Search

Nutrition support with parenteral nutrition (PN) is associated with gut atrophy. Prior studies have shown improvement with enteral chenodeoxycholic acid, a dual agonist for the farnesoid X receptor (FXR) and bile acid receptor TGR5. We hypothesized that gut growth is induced by TGR5 activation, and gut atrophy during PN administration could be prevented with the TGR5-specific agonist oleanolic acid (OA).Neonatal pigs were implanted with duodenal and jugular vein catheters. Animals were provided equi-nutritious PN or enteral swine milk. A PN subgroup received enteral OA at 50 mg/kg/d.PN caused marked gut atrophy compared with enterally fed (EN) control animals. OA treatment led to preservation of gut mass demonstrated grossly and histologically. The mean ± SD gut weight as a percentage of body weight was 4.30 ± 0.26 for EN, 1.92 ± 0.06 for PN (P.05, EN vs PN), and 3.39 ± 0.79 for PN+OA (P.05, PN+OA vs PN). Mean ± SD gut density (g/cm) was 0.31 ± 0.03 for EN, 0.18 ± 0.03 for PN (P.05 EN vs PN), and 0.27 ± 0.01 for PN+OA (P.05 PN+OA vs PN). Histologically, a markedly decreased villous to crypt ratio was noted with PN, and OA significantly prevented this decrease. The mean ± SD v/c ratio was 3.51 ± 0.59 for EN, 1.69 ± 0.10 for PN (P.05, EN vs PN), and 2.90 ± 0.23 for PN+OA (P.05, PN+OA vs PN). Gut TGR5 messenger RNA expression was significantly elevated with OA treatment compared with both PN and EN.The bile acid-activated G protein-coupled receptor TGR5 agonist OA prevented gut atrophy associated with PN.

RET fused gene (RFG)/ELE1alpha/androgen receptor-associated protein 70(ARA70) was first found to be involved in the activation of the RET proto-oncogene in thyroid neoplasm and has recently been shown to be a ligand-dependent transcriptional coregulator for androgen receptor (AR). The functionality of RFG/ELE1alpha/ARA70 remains controversial, and little is known about factors regulating its expression in the prostate. Of significant interest is whether this molecule is involved in prostate carcinogenesis. Using reverse transcriptase-polymerase chain reaction semiquantitation, we compared RFG/ELE1alpha/ARA70 mRNA levels in four prostate cancer cell lines (LNCaP, TSU-Pr1, DU-145, and PC-3) with those found in primary cultures of normal prostatic epithelial cells (PrECs). In addition, we examined the effects of androgen and antiandrogen, estrogen and antiestrogen, and a demethylating agent on RFG/ELE1alpha/ARA70 mRNA expression levels in AR- and AR+ PC-3 cells. Reduced levels of RFG/ELE1alpha/ARA70 message were observed in all four prostate cancer cell lines when compared with normal PrECs in primary cultures. RFG/ELE1alpha/ARA70 mRNA levels in PC-3 cells, which express both estrogen receptor subtypes, were upregulated by 17beta-estradiol and inhibited by the antiestrogen ICI-182780. In PC-3(AR+) cells, which were genetically engineered to express AR, exposure to androgen upregulated RFG/ELE1alpha/ARA70 mRNA expression, whereas treatment with 4-hydroxyflutamide lowered expression of this transcript. Furthermore, treatment of DU-145 cells, which did not express RFG/ELE1alpha/ARA70 transcripts, with a demethylating agent reactivated transcription of this gene. Polymerase chain reaction analyses of monochromosomal human-rodent hybrid panels localized a putative RFG/ELE1alpha/ARA70 isoform on human chromosome 5q31.1-31.2. In summary, we identified sex hormones and DNA hypermethylation as regulators of RFG/ELE1alpha/ARA70 expression in prostate cancer cells. In addition, we found reduced levels of RFG/ELE1alpha/ARA70 expression in prostate cancer cell lines when compared with expression levels in normal PrECs in culture. These findings suggest that RFG/ELE1alpha/ARA70 may be involved prostate carcinogenesis and that it may serve as a key mediator of estrogen-androgen synergism.

In this article we review noradrenergic activities of nitroglycerin in the central and peripheral nervous systems. Nitroglycerin may cause paradoxical bradycardia and occasional life threatening hypotension in patients. Intracisternal injections and microinjections of nitroglycerin into nucleus tractus solitarii produce hypotension and bradycardia, effects which mimic the baroreflex and may involve central noradrenergic mechanisms. The drug also triggers an α 2 -adrenoceptor-mediated sympatho-inhibition reflex through vagal afferents. Nitroglycerin mimics biological responses associated with sympathetic neuronal activity, e.g., increase in outflow of norepinephrine and its metabolites from perfused guinea pig atria, medulla-pons tissue and cerebrospinal fluid. The sympathomimetic effects of nitroglycerin are antagonized by pre-treatment with yohimbine or rauwolscine. Clinical studies and animal experiments show that hemodynamics of nitroglycerin and sodium nitroprusside are different. Nitroglycerin is lipophilic and the compounds readily enters cells to form nitric oxide, but sodium nitroprusside is very hydrophilic and the compound has difficulty crossing membranes. Thus, intravenous nitroglycerin-induced increases in central noradrenergic activation and inhibitory reflexes may account for at least some of the therapeutic actions and side effects of the drug. In contrast, minimal central responses are produced by intravenous administration of sodium nitroprusside.

Nitroglycerin (NTG) may cause paradoxical bradycardia and occasional life-threatening hypotension. The mechanism is unclear. In this study, we compared the cardiovascular responses of sodium nitroprusside (SNP) with that of NTG in rats with sinoaortic deafferentation (SAD). Intravenous (i.v.) injection of SNP and NTG produced dose-dependent decreases in mean arterial pressure (MAP). SNP was more effective than NTG in increasing heart rate (HR). After SAD, tachycardiac responses to i.v. SNP were abolished, but i.v. NTG caused bradycardia. SAD enhanced the hypotensive responses of both NTG or SNP after i.v. administration. The bradycardic and hypotensive effects of NTG were attenuated by either bilateral vagotomy or intracisternal (i.c.) pretreatment with 20 nmol rauwolscine, but the responses were not altered by i.v. atropine methylbromide (M-atropine), 0.6 mumol. In contrast, cardiovascular responses to i.v. SNP after SAD were not altered by these pretreatments. Tachycardiac responses to intracerebroventricular (i.c.v.) injection of NTG were reduced by SAD, but SAD did not alter bradycardic responses to i.c. injection of NTG. These results suggest that NTG induces inhibitory reflexes that may contribute to its complex cardiovascular responses in rats. The drug may stimulate peripheral sensory receptors with vagal afferents to the medulla, which then triggers an alpha 2-adrenoceptor-mediated sympathoinhibition.

In order to facilitate identification of possible metabolites arising from in vitro action of catechol-O-methyltransferase upon 7,8-dihydroxy- and 8,9-dihydroxy-4-n-propyl-1,2,3,4,4a,5,6,10b-octahydrobenzo[f]quinolines (11, 12), all four possible monomethyl ether derivatives have been synthesized. Incubation of 11 and 12 with the enzyme revealed that the 8,9-dihydroxy positional isomer 12 (which contains the dopamine moiety held in the beta conformation) but not the 7,8-dihydroxy isomer 11 (which holds the dopamine moiety in the alpha conformation) was a substrate for the enzyme. The sole detectable product of 12 was 8-hydroxy-9-methoxy derivative 15 in which the "meta" hydroxy group of the dopamine moiety is etherified.

The subject compounds were prepared as a part of a continuing structure-activity study of the contrasting actions (agonism-antagonism) of (+)- and (-)-11-hydroxy-10-methylaporphine at serotonin (5-HT1A) receptors. None of the targeted nonoxygenated aporphine derivatives demonstrated significant activity in assays for any effects at serotonin 5-HT1A receptors. It is concluded that, in the aporphine series, serotonergic agonist or antagonism requires an alkyl group ortho to a phenolic OH group in the A ring.

Intracerebroventricular and i.v. administration of nitroglycerin in anesthetized Sprague-Dawley rats produced dose-dependent decreases in mean arterial pressure and increases in heart rate, but intracisternal injection of the drug induced hypotension and bradycardia. Hypotensive responses to intracisternal injection of nitroglycerin showed that the compound was two to three times more potent than by i.v. administration (six times when comparing the area under the curve). Intravenous sodium nitroprusside produced dose-dependent hypotensive and tachycardiac effects, but minimal responses were induced by i.c.v. and intracisternal injection. Central pretreatment with either yohimbine or rauwolscine antagonized hypotensive responses to i.c.v. and i.v. nitroglycerin, but did not alter the depressor responses induced by i.v. sodium nitroprusside. Tachycardiac responses to i.c.v. nitroglycerin are greater than the responses induced by i.v. administration. Inhalation of amyl nitrite produced marked hypotensive responses, with the dose-response curves being shifted to the right by i.c.v. pretreatment with rauwolscine, but not by i.v. pretreatment. The concentrations of 3,4-dihydroxyphenylglycol and 3-methoxy-4-hydroxyphenylglycol in cerebrospinal fluid were increased by i.v., i.c.v., and intracisternal administration of nitroglycerin, but were not altered by i.v. sodium nitroprusside. The concentrations of dihydroxyphenylacetic acid were elevated by i.v. and i.c.v. injection of nitroglycerin. Results suggest that nitroglycerin stimulates central noradrenergic activity, which may be involved in the component of hypotensive effects of the drug. Reflex tachycardiac responses to nitroglycerin may be further complicated by forebrain stimulation and medulla-mediated bradycardia. Sodium nitroprusside did not demonstrate central activity.

Sematilide is a new, non-quaternary class III antiarrhythmic agent currently undergoing clinical trials. We showed that a quaternary ammonium class III antiarrhythmic agent exhibits few extracardiac effects (Greenberg et al., Drug Dev. Res. 25.107–123, 1992). However, the extracardiac effects of a non-quaternary, pure class III antiarrhythmic agent are unknown. Sematilide, a pure class III antiarrhythmic agent, is effective in a canine model of arrhythmia at 0.3–1.0 mg/kg, intravenously (i.v.). We compared the nervous system and extracardiac effects of sematilide to acecainide (a class I/III) and several class I antiarrhythmic agents to evaluate the potential side effects of this new drug. Sematilide was devoid of neuropharmacologic activity in the mouse and rat, devoid of gastrointestinal activity in the mouse fed a charcoal meal, and without effect in the rat carrageenan-induced paw edema test. Ten to 30 times the average antiarrhythmic dose or plasma levels of sematilide were devoid of α1, muscarinic, nicotinic, and β-adrenoceptor blocking activities in a variety of preparations. Moreover, sematilide was devoid of depressant activity on (1) cholinergic, nicotinic, and sympathetic neurotransmission; (2) vascular and non-vascular smooth muscle reactivity and contractility; (3) aggregation of human platelets; (4) responses of the anesthetized dog to i.v. acetylcholine, isoproterenol, and nicotine; and (5) displacement of quinuclidinyl benzilate (QNB) binding to dog atrial membranes. Sematilide (10–30 mg/kg, i.v.) inhibited vagal nerve stimulation in the dog and slightly enhanced free water clearance in water-loaded dogs. The data show that effective antiarrhythmic doses and concentrations of sematilide are devoid of significant, injurious neural, hemodynamic, or smooth muscle side effects. © 1992 Wiley-Liss, Inc.

5-Methoxy-l-methyl-4-(2-N,N-di-n-propylaminoethyl)indole (12) was synthesized from 5-hydroxyindole by a multistep synthesis. This target compound was designed as a bioisostere of “p-dimethoxy” catechol congeners of dopaminergic agonists derived from a variety of ring systems, in some of which p-dimethoxy-substituted systems are potent, active dopaminergic agonists. To complete the indole series, all possible combinations of N- and O-demethylated derivatives of 12 were prepared and were also evaluated pharmacologically. All members of this indole-derived series showed a low order of cardiovascular activity, which appeared to be independent of dopamine receptors. The lack of dopaminergic activity of 12 is cited as yet another example of the unpredictable effect of replacement of the catechol moiety of a dopaminergic agonist with a p-dimethoxy moiety.

The studies show that unilateral microinjection of nitroglycerin (NTG) into nucleus tractus solitarii (NTS) produce dose-dependent decreases in mean arterial pressure (MAP) and heart rate, but injection of sodium nitroprusside (SNP) into the area induced slight effects. Hypotensive responses to NTG injected into the NTS showed that the compound was 20 times more potent than after i.v. administration. Responses to NTG injected into the NTS were abolished in an additive fashion by either rauwolscine, an alpha 2-adrenoceptor antagonist, or guanethidine which inhibits release of norepinephrine (NE). Injection of prazosin, an alpha 1-adrenoceptor antagonist, into the NTS reduced the hypotensive responses of NTG, but did not alter the bradycardia induced by the drug. Tachycardic responses following i.v. administration of either NTG or SNP were attenuated by bilateral injection of rauwolscine into the NTS, whereas only hypotensive responses to i.v. NTG were reduced by the pretreatment. NTG produced a dose-dependent increase in concentrations of 3,4-dihydroxyphenylalanine in media bathing medulla-pons, which were quantified using high-performance liquid chromatography with electrochemical detection. NE and 3,4-dihydroxyphenylglycol concentrations in media of incubated medulla-pons slices were simultaneously increased following higher concentrations of NTG. The results suggest that NTG in the NTS induces hypotensive and bradycardiac responses, and an increase in turnover of NE may stimulate alpha 2-adrenoceptors and be responsible for the effects of the drug. The NTS may contribute a component of action to the cardiovascular effects of intravenous NTG. The cardiovascular responses of intravenous SNP appear to involve peripheral action.

Nitroglycerin produced concentration-dependent increases in outflow of norepinephrine (NE) in perfused guinea-pig hearts. These effects of nitroglycerin were inhibited by guanethidine, but were not blocked by desmethylimipraminc or rauwolscine. Nitroglycerin-induced increases in NE outflow correlated with its positive chronotropic responses. Higher concentrations of nitroglycerin also increased outflow of 3,4-dihydroxyphenylglycol (DOPEG) which were inhibited by desmethylimipramine. Nitroglycerin-induced maximal outflow of NE occurred during the first 2 min, but maximal outflow of DOPEG was 2–4 min. In addition, the 3,4-dihydroxyphenylalanine formation in atrial and striatal slices were enhanced by nitroglycerin in the presence of m-hydroxybenzylhydrazine dihydrochloride (an inhibitor of aromatic L-amino acid decarboxylase). The results suggest that nitroglycerin increases release of NE which correlates with cardiac stimulation by the drug. The drug also stimulates tyrosine hydroxylase activity resulting in increased synthesis of NE.

The two enantiomers of the title compound have been prepared by different synthetic routes. Both bind strongly to 5-HT1A receptors from rat forebrain membrane tissue. However, in a guinea pig ileum preparation, the (R)-enantiomer exhibits properties consistent with its being an agonist, whereas the (S)-enantiomer shows no agonist effect, but it blocks the actions of the (R)-enantiomer and of 8-hydroxy-2-di-n-propylaminotetralin (8-OH-DPAT), a 5-HT1A agonist. These data are presented as a rare example of enantiomers which demonstrate opposite pharmacological effects at the same receptor.

In order to facilitate identification of possible metabolites arising from in vitro action of catechol-O-methyltransferase upon 7,8-dihydroxy- and 8,9-dihydroxy-4-n-propyl-1,2,3,4,4a,5,6,10b-octahydrobenzo[f]quinolines (11, 12), all four possible monomethyl ether derivatives have been synthesized. Incubation of 11 and 12 with the enzyme revealed that the 8,9-dihydroxy positional isomer 12 (which contains the dopamine moiety held in the beta conformation) but not the 7,8-dihydroxy isomer 11 (which holds the dopamine moiety in the alpha conformation) was a substrate for the enzyme. The sole detectable product of 12 was 8-hydroxy-9-methoxy derivative 15 in which the "meta" hydroxy group of the dopamine moiety is etherified.

Molecular modifications have been made on a highly potent, active antagonist to organophosphate-induced toxicity, 4,4'-bis[1,3-dioxan-2-ylmethyl)methylamino]acetyl]biphenyl dimethobromide (1). Stepwise removal of the oxygen atoms from the dioxane rings, as well as changing the position of attachment of substituents on the 1,3-dioxane rings and decreasing the ring size from six-membered to five-membered caused drastic or complete loss of pharmacological effect. Partial structures of 1 were all inactive. Thus, the structure of 1 seems to be remarkably specific. Additional pharmacological data are reported for 1.

Several reports have documented that renal cryoablation when used either via open or laparoscopic surgical techniques can be well tolerated in animal models. We sought to examine the feasibility of performing renal cryoablation percutaneously, under ultrasound guidance, in a porcine model. A total of 13 juvenile swine was treated. In each animal the lower pole of the left kidney was used as the target. Each animal had serum drawn for Hct, Wbc, CK, BUN, creatinine, and myoglobin pre- and postcryoablation and again at the time of sacrifice. Animals were sacrificed at 0–42 days postoperatively, and the treated renal units were harvested and submitted for histologic examination. The procedures were divided into three groups based on the extent of the freeze time. Group 1 (n= 4) was treated for 3–4 min, single freeze; Group 2 (n= 3), 6–7 min, single freeze; and Group 3 (n= 6), a double freeze-thaw cycle, each for 10 min. None of the animals in this experiment died or experienced significant clinical deteriorations at any time post-treatment. No significant differences in any of the measured serum markers were noted between pre- and post-treatment values. For animals in Groups 1 and 2 discrete cryolesions were created with sharp 1-mm borders and no perirenal reaction/damage to surrounding structures. For animals in Group 3 large areas of renal infarction/cryolesions were produced, with significant perirenal reaction in 5/6 animals and gross hydronephrosis/total renal loss in 2/6. Percutaneous renal cryoablation appears to be well tolerated in the porcine model which we used. Associated morbidity appears to be related to the extent of freezing, with a safety tolerance in the present study limited to target areas of approximately 3–5 cm3. These findings suggest that a pilot study of percutaneous renal cryoablation for patients with 3–4-cm exophytic lesions may be warranted.

A series of congeners of hemicholinium-3, in which the 1,4-oxazinium rings of hemicholinium are replaced by pyrrolidine, piperidine, 1,3-dioxane, or 1,4-oxazine rings, is described. Several of the target compounds produced blockade of neuromuscular transmission in the rabbit, and three heterocyclic derivatives, 10, 11, and 13, significantly antagonized paraoxon-induced lethality in mice. 1,3-Dioxane derivative 11 was an extremely potent antagonist of paraoxon-induced toxicity in mice, compared with prototypical protective agents physostigmine and pyridostigmine. Compound 11 exhibited a much more favorable therapeutic ratio than the reference drugs. The mechanism of action of 11 has not been elucidated, although it is concluded that it differs from that of hemicholinium-3 (inhibition of high-affinity, sodium-dependent uptake of choline into nerve terminals).

To measure serum CK-MB, a market of myocardial infarction (MI), in elderly men before and after cryoprostatectomy.Serum CK-MB was measured on each patient before and after cryoprostatectomy. Each patient's preoperative result was used as control measurement for comparison with measurements made after cryoprostatectomy.Inpatient operating room and postanesthetic recovery unit of a university-affiliated general hospital.38 male patients, mean (SEM) age 69.1 +/- 1.4 years, undergoing cryoprostatectomy.All patients had a 12-lead ECG prior to surgery, in the recovery room, and 24 hours after surgery. Serum CK-MB was measured prior to induction of anesthesia, on arrival in the recovery room, and at 8 and 24 hours after surgery. Lactate dehydrogenase (LDH) and isoenzymes also were measured in 10 patients before and after cryoprostatectomy.All patients underwent uneventful cryoprostatectomy. No patients had new ECG changes after surgery. All patients had normal serum CK and CK-MB concentrations before surgery. Serum CK and CK-MB were significantly elevated after cryoprostatectomy (p0.001). Enzyme values were greatest 8 hours after surgery: total CK mean 1453 +/- 145 U/L (range 199 to 3,356 U/L); CK-MB mean 52 +/- 3 ng/ml (range 12 to 114 ng/ml) or 5.0 +/- 0.5% of total CK (range 1.6% to 12.4%). All patients had significant elevations of LDH after cryoprostatectomy but did not show an increase in the ratio of LDH1 to LDH2 isoenzymes. Finally, unlike patients with an acute MI, the activity of CK-MB isoenzyme when measured by gel electrophoresis was two to three times greater (mean, 2.6 +/- 0.7) than the concentration measured with the monoclonal antibody assay in patients after cryoprostatectomy.Serum CK-MB is an unreliable test to diagnose an MI in patients who have undergone cryoprostatectomy.

The subject compounds were prepared as a part of a continuing structure-activity study of the contrasting actions (agonism-antagonism) of (+)- and (-)-11-hydroxy-10-methylaporphine at serotonin (5-HT1A) receptors. None of the targeted nonoxygenated aporphine derivatives demonstrated significant activity in assays for any effects at serotonin 5-HT1A receptors. It is concluded that, in the aporphine series, serotonergic agonist or antagonism requires an alkyl group ortho to a phenolic OH group in the A ring.

DOI (1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane) significantly depressed end plate current (EPC) amplitude. It decreased quantum content, increased the extent of neurally evoked EPC rundown during the train, produced a nonlinear current-voltage relationship, shortened time constant of decay, and depressed iontophoretically evoked EPC. The depressant response of DOI on EPC amplitude was antagonized by 5-HT1-like receptor antagonists, but was resistant to 5-HT2 and 5-HT3 receptor antagonists. This suggests that inhibitory 5-HT receptors roughly correspond to 5-HT1-like receptors.

The neuroblastoma-glioma hybrid cell (NG108-15) has a sodium-dependent, high-affinity choline transport system with a Km of 16.0 ± 3.4 μM and Vmax of 214.5 ± 27.7 pmol/min/mg protein. A-4, A-5 and HC-3 produce dose-dependent inhibition of high-affinity choline transport in NG108-15 cells. Following 24 h exposure to approximately the EC50 of each inhibitor, no significant decrease was found in total choline accumulation or in choline incorporation into phosphatidylcholine. However, when additional inhibitor was added during the 24 h incubation, significant decreases in choline accumulation were produced by A-4 and A-5. Following 24 h exposure to each compound, only A-4 was able to significantly affect free choline content. In contrast, each inhibitor was able to significantly decrease acetylcholine content following 24 h exposure. Possible reasons for consistent decreases in acetylcholine versus minimal changes in choline metabolism will be discussed.

On the basis of the premise that the dopaminergic agonist profile of 2-(di-n-propylamino)-5-hydroxy-6-methyltetralin (1a) is due to in vivo oxidation of the 6-methyl moiety and that 1a may represent a novel prodrug strategy, the vicinal methyl-hydroxyl substitution pattern was incorporated into the 6- and 7-positions of 2-(di-n-propylamino)tetralin to give the 6-methyl-7-hydroxy and 6-hydroxy-7-methyl isomers 8 and 9, respectively. A multistep synthetic approach was devised which permitted preparation of target molecules 8 and 9. Pharmacological data revealed that both target compounds exhibit modest dopamine-like effects in the cardioaccelerator nerve assay in the cat, but neither appeared to be metabolically activated as was the case with 1a. The effects of 9 (but not of 8) were antagonized by pretreatment with haloperidol. Thus, the 5-hydroxy-6-methyl substitution pattern in the 2-aminotetralins remains unique as a dopaminergic agonist prodrug structure.

A series of "nonclassical" nicotine antagonists was synthesized and compared to the "classical" nicotine antagonist, hexamethonium, by means of the isolated guinea pig atria preparation. 2 was found to be the most potent, followed by hexamethonium and the other antagonists. With the exception of 5, the bisquaternary compounds 1-3 and 7-9 were found to be more potent than the monoquaternary compounds 4, 6, and 10-12. Within a series of compounds (1-6 or 7-12), those compounds possessing two phenyl rings proved to be more potent than those possessing one or three phenyl rings. These and other aspects of the structure-activity relationship of this class of compounds are discussed.

RDS-127 (2-di-n-propylamino-4,7-dimethoxyindane) is a novel dopamine (DA) receptor agonist with potent central actions. RDS-127, apomorphine (APO), and bromocriptine (BRM) were compared for their ability to inhibit locomotor activity in rats following oral administration. APO, BRM, and RDS-127 produced time- and dose-dependent decreases in locomotor activity. While APO and BRM were equipotent in inhibiting locomotor activity, RDS-127 was 13.5 times more potent than either APO or BRM. A single oral dose of 32.0 μmol/kg of RDS-127 decreased locomotor activity greater than 50% for a period of 2 hr. The inhibitory effects of RDS-127 on locomotor activity were blocked by prior administration of sulpiride, suggesting the effects are mediated by DA receptors. While oral administration of APO or RDS-127 generally decreased locomotor activity, similar doses given subcutaneously increased locomotor activity. These data suggest that the route of administration can profoundly affect the biological actions of DA receptor agonists and the accompanying conclusions concerning the selectivity with which they interact with different receptor subtypes. The therapeutic application and design of orally effective DA autoreceptor agonists are discussed.

Series of N-alkylated derivatives of 2-amino-4,6-dihydroxyindan 3 and 6-amino-1,3-dihydroxybenzocycloheptene 2 were prepared for pharmacological testing as congeners of 2-amino-5,7-dihydroxytetralin, which elicits dopaminergic effects in a variety of assays. All of the subject compounds demonstrated a lower order of dopamine-like activity than the tetralin derivatives. Some of the subject compounds showed weak interactions with alpha 1- and beta 1-adrenoceptors, but the major determinant of activity seemed to be the nature of the N-alkyl substituent rather than ring size.

Modification of food intake and motor activity was investigated following administration of amphetamine (AMP), apomorphine (APO) and three novel 2-aminoindanes (2-AI): 2-di-n-propylaminoindane (JPC-60-36), 2-di-n-propylamino-5,6-dimethoxyindane (JPC-211) and 2-di-n-propylamine-4,7-dimethoxyindane (RDS-127). These compounds demonstrated dose- and time-related inhibition of food intake in male rats which were habituated to eating 4 hr each day. The ranked potencies were as follows: RDS-127 greater than AMP = APO greater than JPC-60-36 and JPC-211 was inactive. 2-di-n-Propylamine-4,7-dimethoxyindane (RDS-127) did not increase motor activity in a dose range that Significantly inhibited food intake (66% of control intake with 0.08 mumol/kg). Food intake inhibition was blocked by pimozide, but not by propranolol or phentolamine. The anorectic-like actions of RDS-127 were long-lasting (greater than 4 hr) and RDS-127 was approximately 3-fold more potent than amphetamine or apomorphine in producing increased locomotor activity; the other 2-aminoindanes were less potent in producing hyperactivity. Hyperactivity responses were blocked by pimozide, but not by alpha-methyl-p-tyrosine. These results suggest that 2-aminoindanes may modify motor behaviors, at least in part, via direct stimulation of dopamine receptors. The structure-activity relationships of 2-aminoindanes on locomotor activity and inhibition of food intake are discussed.

Series of N-alkylated derivatives of trans-octahydrobenzo[g]quinoline and of cis- and trans-octahydrobenzo[f]quinoline were prepared for pharmacological testing as congeners of 2-amino-5,7-dihydroxytetralin, which elicits dopaminergic effects in a variety of assays. Trans-fused compounds bearing N-ethyl or N-n-propyl displayed high potency/activity in inhibition of effect of stimulation of the cat cardioaccelerator nerve. Certain N-alkyl homologues in the octahydrobenzo[f]quinoline series showed high potency in binding studies in rat caudate homogenate.

Apomorphine induces a pecking response in pigeons and the effects of various drugs on this pecking response were studied. The pecking induced by apomorphine (1.64 μmole/kg) has a rapid onset, and lasts for approximately 1 hr. Pecking induced by apomorphine can be blocked by dopaminergic receptor-blocking agents such as chlorpromazine, haloperidol, bulbocapnine and morphine, but not by α- or β-adrenergic receptor-blocking agents. Cholinergic agents have an inhibitory effect on pecking. The inhibitory effect of oxotremorine can be reversed by the prior administration of atropine. Apomorphine can induce both pecking and emesis while apomorphine methiodide causes only emesis. This ivestigation indicates that the pecking induced by apomorphine is caused by the stimulation of central dopaminergic receptors and that central cholinergic systems have a modulating effect on pecking. Serotonergic systems might also inhibit the pecking induced by apomorphine.

Three series of bicyclic, semirigid congeners of beta-phenethylamine have been prepared for evaluation of the effect of ring size (and of concomitant conformational variation) on biological activity in a variety of assays for adrenergic and dopaminergic actions. Pharmacologic activity was associated with 2-aminotetralin and 2-aminoindan derivateves, but was not found with 6-aminobenzocycloheptene derivatives. Noteworthy is the ability of several aminotetralins and aminoindans to increase the hot-plate reaction time without eliciting dopaminergic effects. This action was not blocked by pretreatment with naloxone.

A synthetic precursor to a potent dopaminergic agonist, (RS)-4-hydroxy-2-(di-n-propylamino)indan, has been resolved by classical recrystallization procedures, and the absolute configurations of the enantiomers have been established by X-ray crystallographic analysis. The enantiomers were converted by literature procedures into (R)- and (S)-1. (R)-1 was approximately 100 times as potent as (S)-1 in an assay for dopamine agonist effect in the isolated cat atrium.

The so-called beta conformer of dopamine has been proposed to be involved in agonist--receptor interactions at several sites in the dopaminergic nervous system. Further to evaluate this proposal, rigid congeners of the beta conformer derived from linearly and angularly annelated octahydrobenzoquinolines have been synthesized. Certain N-alkylated trans-angularly annelated systems exhibited unusually potent and highly selective dopamine-like effects in an assay on a cardioaccelerator nerve preparation in the cat, but these compounds were inactive in a variety of assays for CNS effects. These compounds present a clear separation of CNS effects from some potent peripheral effects.

Summary Previous reports suggest that analogs of dopamine (DA) can produce hyperglycemia in rats by interacting with DA receptors. Experiments reported here indicate the site of action and describe the metabolic sequalae associated with the hyperglycemic effect of apomorphine (APO), produced in conscious unrestrained rats. Apomorphine was more potent when administered by intracerebroventricular (i.c.v.) injection than when given subcutaneously (s.c.). Very small doses of the DA receptor antagonist pimozide, given intraventricularly, blocked the hyperglycemic effect of apomorphine administered subcutaneously. Sectioning of the spinal cord at thoracic vertebra T1-2, or sectioning the greater splanchnic nerve blocked apomorphine-mduced hyperglycemia; whereas section of the superior colliculus or section at T5-6 had no effect. A dose of apomorphine or epinephrine (EPI) producing a similar degree of hyperglycemia elevated the concentration of EPI in serum to a similar degree, and the increase in EPI in serum preceded the increase in glucose in serum. Fasting animals for 2 or 18 hr had no significant effect on EPI- or apomorphine-induced hyperglycemia despite a reduction (91-93%) of the glycogen content of liver and skeletal muscle during the 18 hr fast. 5-Methoxyindole-2-carboxylic acid (MICA), an inhibitor of gluconeogenesis, blocked EPI- and apomorphine-induced hyperglycemia in rats fasted for 18 hr. However, 5-methoxyindole-2-carboxylic acid was ineffective in blocking hyperglycemia in animals fasted for 2 hr. Changes in insulin or glucagon in serum alone cannot account for the hyperglycemic action of apomorphine. These data demonstrate that apomorphine interacts with central DA receptors located in the hindbrain to activate sympathetic neuronal activity to the adrenal gland which subsequently releases epinephrine to alter homeostasis of glucose. Epinephrine may then, depending on the nutritional status, facilitate glycogenolytic or gluconeogenic processes to produce hyperglycemia.

Superfused helical strips of canine anterior mesenteric arteries and veins and canine dorsal metatarsal veins contract in response to prostaglandin B 2 (PGB 2 ). Reserpine pretreatment and phentolamine reduce the constrictor response to PGB 2 . PGB 2 enhances the contractile responses of these preparations to potassium, barium and norepinephrine. PGB 2 also produced a shift to the left in the duration of the barium response curve. The data presented demonstrate that PGB 2 is not an inactive metabolite of PGA 2 metabolism but possesses potent constrictor activity probably dependent on release of norepinephrine from adrenergic nerves. Furthermore, PGB 2 enhances the responses of vascular smooth muscle to vasoactive stimuli.

Three 5,8-dimethoxylated derivatives of 2-aminotetralin (2-AT) were compared with clonidine, methoxamine and phenylephrine in tests for sedation (inhibition of exploratory activity) and analgesia. In both tests the 2-AT derivatives were less potent than clonidine, but more potent than methoxamine or phenylephrine. Antagonism of the 2-AT derivative, DR-31, and clonidine by yohimbine in both tests argues for the involvement of α 2 -adrenoreceptors in the mediation of these behavioral effects. α 1 -Adrenoreceptors also mediate an inhibition of exploratory activity since the inhibition induced by methoxamine was antagonized by phenoxybenzamine (POB) but not by yohimbine. The methoxylated 2-AT derivatives, which have previously been shown to exert potent peripheral α 1 -agonism are now demonstrated to have sedative and anlgesic effectscharacteristic of central α 2 -adrenergic stimulation.

Phentolamine, which is considered a specific alpha-adrenoceptor antagonist, was tested for antagonist properties at presynaptic dopamine receptors and presynaptic alpha 2-adrenoceptors present on sympathetic nerve terminals in isolated right cat atria. Field stimulation induced a transient tachycardia which was inhibited by stimulation of presynaptic dopamine receptors using apomorphine or by stimulation of presynaptic alpha 2-adrenoceptors using clonidine. The presynaptic inhibitory effects of apomorphine were competitively antagonized by sulpiride, which is considered a specific dopamine receptor antagonist, and by phentolamine and yohimbine which are considered alpha-adrenoceptor antagonists. The presynaptic inhibitory effects of clonidine were competitively antagonized by phentolamine and yohimbine but not by sulpiride. pA2 values for phentolamine against apomorphine and phentolamine against clonidine suggest that phentolamine may be an antagonist at both presynaptic dopamine receptors and presynaptic alpha 2-adrenoceptors.

The interactions of 5,6- and 6,7-dihydroxy derivatives of 2-aminotetralin with [ 3 H]clonidine and [ 3 H]clonidine and [ 3 H]prazosin as well as with [ 3 H]spiperone binding sites in rat cerebral cortex membrane preparations were investigated. The hydroxy derivatives of 2-aminotetralin tested showed significant interaction with [ 3 H]clonidine as well as with [ 3 H]spiperone binding sites while for [ 3 H]prazosin binding site these agents appeared virtually inactive. For interaction with [ 3 H]clonidine binding site 6,7-dihydroxy substitutions impart greater potency that 5,6-dihydroxy substitutions and N-alkyl substitutions either make no difference or reduce the affinity of these compounds. N-alkyl substitutions, however, markedly enhance the affinity of 5,6-dihydroxy derivatives for interactions with [ 3 H]spiperone binding site. The results suggest that some hydroxy derivatives of aminotetralin have significant interaction with both central α 2 -adrenoceptor and D 2 -dopamine receptor systems.

The vinyl ethers of choline and of its alpha- and beta-methyl homologues were prepared to determine their cholinergic effects and to determine whether a separation of the dual physiologic activity (nicotinic and muscarinic) reported for the vinyl ether of choline could be achieved by this modification. A literature method of vinyl transetherification of amino alcohols has been studied and modified. The ethyl ethers of choline and of alpha- and beta-methylcholine were prepared for comparison with the vinyl ethers. Two independent, unequivocal syntheses of the ethyl ether of beta-methylcholine have been accomplished. This study showed that the two literature methods for synthesis of this compound are equivocal, and, hence, the biological data reported for this compound in the older literature may not be valid. Certain of the ethers showed marked nicotinic or muscarinic activities.

The title compounds have been synthesized and evaluated for emetic effects in the dog, actions on the cardioaccelerator nerve in the cat, pecking in pigeons, and for behavioral effects following both peripheral and direct intracerebral injection into the nucleus accumbens and caudate-putamen of the rat. Generally, in the series studied, the N,N-diethyl and N,N-di-n-propyl congeners of dopamine displayed notably high degrees of activity. However, the test compounds exerted differing effects on peripheral and central dopamine receptors and in the area postrema. Differentiations of the activities of the different homologues within the brain were also shown.

The cardiovascular effects of RDS−127 [2−di-n-propylamino−4,7−dimethoxyindane] were examined in normotensive, anaesthetized rats. RDS−127 given i.v. (12·5–125 μ kg−1) produced dose-dependent bradycardia. The bradycardic effect was 20·5 times more potent when the drug was administered intracerebroventricularly (i.c.v.) than when given i.v. RDS−127 produced a slight, but significant hypotension. Haloperidol given i.c.v. or i.v. reversed these bradycardic and hypotensive actions, whereas phentolamine was ineffective. Methylatropine partially reduced the bradycardic effect. These results suggest that RDS−127 activates central DA receptors to produce hypotension and bradycardia in rats.

Replacement of the catechol 3,4-dihydroxylation pattern of certain adrenergic beta-phenethylamines by a resorcinol 3,5-dihydroxylation pattern has led to a greater selectivity of adrenergic agonist effects in certain molecules. This strategy has been applied to a series of dopaminergic agents derived from 2-aminotetralin, leading to a 5,7-dihydroxylation pattern. Traditional literature approaches to formation of a tetralin ring with this oxygenation pattern failed. A method was used which involved cyclization of 3,5-dimethoxybenzylsuccinic acid derivatives with pyridinium poly(HF) and subsequent modification of the tetralin ring. The resorcinol-derived 2-aminotetralins were less potent and less active dopaminergic agents than their catechol-derived isomers (5,6-dihydroxy and/or 6,7-dihydroxy). Certain of the subject compounds demonstrated alpha- and beta 1-adrenoceptor activating properties.

d-Amphetamine was found to induce a pecking response in pigeons. The pecking response induced by d-amphetamine was antagonized by chlorpromazine, haloperidol or bulbocapnine indicating that this pecking response was caused by dopaminergic receptor stimulation. Pretreatment of pigeons with alpha-methyltyrosine (alpha-MT) reduced d-amphetamine-induced pecking, while the combined treatment of pigeons with alpha-MT and L-dihydroxyphenylalanine (L-DOPA, 100 mg/kg) partially restored the pecking response. d-Amphetamine-induced pecking was not reduced by a dopamine-beta-hydroxylase inhibitor, 1-phenyl-3-(2-thiazolyl)-2-thiourea (U-14,624). Alpha-MT reduced brain dopamine but not norepinephrine level, whereas U-14,624 decreased brain norepinephrine but not dopamine. Thus there is a correlation between brain dopamine level and d-amphetamine-induced pecking response. It is concluded that d-amphetamine-induced pecking is mediated indirectly by the release of dopamine.

Intraperitoneally administered R-(−)- and S-(+)- enantiomers of 2,5-dimethoxy-4-bromoamphetamine were evaluated for their ability to induce head-body shake, limb flick and abortive grooming behaviors in cats. The R-(−)-enantiomer was consistently more effective than the S-(+)-isomer in all three behavioral measures. Dose-response relationships were evident for head-body shakes and limb flicks for both enantiomers, but reliable abortive grooming responses appeared only after the higher doses of R-(−)-DOB. Cinanserin and methysergide pretreatments effectively antagonized the induction of head-body shakes and limb flicks by 0.1 mg/kg R-(−)-DOB. In addition, haloperidol pretreatment significantly antagonized the appearance of these behaviors suggesting that dopaminergic as well as serotonergic stimulation is involved in the elicitation of these cat behaviors by R-(−)-DOB.

A series of rigid analogs of apomorphine lacking aromatic hydroxyl substituents were evaluated for dopaminergic properties. Three compounds, N-methyl-N-propyl-2-aminotetralin (Me-Pr-2-AT), N, N-dipropyl-2-aminotetralin (Di-Pr-2-AT) and N, N-dipropyl-2-aminoindane (Di-Pr-2-AI) induced emesis in dogs, contralateral circling in unilaterally lesioned rats, and inhibited prolactin secretion. The induced circling responses, however, were attenuated by prior treatment with α-methyl-p-tyrosine methyl ester (AMPTME) and the compounds were weak inhibitors of 3H-dopamine binding in calf caudate homogenates. The posssiblity that these agents may be metabolically activated in vivo is discussed.

Two series of N-substituted 2-aminoindan systems have been prepared: 4,5-dihydroxy-2-aminoindan (1) has a hydroxylation pattern analogous to the alpha conformer of dopamine, and 5,6-dihydroxy-2-aminoindan (2) has a hydroxylation pattern of the beta conformer of dopamine. All members of both series demonstrated only extremely weak binding to calf caudate homogenate. Certain N-alkylated 4,5-dihydroxyindans were violent emetics in the dog and were potent in blockade of the effect of stimulation of the cardioaccelerator nerve of the cat. In contrast, the 5,6-dihydroxy series displayed low or no activity/potency in these assays. Conformational analysis of the 2-aminoindan system is described and discussed.

Aminotetralin derivatives M-8 and JOD-176, were studied in relation to isoproterenol for beta-adrenergic activity. M-8 and JOD-176 were found to be very weak in activating cardiac beta-receptors. These compounds were also found to be considerably more active in uterine and bronchial smooth muscle. Because these compounds were also shown to be very inactive in vascular smooth muscle, the possibility that beta-receptors in different smooth muscle types may also differ was suggested.

N-Alkylated derivatives of 2-amino-4,7-dimethoxyindan were prepared for evaluation of central and peripheral dopaminergic activity using biochemical and behavioral tests in the rat and cardiovascular responses in the cat. 2-(Di-n-propylamino)-4,7-dimethoxyindan (4e) demonstrated equal activity with apomorphine to activate peripheral presynaptic dopamine receptors. Central pre- and postsynaptic dopamine receptors were also activated with 4e. In contrast to the intense long-acting sympathomimetic actions previously reported for the 2-amino-5,8-dimethoxytetralins, these compounds produced weak, transient effects in heart rate and blood pressure. The majority of 2-amino-4,7-dimethoxyindan derivatives tested are weak or inactive pre- and postsynaptic dopamine receptor agonists.

Low doses of 5,6-dihydroxy-2-dimethylaminotetralin (M-7) produced inhibition of the linguomandibular reflex in the cat. This inhibition was similar to that produced by apomorphine and was blocked by haloperidol, bulbocapnine or chlorpromazine. M-7 also had a brief but marked hypertensive effect. Gradual bradycardia also developed. These results indicate that M-7 inhibits the linguomandibular reflex by interaction at dopamine receptors, or ‘apomorphine’ receptors.

In a continuing investigation of structural requirements for hemicholinium-like activity (inhibition of neuromuscular transmission due to inhibition of uptake of choline into nerve terminals), some additional molecular modifications of hemicholinium (“HC-3”; structure 1) were made. The target compounds were prepared by standard one- or two-step sequences. Noncyclic acetal moieties in general permitted retention of pharmacological activity, as did concomitant replacement of the central bi-phenyl “spacer” by other bulky cyclic groupings and replacement of the oxazinium rings by piperidine or 4-methylpiperidine. However, these modifications generally produced compounds of a lower potency. Replacement of the biphenyl moiety of HC-3 with polyalkylene chains permitted retention of a considerable degree of activity. In these target compounds, the two quaternary nitrogens can exist the same distance apart (approximately 14 A) as in the hemicholinium molecule. The ditertiary amino congener of a pharmacologically active bis-quaternary oxazinium compound was almost completely inactive. To date, only one tertiary amine has been found which displays a significant degree of hemicholinium-like activity.

The effect of droperidol on miniature endplate potential (mepp) frequency and amplitude, acetylcholine sensitivity, action potential generation, twitch tension, input resistance and alteration of acetylcholine release were studied in frog muscle. Interaction with d-tubocurarine was studied in the cat sciatic gastrocnemius preparation. Between 10 −11 and 10 −7 g/l droperidol did not change mepp frequency or amplitude. Between 7.5 × 10 −6 and 2.5 × 10 −5 g/l mepp amplitude, endplate sensitivity to acetylcholine and twitch tension were depressed. At 5 × 10 −5 g/l the threshold for action potential generation increased while amplitude and rate of rise decreased. Input resistance was unaltered. With indirect interrupted tetanic stimulation of the muscle for 30 min droperidol 10 −6 to 10 −4 g/l reduced the contraction height while acetylcholine release was concomitantly depressed. Droperidol 10 mg/kg in cats did not block muscle contraction, but combination with d-tubocurarine prolonged recovery time.

A series of cis- and trans-dihydroxycotahydrobenzo[f]quinoline congeners of dopamine has been prepared, in which the N substitutent is H, ethyl, or n-propyl. The trans isomers include the dopamine moiety held rigidly in an antiperiplanar diposition which is believed to be necessary for certian central and peripheral dopaminergic effects. The cis isomers are flexible molecules; the dopamine moiety lacks conformational integrity and it can exist in a conformation which is believed not to favor dopaminergic activity. The trans series of compounds was shown to possess a high level of central and peripheral dopaminergic effects, whereas the cis series was of low activity or was inert. These data further support previous proposals concerning stereochemical requirements for certain dopaminergic agonist activity.