[ effect of beforehand and simultaneous oral contraceptive administration on urine total and free morphine concentration in tolerance and dependency models of rat]

Background: Addiction to opioid drugs is considered as a problem throughout the world. Addiction can be studied concerning: social, medical and psychological aspects. The social aspect of addiction is quite important. For example, the negative result of addiction test is a requirement for marriage and job by law. On the other hand, frauds in addiction tests have been reported [such as displacement of urine from bladder, alkalization or acidification of urine and taking of diuretics or oral contraceptives]

Materials and Methods: In the present study, two different chronic morphine administration protocols [tolerance and dependency models] were applied. Estrogen and progesterone were given prior and simultaneously with morphine. After the last injection of morphine, urine samples were taken every 6 h for 24 h. Then morphine was quantitatively detected by High Performance Liquid Chromatography [HPLC]. Data analysis was performed using two-way ANOVA and repeated measures ANOVA test followed by Student-Newman-Keuls test. Conjugated morphine was measured by the subtraction of free part of morphine from the total one in the urine samples

Results: Our results indicated that prior administration of estrogen and progesterone increased the metabolism of morphine 6 and 12 h after the last injection, while no significant change was detected after 18 and 24 h

Conclusion: In summary, it can be concluded that estrogen and progesterone transiently affect the metabolism of morphine. Thus, the effect of the sex hormones on morphine metabolism is not clinically important

Role of nitric oxide in stress-induced gastric damage in cholestatic rats

In this study the effect of nitric oxide synthesis inhibition on stress-induced gastric damage was evaluated in bile.duct ligated sham operated and unoperated rats. Animals were injected intraperitoneally with N g nitro-L-arginine methylester [L-NAME] 40 mgl/kg, L-arginine, 200 mg/kg or saline, 30 min before water-immersion stress. One hour after water immersion, the animals were killed and tneir stomachs were removed for measurement of gastric mucosal damage The results showed that L-NAME significantly enhances the development of gastric mucosal lesion in sharm operated and unoperated rats, while in bile duct ligated animals L-NAME decreases and L-arginine enhances the potentiation of stress-induced gastric mucosal damage. The results suggest that inhibition of nitric oxide synthase with L-NAME has different effects on stress-induced gastric damage in cholestatic rats compared with normal animals