays an important role in the modulation of nociceptive transmission. In recent years, descending facilitatory system has been noted. CNS bi-directionally modulates the peripheral nociceptive transmission at the spinal cord level via the descending inhibitory/facilitatory system. Serotonin (5-HT) is the main neurotransmitter in descending pain modulation. Intrathecal application of 5-HT or electrical stimulation or glutamate microinjection into the nucleus raphe magnus (NRM) and nucleus reticularis gigantocellularis(NGC) may produce inhibition and/or facilitation of spinal nociceptive transmission. The contradictory results may be attributed to the nonselective action(s) of 5-HT at multiple subtypes of 5-HT receptor in spinal cord.

The present study was undertaken to observe the effect of exogenously administered melatonin on the intensity of beta-endorphin (beta-Ep) immunoreactivity of the neuron in the arcuate nucleus of rat hypothalamus with an aim to explore the possible mechanisms of the analgesic effect of melatonin. The experimental rats were divided into two groups, one injected intraperitoneally with melatonin (110 mg/kg) and the other with only a vehicle. One hour after injection, the brain was processed for coronal sections, which were stained with immunohistochemical ABC technique. The integral optical density (IOD) and mean optical density (OD) of the stained sections were measured with a computer-assisted image-processing and analytical system. beta-Ep immunoreactivity was much decreased in the sections treated with melatonin and the IOD and OD were also decreased significantly (P<0.01; P<0.05). The above results suggest that melatonin may result in a decrease of beta-Ep content in the arcuate nucleus, as a result of increased beta-Ep release induced by administration of melatonin. It is likely that the analgesic effect of melatonin may be in part mediated by the release of beta-endorphin from the arcuate nucleus.

The present study was undertaken to explore central mechanisms underlying the analgesic effect of melatonin. Push-pull perfusion technique and radioimmunoassay were used to observe the changes in the contents of beta-endorphin (beta-Ep) and leucine-enkephalin (L-EK) in the perfusate from the rat periaqueductal gray (PAG) after administration of melatonin. 30 50 min after an intraperitoneal injection of melatonin (110 mg/kg), the beta-Ep content in the perfusate was increased significantly, while the L-EK content was not changed. Pain threshold was measured using the warm water tail-flick test during the push-pull perfusion of the PAG. It was found that the rat pain threshold was increased significantly 40 min after the intraperitoneal injection of melatonin (110 mg/kg). The results suggest that melatonin may promote the release of beta-Ep in the PAG, which may be one of the mechanisms of the analgesic effect of melatonin.

Aim: To observe altered expression of pro-opiomelanocortin (POMC) mRNA localized in neurons in the arcuate nucleus of rat hypothalamus following exogenous administration of melatonin., Methods: The experimental animals were divided into two groups injected i.p. with melatonin 90 mg.kg-1 and vehicle at 12 h interval (9:00 am and 9:00 pm). Twelve hours after the last injection, the rat brains were processed for coronal sections and nonradioactive in situ hybridization histochemistry technic was used. The integral optical density (IOD) and mean optical density (OD) of the stained brain sections were measured using the computer-assisted image processing technique., Results: The POMC mRNA expression in the arcuate nucleus showed obvious enhancement in the brain sections of rats treated with melatonin. The IOD and OD values in the hypothalamic arcuate nucleus area were increased significantly (P < 0.01, P < 0.05 respectively) with melatonin treatment., Conclusion: Melatonin may enhance the POMC mRNA expression in the arcuate nucleus of rat hypothalamus.

The present study was undertaken to assess the effects of intracerebroventricular (i.c.v.) luzindole (a selective MT(2) melatonin receptor antagonist) and prazosin (a selective MT(3) melatonin receptor antagonist) on melatonin-induced antinociception, so as to clarify which of melatonin receptor subtypes within the central nervous system (CNS) was mediating antinociception. The pain threshold of rats was measured by the hot water (50 degrees C) tail-flick test. It was found that intraperitoneal (i.p.) melatonin (30, 60, 120 mg/kg) resulted in a dose-dependent antinociception. Luzindole (50, 100 microgram) administered intracerebroventricularly antagonized significantly the antinociceptive effect induced by i.p. melatonin (120 mg/kg), whereas prazosin (50 microgram) did not. Neither luzindole (100 microgram, i.c.v.) nor prazosin (50 microgram, i.c.v.) affected the nociceptive threshold when given alone. The results suggest that melatonin-induced antinociception is mediated through the MT(2) melatonin receptor subtype within the CNS.

The present study was to investigate the dynamic changes of cellular immune function of rats with intrathecal injection of (ith) morphine and the regulatory effect of electroacupuncture(EA) stimulation on "Zusanli" (St.36) and "Lanwei" (Extra 37) points. The results showed that ConA-induced rat spleen lymphocyte proliferation was significantly decreased on 2h, 4h, 8h, 12h, 24h, 48h after ith morphine(40microg/50microL). The proliferative response was recovered to nearly normal on 72h. EA on corresponding periods could prevent the decrease of lymphocyte proliferative response of rats induced by ith morphine. The same tendency was observed on the induction of IL-2 production. Further study continued to explore the mechanism of the potentiating effect of mu-opioid receptor in periaqueductal gray (PAG) and hippocampus on the immunosuppression induced by ith morphine at molecular level with in situ hybridization histochemistry technique. The results showed that ith morphine could increase the expression of mu-opioid receptor mRNA.

The influence of morphine and EA on the apoptosis of thymocytes were studied to investigate the posibility of its involvement in the mechanism of morphine-induced immunosuppression and the regulatory effect of EA on it. 1h after injecting 50 mg/kg morphine subcutaneously into 3-wk old Balb/c mice continually twice a day for 5 days, thymus was collected and the apoptotic cell was detected by a method of terminal deoxynucleotidyl transferase-meditaed dUTP nick end-labeling(TUNEL). The results showed that morphine significantly enhanced the percentage of TUNEL positive cells inside thymus with an appearing of apoptotic DNA ladder after 24 h incubation. Treating mice with EA of "Zusanli(St.36)" and "Lanwei(Ext.33)" for 1h after morphine administration decreased the percentage of TUNEL positive cells. EA also showed an regulatory effect on the increased the expression of CPP32 and decreased the expression of Bcl-2 by morphine. The significant enhancement of hypothalamic CRF and plasma ACTH level by morphine and the antagonize effect of EA on it suggested a possible role of Hypothalamus-pituitary-adrenal (HPA) axis played in the apoptosis of thymocytes by morphine and the regulatory effect of EA.

Orphanin FQ (also known as nociceptin) is a 17-amino-acid peptide which acts as a potent endogenous agonist of the orphan opioid receptor-like (ORL1) receptor. Endomorphin-1, a 4-amino-acid peptide discovered recently, is a potent and selective endogenous agonist for the mu-opiate receptor. In the present study, the effect of OFQ or/and endomorphin-1 on the response to noxious thermal stimuli was observed using the tail-flick test in rats. Intracerebroventricular (i.c.v.) administration of OFQ (1, 5 microg) could shorten tail-flick latency; In contrast, intrathecal (i.t.) administration of OFQ (1, 2 or 10 microg) could increase the latency; i.c.v. (1, 2, 5 microg) or i.t. (0.2, 2, 5 microg) administration of endomorphin-1 dose-dependently increased the latency, indicating an analgesic effect. Furthermore, OFQ (0.1-5 microg) when intraventricularly injected together with endomorphin-1 (5 microg), could dose-dependently reverse the analgesia induced by the latter. On the contrary, OFQ (1 microg) intrathecally injected together with endomorphin-1 (0.2 microg) could further increase the tail-flick latency. The results showed that OFQ at the supraspinal level produces hyperalgesia and is antagonistic to endomorphin-1, while at the spinal level it produces analgesia and is synergic with endomorphin-1. Different interaction mechanism between OFQ and endomorphin-1 in the brain and the spinal cord is thus suggested., (Copyright 1999 Elsevier Science B.V.)

[Phe1psi(CH2-NH)Gly2]nociceptin-(1-13)-NH2, a pseudopeptide analog of nociceptin, was originally seen as an antagonist of nociceptin receptors. In the present study, it was observed that intracerebroventricular (i.c.v.) injection of this pseudopeptide (1, 5, 10 microg) significantly decreased the tail-flick latency of rats, indicating a hyperalgesic effect, while intrathecal (i.t.) injection of it (1, 2.5, 10 microg) dramatically increased the tail-flick latency, indicating an analgesic effect. This strengthened the in vivo evidence that [Phe1psi(CH2NH)Gly2]nociceptin-(1-13)-NH2 might be an agonist of nociceptin receptors.

Aim: To study the changes of monoamines in ventrolatoral periaqueductal gray of rat brain before and after electroacupuncture (EA) analgesia (EAA) was enhanced by fenfluramine (Fen), a 5-hydroxytryptamine (5-HT) releaser., Methods: Monoamines were collected by in vivo microdialysis and measured by HPLC connected with electrochemical detector., Results: The level of norepinephrine (Nor) after EA was decreased (P < 0.05 vs NS group). The contents of 5-HT, 5-hydroxyindol acetic acid (5-HIAA), dopamine (DA), and homovanillic acid (HVA) in periaqueductal gray dialysate were increased (P < 0.05 vs NS group). When Fen was combined with EA, the level of 5-HT and 5-HIAA were further increased (P < 0.05 vs NS + EA group). There was no obvious change of Nor, DA, and HVA., Conclusion: Fen potentiating EAA may be related to further activation of serotoninergic system.

The effect of methionine-enkephalin (ME) on glial neurotrophic function was studied in rat cortical glial-neuronal coculture. The results showed that ME-treated glia enhanced neuronal survival by 28% (P < 0.05), and increased total neurite length per neuron by 11% (P < 0.05), while the expression of GAP-43 mRNA by 26% (P < 0.05). The effect of ME on NO production of glia was also studied in rat cortical glial culture. The result showed that different concentrations of ME (10(-12), 10(-10), 10(-8), 10(-6) mol/L) inhibited glial NO production. All the above show that the increase of glial neurotrophic ability by ME may be due to the inhibition of glial NO production.

Nociceptin/orphanin FQ (nociceptin/OFQ), a newly discovered heptadecapeptide has been regarded as an endogenous ligand for orphan opioid receptor. The present study was designed to investigate the effect of nociceptin/OFQ on pain response and opioid analgesia in the rat formalin test. The results showed that intracerebroventricular injection of 1 microg nociceptin/OFQ enhanced the pain response, and 0.1 or 0.5 microg nociceptin/OFQ had no effect on formalin-induced pain. When 0.1 or 1 microg nociceptin/OFQ were used together with mu-, delta-, or kappa-opioid receptor agonists, endomorphin-1, DSLET or U50488H, respectively, it attenuated mu- and kappa- but not delta-receptor mediated analgesia. On the other hand, intrathecal injection of nociceptin/OFQ (0.1, 1 and 5 microg) reduced the pain response in the formalin test. In conclusion, nociceptin/OFQ potentiated formalin-induced pain response and antagonized opioid analgesia in the rat brain but inhibited pain response in the spinal cord.

Previous studies have shown that dopamine (DA) is involved in electroacupuncture analgesia (EAA). L-tetrahydropalmatine (l-THP), a DA receptor antagonist was proved to potentiate EAA in both laboratory research and clinical practice. In the present study SK&F-38393 and quinpirole (Qui), selective agonists of D1 or D2 receptors respectively were injected into nucleus (N.) accumbens of rats to investigate the roles of D1 and D2 receptors in the potentiation of EAA induced by l-THP. The injection of D1 agonist SK&F-38393 (5 microg or 10 microg) attenuated the potentiation of EAA induced by l-THP, 10 microg SK&F-38393 attenuated EAA as well, while the injection of D2 agonist Qui (10 microg or 20 microg) had no effect on EAA and the potentiation of EAA induced by l-THP. DA release was shown to increase in EAA in previous work, however, whether the synthesis of DA was influenced is still unknown. In the present study, dot blot technique was applied to observe the effect of noxious stimulation or electroacupuncture on the level of tyrosine hydroxylase (TH) mRNA in rat brain. Noxious electric stimulation was found to elevate the TH mRNA level in substantia nigra (SN) and hypothalamus, while electro-acupuncture attenuated the effect of noxious stimulation on TH mRNA. The results indicate that D1 but not D2 receptor in N. accumbens plays an important role in EAA. EA might regulate the biosynthesis of DA by altering the TH gene transcription.

The present study was undertaken to examine the effects of intracerebroventricular (icv) injection of naloxone (an antagonist of opioid receptors) and electroacupuncture (EA) on the natural killer (NK) cell activity, lymphocyte proliferation and induction of interleukin-2 (IL-2) production of spleen lymphocytes of surgically traumatized rats. The NK cell activity, the spleen lymphocyte proliferation and the induction of IL-2 production were all significantly inhibited following traumatization. Compared to the traumatic group, the inhibition of the NK cell activity and the induction of IL-2 production were antagonised by icv injection of naloxone. EA stimulation of Zusanli (St 36) and Lanwei (Extra 33) points reduced the immunosuppression produced by trauma. The above results show that the central endogenous opioid peptidergic system may play an important role in immunosuppression. It is suggested that the endogenous opioid peptidergic system might act as an important modulatory system between CNS and the immune system.

Aim: To study the involvement of opioid receptor of periaqueductal gray (PAG) and hypothalamic-pituitary-adrenal (HPA) axis in the effect of intrathecal morphine on immune function., Methods: Rat splenic natural killer (NK) cell activity was determined by a europium release assay; the concanavalin A-induced splenic IL-2 production, TNF-beta activity, and serum TNF-alpha level were determined by colorimetric thiazolyl blue tetrazolium bromide (MTT) and gentian violet assay, and serum corticotrophin (ACTH) level by radio-immunological method after intrathecal injection of morphine and PAG microinjection of naloxone., Results: Intrathecal morphine inhibited splenic NK cell activity, IL-2 production, TNF-beta activity, and increased in serum ACTH level. Microinjection of naloxone 1 microgram into PAG partially antagonized the inhibition of NK cell activity and the elevation of serum ACTH level by morphine., Conclusion: The opioid receptor of PAG involved in the suppression of NK cell activity by intrathecal morphine, which was accompanied by an activation of HPA axis.

The aim of this study was to investigate the distribution of a calcium-inhibitable adenylyl cyclase type VI (type VI AC) in the central nervous system using an antiserum directed against the N-terminus of type VI AC. Our results indicate that type VI AC immunoreactivity is generally expressed in many brain regions with different levels of intensity. Most interestingly, the majority of the detected type VI AC immunoreactivity is present in cells of neuronal phenotype. Double immunostaining of type VI AC and markers of various neurotransmitter systems suggest that type VI AC might participate in regulation of the classical neurotransmitter systems and therefore appeared to play a very important role in the central nervous system.

Orphanin FQ (OFQ) is a newly-discovered neuropeptide which shares great similar sequence with endogenous opioid peptide but with different functions. The present study was to investigate the role of OFQ microinjected in the periaqueductal gray (PAG) on pain threshold and acupuncture analgesia (AA) using tail flick tests. The results show that the hyperalgesia of OFQ and its antagonization on AA in PAG are dose-related. OFQ in PAG decreases the enhancing effect on AA induced by ohmefentanyl, a selective mu-receptor agonist. These observations suggest that OFQ in PAG can increase the rat pain sensitivity and antagonize AA.

Some selective dopamine receptor agonists and antagonists were tested on rat tail flick model to investigate the role of D1 and D2 dopamine receptor in pain and acupuncture analgesia (AA). It was found that intrathecal administration (i.t.) of D2 receptor agonist LY171555 or D1/D2 receptor agonist apomorphine increased pain threshold and had a potentiating effect on AA. In contrast, D1 receptor agonist SKF38393 had no effect. It D1 receptor antagonist SCH23390 or D2 receptor antagonist sulpiride attenuated the effect of AA. The results suggest that D2 receptor is involved in pain modulation and activation of D2 receptor and enhances AA in the spinal cord, while such effect is absent in D1 receptor and inactivation of D1 receptor attenuates AA.

Aim: To study the effect of orphanin FQ (OFQ), a newly discovered heptadecapeptide, on nociception and opioid analgesia., Methods: The intracerebroventricular (i.c.v.) and intrathecal (i.t.h.) injections were used to give the drugs. The tail-flick model of rats were used to test the pain threshold., Results: OFQ (i.c.v. or i.t.h.) 0.1 microgram had no effect on nociception but 0.5-10 micrograms induces hyper-reaction of rat to noxious electric stimulus; the decapeptide (OFQ1-10 i.c.v.), a fragment of the OFQ, did not affect the pain reaction of rats. Fentanyl (1 microgram, i.c.v. or i.t.h.), a selective mu-receptor agonist, DSLET (5 micrograms, i.c.v. or i.t.h.), a selective delta-receptor agonist, or U50488H (1 microgram, i.t.h.), a kappa-receptor agonist, induced an increase in pain threshold, when OFQ (0.1 or 1 microgram) was added together with one of them (except for the ith injection of DSLET), the increase of pain threshold was reduced obviously., Conclusion: OFQ induces hyperalgesia and antagonizes opioid analgesia mediated by mu- and delta-receptors in the brain and by mu- and kappa- but not delta-receptors in the spinal cord of rats.

The present study was to observe the dynamic changes of tyrosine protein kinase (TPK) activity in subcellular fractions in the early stage of activation of T lymphocytes from normal and traumatized rats, and the regulatory effect of electroacupuncture (EA) stimulation on it. The results showed that the activities of TPK in membranous and cytosolic fractions of activated T lymphocytes were increased on second 5, and the peak was on scond 45 after ConA stimulation. Then it was decreased gradually. Comparing with the control group, the activities of TPK in membranous and cytosolic fractions of activated T lymphocytes from the traumatized rats were inhibited in various degrees especially in membrane. EA of "Zusanli"(ST-36) and "Lanwei"(Extra 33) points could enhance the activity of TPK in subcellular fractions of activated T lymphocytes from the traumatized rats. The results indicated that EA stimulation could prevent the inhibition of activation of TPK induced by trauma stress, and contribute to transmembrane signal transduction of T lymphocytes.

Orphanin FQ(OFQ) is a recently discovered 17-amino acid neuropeptide[1-2]. In present paper, influence of intracerebroventricular(ICV) administration of OFQ or electroacupuncture(EA) on the surgical trauma-induced inhibition of the splenic natural killer(NK) cell activity in rat was observed. The results showed that administration of 0.1 microgram(0.0055 nmol) and 1 microgram (0.055 nmol) OFQ had no effect on the NK cell activity, while 5 micrograms(2.75 nmol) OFQ reduced the NK cell activity in normal rats. However, 0.1 microgram, 1 microgram or 5 micrograms OFQ were found to antagonise the immune function depression caused by surgical trauma. The NK cell activity was reduced in normal rats after repeated ICV treatment with antisense oligonucleotide (ASO) complementary to bases of translated region of rat OFQ receptor mRNA to block the translation of OFQ receptor mRNA into protein. EA stimulation of Zusanli(St. 36) and Lanwei(Extra. 37) points also obviously improved the immunosuppression produced by trauma. OFQ combined with EA showed antagonism on the suppression, but there was no significant differences compared with OFQ(ICV) or EA alone. When blocking the translation of OFQ receptor mRNA with the ASO, the OFQ induced anti-immunosuppression effect was completely reversed, but EA still improved the inhibition on NK cell activity. The results suggested that the OFQ played a role in the regulation of immunosuppression. EA could modulate the suppression of NK cell activity induced by surgical trauma. The mechanisms of the modulation of OFQ or EA on the immunosuppression induced by surgical trauma need further study.

The present paper is to study the effects of electroacupuncture (EA) on acute ischemic stroke patient and acute cerebral ischemic rat. In clinic, 42 acute ischemic stroke patients were randomly divided into 2 therapeutic groups: drug group and EA+ drug group. Neurological deficits of patients were evaluated before and after the treatment by Chinese Stroke Scale. The results showed that the acute ischemic stroke patients treated by drug or EA+ drug were all partially recovered, but the clinical functional recovery in EA+ drug group was significantly better than in the drug group (P < 0.01). In laboratory, the model of reversible middle cerebral artery occlusion (MCAO) was used in rats. The somatosensory evoked potential (SEP) was recorded before and after MCAO. EA was applied one hour after cerebral ischemia and once a day after reperfusion for 7 days in EA+ MCAO group. It was shown that the amplitude of P1-N1 wave of SEP before MCAO was 100%. After MCAO 30 min the P1-N1 wave of SEP on the ipsilateral side of MCAO was decreased to 2.2 +/- 3% (MCAO group), 1.9 +/- 2% (MCAO+ EA group); and then recovered to 25.5 +/- 14.1% (MCAO group), 58.6 +/- 27.2% (MCAO+ EA group) after 7 days of reperfusion following MCAO 2 hours. The above results indicated that EA could promote the recovery of neurological function in acute ischemic stroke patients and SEP on MCAO rats.

Aim: To study the roles of dopamine (DA) D1 and D2 receptors in nucleus accumbens in electroacupuncture analgesia (EAA) and the potentiation of EAA of rats induced by l-tetrahydropalmatine (l-THP), a dopamine receptor antagonist., Methods: SK&F-38393 and quinpirole hydrochloride (Qui), highly selective agonists of D1 and D2 receptors, respectively were injected into nucleus accumbens of rats., Results: SK&F-38393 (5 and 10 micrograms) attenuated the potentiation of EAA induced by l-THP, 10 micrograms SKF38393 attenuated EAA as well, while Qui (10 and 20 micrograms) had no effect on EAA and the potentiation of EAA induced by l-THP., Conclusion: D1 but not D2 receptor in nucleus accumbens play an important role in EAA and the potentiation of EAA induced by l-THP.

The present study was designed to observe the effect of orphanin FQ (OFQ, also known as 'nociceptin'), a newly-discovered neuropeptide, on pain behavior and morphine analgesia evaluated by formalin test in rats. It was found that intracerebroventricular (i.c.v.) injection of 0.1 microg OFQ had no effect on formalin-induced pain behavior; but 1, 5, 10 or 20 microg OFQ produced prolonged lifting, licking, biting or shaking of the affected paw with higher pain scoring in dose dependent manner. Repeated i.c.v. injection of antisense olignucleotide (ASO) complementary to OFQ receptor but not mismatch olignucleotide (MSO) resulted in the decrease of pain behavior; in such circumstances, OFQ showed no enhancing effect on formalin nociception. OFQ (0.1 or 1 microg, i.c.v.) significantly attenuated morphine analgesia and ASO could validly antagonize the effect of it. Pretreatment with MSO had no such effect. The present results suggest that OFQ enhances the pain behavior of rat and antagonizes morphine analgesia in formalin test.

Orphanin FQ (OFQ) is a newly discovered 17-amino-acid peptide capable of inducing hyperalgesia. In the present study, the effects of OFQ on basal pain threshold and acupuncture anlgesia (AA) in rats were observed using the tail-flick test. It was found that intrathecal (i.t.) or intracerebroventricular (i.c.v.) administrition of 0.1 microgram OFQ had no effect on basal pain threshold of rats, while 1 microgram OFQ could lower the threshold. However, OFQ at both the doses (0.1 or 1.0 microgram) administered by either i.t. or i.c.v. injection could antagonize AA with that occuring in the brain being more prominent then in the spinal cord. When the rats were repeatedly treated with antisense oligonucleotide to block synthesis of OFQ receptor, pain threshold increased significantly. At such instance, when the OFQ was combined with acupuncture, the effect of AA showed no obvious change. The above results show that the OFQ at small dose has no effect on pain threshold but can lower it at larger dose; while in both cases OFQ can antagonize AA.

The monoamine contents in microdialysate from rat brain before and after droperidol (DRO), a dopamine (DA) antagonist, enhanced electroacupuncture-induced analgesia (EA) were measured using techniques of in vivo microdialysis and high performance liquid chromatography with electrochemical detection (HPLC-EC), so as to investigate the monoamine mechanism of the potentiating effect of DRO on acupuncture analgesia (AA). The results showed that the levels of DA and its metabolites homovanillic acid (HVA) in perfusate increased after EA (P < 0.05 or 0.01), and further increased after DRO + EA (P < 0.05 and 0.01, vs EA treatment). A significant decrease in norepinephrine (NE) content after EA (P < 0.01) was observed, but no further change after DRO + EA (P > 0.05, vs EA treatment). The contents of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) we elevated after EA treatment, and a further elevation in 5-HT and 5-HIAA contents induced by DRO + EA was noted. The results in the present study suggest that DRO potentiated AA not only via antagonizing the activity of dopaminergic system, but also by coordinating the activities of other monoamines in the brain.

Endothelin-1 (ET-1), which is secreted from vascular endothelial cells, is not only a potent vasoconstrictor but also a vascular smooth muscle cell growth factor. The direct effect of ET-1 on vascular smooth muscle cells, mediated via its specific receptor may therefore play an important role in hypertension and atherosclerosis. Our previous studies indicated that ET-1 secretion from cultured aortic endothelial cells from spontaneously hypertensive rats (SHRs) at the prehypertensive stage (4 weeks old) was not significantly different from that of cells from age-matched Wistar-Kyoto (WKY) rats. In this study, the binding of ET-1 to cultured aortic smooth muscle cells from SHRs and WKY rats was studied. Using tissue explant techniques, rat aortic smooth muscle cells from SHRs and age-matched WKY rats of different ages (4 and 24 weeks old) were successfully cultured in vitro. The maximum binding capacity (Bmax) and binding affinity (Kd) of ET-1 to cultured aortic smooth muscle cells were evaluated by a receptor-binding assay. The data revealed that the affinity of ET-1 binding to smooth muscle cells was similar in all 4 groups of experimental rats. However, the Bmax of cultured smooth muscle cells from 24-week-old SHRs was 2.5 times higher than of smooth muscle cells from age-matched WKY rats (8.64 +/- 0.72 vs 3.69 +/- 0.10 fmol/10(6) cells) and 1.5 times higher than in aortic smooth muscle cells from 4-week-old SHRs (8.64 +/- 0.72 vs 5.36 +/- 0.36 fmol/10(6) cells). These results suggest that hypertension in SHRs may be related to a high density of ET-1 receptors on arterial smooth muscle cells.

The present study was to investigate the dynamic changes of the induction of interleukin-2 (IL-2) production of spleen lymphocytes from the rats after operative trauma stress and the regulatory effect of continued electroacupuncture (EA) stimulation of "Zusanli" (St. 36) and "Lanwei" (Extra 33) points on the induction of IL-3 production of spleen lymphocytes from the injured rats. The results showed that the induction of IL-2 production of the rat spleen lymphocytes was significantly decreased on day 1, 3, 5, 7 (P < 0.05), and the minimum level was on day 3 after operative trauma at both dilution 1:8 and dilution 1:16. The induction of IL-2 production was reserved to nearly normal on day 10. Continued stimulation by EA on "St. 36" and "Extra 33" points on day 3, 5, 7 increased the induction of IL-2 production in various degrees at the two dilutions (P < 0.01), or P < 0.05). The results mentioned above implied that the immune function could be depressed by trauma stress. Continued EA stimulation could improve the immunosuppression induced by trauma stress.

Possible synergistic effects of the glucocorticoid dexamethasone (DEX, 10(-7) M) and the adenylate cyclase agonist forskolin (FSK, 10(-5) M) on [Met5]enkephalin (ME) accumulation were examined in enriched rat glial cultures and in mixed neuronal/glial cultures. In enriched glial cultures, DEX and FSK each stimulated the accumulation of ME 2-3-fold over basal media levels, but there was little additional stimulation when these agonists were combined. In contrast, mixed neuronal/glial cultures showed only weak responses to DEX or FSK alone, but the combination of these agonists produced a pronounced synergistic effect on media ME accumulation (6-10-fold over basal levels). The DEX effect was mediated via a classical glucocorticoid receptor, since DEX was potent (acting over a concentration range of 10(-11)-10(-7) M), mimicked by corticosterone (10(-6) M), and blocked by the glucocorticoid receptor antagonist RU486. There was a pronounced time lag (2 days) for the synergistic effects of DEX + FSK to develop. In situ hybridization and immunocytochemical studies suggested that astrocytes were the major source for the increased ME production in all mixed neuronal/glial cultures examined. Creating a mixed culture by plating fetal neurons onto confluent, enriched P7 glial cultures inhibited accumulation of ME in the media. DEX + FSK, but neither agonist alone, overcame this neuronal inhibition and increased accumulation of media ME to levels identical to levels in stimulated enriched glial cultures. The net effect was a 6-fold increase in ME accumulation in the mixed neuronal/glial cultures relative to a 2.5-fold increase in the enriched glial cultures. Neuronal inhibition of basal glial ME production could explain the similar synergistic effects of DEX + FSK observed in all mixed neuronal/glial cultures examined, and may be important in suppressing ME production by astrocytes in the brain.

The influence of orphanin FQ (OFQ) (a newly discovered 17-amino acid peptide) on acupuncture analgesia (AA) was assessed in rat tail-flick model. Intracerebroventricular (i.c.v.) injection of OFQ (1 microgram) elicited a significant decrement of pain threshold which was abolished by the repeated pretreatment with antisense oligonucleotide (ASO) to OFQ receptor. Electroacupuncture (EA) induced an obvious analgesic effect; when OFQ was used combined with EA, it showed a dose-dependent effect on antagonizing the EA analgesia. When rat was repeatedly i.c.v. injected with ASO to block the synthesis of OFQ receptor, the EA analgesia was enhanced markedly. In this instance, the OFQ did not show antagonistic effect on EA analgesia any more. The results suggest that the OFQ play its antagonistic role on EA analgesia via activating OFQ receptor.

Dopaminergic neurotoxicities of 6-hydroxydopamine (6-OHDA) and the lipopolysaccharide (LPS) were compared in rat mesencephalic cultures plated on poly-L-lysine or on glial monolayers. In the neuron-enriched cultures plated on polylysine, 6-OHDA killed 89% of the tyrosine hydroxylase (TH)-immunopositive neurons, but LPS was not neurotoxic. Conversely, in mixed neuron/glial cultures, 6-OHDA killed only 27% of the TH-immunopositive neurons while LPS killed 70%. The mixed neuronal/glial mesencephalic culture offers a better in vitro model for studying possible mechanisms involved in Parkinson's disease.

The effects of nicotine on the transcriptional activity of the proENK gene, proenkephalin A (proENK) mRNA levels, and the secretion of [Met5]-enkephalin (ME) were studied in bovine adrenal medullary chromaffin (BAMC) cells. Nicotine (10 microM) caused an immediate secretion (within 1 hr) of ME followed by a delayed secretion (12-24 hr after treatment) into the medium. Posttreatment with the cholinergic antagonists, hexamethonium (1 mM) and atropine (1 microM), up to 6 hr after the nicotine treatment significantly inhibited the delayed secretion of ME induced by nicotine. However, nicotine-induced long-term secretion of ME was not affected when cholinergic antagonists were added 9 or 12 hr after the nicotine treatment. Long-term (24 hr) stimulation of BAMC cells with nicotine also increased proENK mRNA level. This nicotine-induced response was inhibited by posttreatment with cholinergic antagonists 0.5, 1, 3 and 6 hr after the nicotine treatment. As with the secretion experiments, these cholinergic antagonists did not affect the nicotine-induced responses when they were added at 9 and 12 hr. Posttreatment with nimodipine (1 microM), calmidazolium (1 microM) or KN-62 (5 microM) up to 6 hr after the nicotine treatment significantly inhibited the increases of the long-term secretion of ME and proENK mRNA level induced by nicotine. However, these agents were ineffective in blocking the long-term secretion of ME and proENK mRNA level induced by nicotine when BAMC cells were posttreated after 9 and 12 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

The present study was to trace the neuronal pathway in the spinal cord and brainstem following noxious stimulation and acupuncture plus noxious stimulation by using immunohistochemical technique to detect the expression of c-fos like protein. The results showed that in both the noxious stimulation group and acupuncture of Zusanli(St.36) and Lanwei(Extra 33) points plus noxious stimulation group a lot of Fos-like immunoreactive (FLI) cell nuclei appeared in the following structures: dorsal horn of lumbar and sacral spinal cord (Laminae I, II, V and X), n. reticularis lateralis, n. reticularis paragigantocellularis lateralis, area A1, n. tractus solitarii, n. raphe magnus, locus coeruleus, n. raphe dorsalis and the periaqueductal grey. In the control group no obvious c-fos expression was shown in the structures mentioned above. It was also shown that in the lumbar and sacral spinal cord the number of FLI nuclei in the acupuncture plus noxious stimulation group was more than that in the noxious stimulation group, but in locus coeruleus and the ventral part of the periaqueductal grey the number of FLI nuclei in the acupuncture plus noxious stimulation group was less than that of the noxious stimulation group. The results imply that acupuncture and noxious stimulation may activate the intrinsic pain modulating system through the spinal dorsal horn, then suppress the c-fos expression induced by noxious stimulation in the locus coeruleus and ventral part of the periaqueductal grey.

The present study was to investigate the role of the RPGL and its endogenous opioid peptides in acupuncture analgesia (AA) using techniques of brain stimulation and lesion, microinjection, push-pull perfusion and radioimmunoassay (RIA). The results showed that electrical stimulation of the RPGL could increase the pain threshold and enhance the effect of AA, whereas lesion of the RPGL reduce the effect of AA. Microinjection of naloxone (5 micrograms/0.5ul/2min) into the RPGL could partially reverse the effect of AA and the reversal effect of naloxone was dose-dependent. The release of leu-enkephalin (LEK) and B-endorphin (B-EP) from the RPGL in the electrical acupuncture (EA) group was significantly higher than that in the control group (P < 0.05). There were positive correlations between the changes of release of LEK, B-EP and the increase of pain threshold. The results mentioned above imply that the RPGL plays an important role in AA. The activation of the RPGL and the endogenous opioid peptides within it produce an advantageous effect on AA.

The present work was to study the roles of opioid peptides in the preoptic area on electroacupuncture analgesia (EA), and the effects of opioid peptides on noradrenaline (NA) release in the preoptic area during EA. It was found that the pain threshold and the level of [Leu5] enkephalin (L-EK) or beta-endorphin (beta-EP) release in the perfusate were increased during EA, but the NA release from the preoptic area was decreased. Naloxone (15 microM) perfusion significantly reversed the increased pain threshold and the decreased NA release induced by acupuncture. The reversal of pain threshold and the decreased NA release induced by acupuncture. The reversal of pain threshold and NA release by naloxone was dose-dependent. Multimicropipettes and microiontophoresis were also used to study the effect of acupuncture. The inhibition of nociceptive neuronal discharges produced by electroacupuncture was closely related to the etorphine-sensitive neurons, and reversed by microiontophoretic application of naloxone. The results suggest that the inhibitory effect induced by electroacupuncture may be mediated by opioid peptides in the preoptic area.

Regulation of tyrosine hydroxylase (TH) by second messenger pathway activators was examined in rat olfactory bulb cell cultures. The number of TH-immunoreactive neurons was increased 2-3-fold by 36 h treatments with forskolin (Fsk, 10(-6) M) or phorbol myristate acetate (PMA, 10(-7) M), but was not significantly increased by a depolarizing concentration of KCl (45 mM). In contrast, KCl increased media [Met5]enkephalin (ME) immunoreactivity 2-fold in these cultures, equivalent to stimulation with Fsk or PMA. The possibility was examined that ME or another opioid produced by the cultures selectively inhibited the TH response to KCl. Pretreatment with the opioid receptor antagonist naloxone (10(-6) M) greatly increased the number of TH-immunoreactive neurons observed in response to KCl treatment, but had no effect on basal or Fsk-stimulated TH immunostaining, nor on basal or stimulated ME release. The increase in TH-immunoreactivity observed with combined KCl plus naloxone treatment was prevented by pretreating the cultures with the calcium channel blocker nimodipine (10(-6) M), which had no effect on Fsk stimulation or basal TH immunostaining. These data suggest that endogenous opioids selectively inhibit KCl-stimulated Ca2+ entry and thus TH induction in olfactory bulb cell cultures. These cultures offer a simple model system for further study of TH regulation in dopaminergic neurons.

By push-pull perfusion technique and RIA of neuro-peptides, it was found that after 20 minutes' electroacupunture (EA), the release of LEK from the RPGL in the EA group was significantly higher than that in the control group (P < 0.05). The release of beta-EP from the RPGL in the EA group with higher efficacy was significantly higher than that in the control group (P < 0.05), but no significant changes were found in the EA group with lower efficacy. There was a positive correlation between the changes of release of LEK or beta-EP and the increase of pain threshold. The release of DynA1-13 tends to show a barely significant extent (P > 0.05). The results indicate that acupuncture analgesia is able to increase the release of LEK and beta-EP in the RPGL.

Cortical potentials evoked by stimulation of the contralateral tooth-pulp were recorded epidurally from the SI cortex of rabbits anesthetized with urethane and chloralose. It was found that nociceptive components of the evoked potential consisted of P1 and P2 wavelets with a relative stable peak latency of 22.5 +/- 1.2 ms and 66.1 +/- 1.9 ms respectively. Higher intensity of tooth pulp stimulation was required for appearance of P2 than P1. Diazepam, a non-analgesic sedative, reduced P1 but not P2 amplitude. On the contrary, dolantin, an analgesic, suppressed P2 but showed no significant influence on P1. The results suggest that P2, but not P1 might be related to pain. The effects of l-tetrahydropalmatine (1-THP) and electroacupuncture on P2 were observed on 12 animals. The results showed that both iv l-THP 8mg/kg and electroacupuncture brought forth a decrease in P2 amplitude by 40.3 +/- 14% and 59.3 +/- 10% respectively, while electroacupuncture combined with l-THP produce a further decrease in P2 amplitude by 92.8 +/- 7%. Furthermore, the inhibitory periods of P2 amplitude were significantly prolonged after electroacupuncture combined with l-THP. The results indicated that l-THP enhanced the suppression of P2 by electroacupuncture.

The effects of icv 4 dopamine (DA) agonists on analgesia caused by iv l-tetrahydropalmatine (THP) 8 mg/kg or by electro-acupuncture (EA) were studied by using the potassium iontophoretic dolorimetry in rabbits. The results showed that both THP-induced analgesia and EA analgesia were markedly attenuated by icv of DA or apomorphine (Apo), 2 mixed D1/D2 agonists. Similar results were obtained when SKF-38393, a selective D1 agonist, was applied. On the contrary, quinpirole hydrochloride (Qui), a selective D2 agonist, was found to enhance the analgesic action of THP or EA. However, DA, Apo, SKF-38393 or Qui per se did not influence the baseline pain threshold. All these observations indicate that functional alterations in DA receptor activities may be involved in THP-induced analgesia and EA analgesia, in which D1 and D2 subtype receptors exert different roles.

l-Tetrahydropalmatine (l-THP), tetrahydroberberine (THB) and l-stepholidine (l-SPD) are the homologues of tetrahydroproto berberines and have a common antagonistic effect to central dopamine receptors. In the present experiment, the potassium iontophoretic dolorimetry was used to determine the pain threshold of rabbits. Unilateral "Hegu" point (the dorsum of the front paw, between 1st and 2nd metacarpals) and "Waiguan" point (the dorsum of the foreleg, between radius and ulna, 2 cm above the wrist joint) of each rabbit were electrically needled. The effects of iv l-THP 8 mg/kg, THB 16 mg/kg or l-SPD 4 mg/kg on electroacupuncture analgesia were investigated. The experimental results indicated that these 3 agents enhanced the potency of electroacupuncture analgesia and prolonged the duration as well. This investigation gives the evidence that the drug possessing antagonistic effect to central dopamine receptors could be used as a synergist of acupuncture analgesia.