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Objective: To evaluate the differences of oxidative stress level between obesity-prone rats and obesity-resistant rats., Methods: Male Wistar rats were divided into control group (10 rats) fed with basal diet and high fat group (30 rats) fed with high-fat diet for 6 weeks. Ten rats in obesity-prone (OP) group and obesity-resistant (OR) group were selected from the high-fat diet group according to the gain of body weight. All rats were killed by the end of 13th week. Serum SOD, MDA, GSH-Px, blood lipids and fatty acids were detected by standard methods., Results: SOD was lower in OP rats than that in OR rats and control rats. GSH-Px was lower in OP rats than that in OR rats. MDA was higher in OP rats than that in control rats. The energy intake, body fat content, FBG, serum lipids, serum insulin, ISI and free fatty acids in OP rats were significantly different from those in OR rats, but there were no differences between OR and control rats., Conclusion: Compared with OR rats, the oxidative stress responses were increased and the antioxidant capacities were decreased in OP rats after 13 weeks of experiment.

Objective: To measure the content of arginine vasopressin (AVP) and V1b receptor expression in the brain areas in rats of both genders and after rotatory stimulation and thereby, to identify the involvement of AVP in the mechanisms of motion sickness., Methods: SD rats were rotated about a horizontal axis for 30 min, the content of AVP and the expression of V1b receptors in some brain areas were then measured with radioimmunological analysis and immunofluorescent method respectively., Results: We proved that: (1) In female rats, the content of AVP in each area we measured in rotation group did not show any significant change compared with that in control group (P > 0.05). In male rats, the AVP content of control group in each area was higher than that of female rats, but reduced by rotatory stimulation in forebrain, diencephalon and pontine (P < 0.05 or 0.01), however, the changes in the cerebellum and medulla of rotation group were not significant (P > 0.05). (2) The positive cell number of V1b receptor expression in the supraoptic nucleus of female rats in rotation group was lower, but higher in the vestibular nucleus and area postrema than that in control group (P < 0.05 or 0.01). In male rats, the V1b receptor positive cell number in the supraoptic nucleus and vestibular nucleus of rotation group did not show significant change compared with that of control group (P > 0.05), but a slight increase in the medulla of rotation group rats was observed (P < 0.05)., Conclusion: The gender difference in the susceptibility of motion sickness is potentially associated with the discrepancies in AVP content in the forebrain, diencephalon and pontine, in the expression of AVP-V1 receptors in the vestibular nucleus and area postrema, and in responses to rotatory stimulation, and that the vestibular nucleus and area postrema may be the areas targeted by AVP V1 receptor antagonist for antimotion sickness.

Objective: To investigate the expression of dopamine D2 receptors (D2R) and dopamine transportors (DAT) located in the medial prefrontal contex (mPFC) in high and low conditioned place preference (CPP) rats, and to unveil the possible mechanism leading to different CPP susceptibilities., Methods: One hundred and sixty male Sprague-Dawley rats were randomly assigned into an experiment group (n = 130) and a control group (n = 30). The experiment group was re-classified into 2 groups according to CPP values:high preference group (HP group) and low preference group (LP group). According to the execution time-points after the last administration, the HP and LP group was classified into a 3-hour group (3 h), a 72-hour group (J3d), and a 14-day group (J14d), respectively. At 3 hours, 72 hours, and 14 days after the final injection, rats were killed and cardio-perfused, and the brains were removed and sliced up coronarily. The mRNA levels of D2R and DAT in mPFC were determined with in situ hybridization., Results: There were no significant differences of pretest scores staying at the non-preference chamber among the groups(P = 0.470). However, the test scores of the CPP time stayed at pretest natural preference in the HP group were significantly higher than those of the LP group(P = 0.000). In 3h, J3d, and J14d groups,the expressions of D2R mRNA in the HP group (125.43 +/- 2.90 approximately 142.92 +/- 3.32) were lower than those of LP group (122.25 +/- 2.20 approximately 136.67 +/-5.39) (P = 0.000). In 3h and J3d,the expressions of DAT mRNA in the HP group (157.00 +/- 3.55 approximately 145.15 +/- 3.69) were significantly lower than those of the LP group (150.69 +/- 3.12 approximately 138.84 +/- 3.99) (P = 0.000). In J14d, there were no differences among 3 groups in mPFC (P = 0.458)., Conclusion: D2R and DAT may be correlated closely and underlie the different susceptibilities to morphine induced CPP.

Objective: To investigate the modulatory effects of morphine on the susceptibility to pentylenetetrazole-induced seizures, and the involvement of endogenous histamine in this process., Methods: Both the wild-type (WT) mice and histidine decarboxylase (a key enzyme for histamine biosynthesis) deficient (HDC-KO) mice were subcutaneously injected with different doses of morphine, and 1 hour later the pentylenetetrazole solution (1.5 %) was infused into the tail vein at a constant rate of 0.3 ml/min. The minimal dose of pentylenetetrazole (mg/kg) needed to induce myoclonic jerks and clonus convulsion was recorded as the thresholds of seizures., Result: In WT mice, morphine dose-dependently decreased the thresholds of both myoclonic jerks and clonus convulsion. In HDC-KO mice, morphine at 10 mg/kg only significantly decreased the threshold of myoclonic jerks from (38.6 +/-2.9)mg/kg to (32.5 +/-0.7)mg/kg, but had no significant effect on the threshold of clonus convulsion [from (51.8 +/-2.1)mg/kg to (47.6 +/-1.2)mg/kg]. In addition, the value of decreased myoclonic jerks (15.8 +/-1.4)% and clonus convulsion (8.3 +/-0.9)% thresholds were much lower in HDC-KO mice than in WT mice [(26.1 +/-2.5)% and (20.8 +/-2.4)%, respectively]., Conclusion: Morphine can decrease the thresholds of pentylenetetrazole in induction of seizure, and the endogenous histamine may be involved in this process.