Tehran University Medical Journal

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One of the useful function of melatonin is its protective effect against endogenous oxidants. The object of this investigation was to study the protective effect of melatonin on stress-induced gastric lesions.
Results: Our results show that pretreatment of animals with melatonin decrease the stress-induced gastric lesions dose dependently.
L-NAME, a nitric oxide synthesis inhibitor, potentiat the stress-induce gastric lesions and melatonin produced gastro-protective effect against concurrent stress and L-NAME-induced gastric lesions.
Conclusion: Our results indicate that melatonin may produce its gastro-protective effect Via increasing level of nitric oxide.

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Obstructive cholestasis is associated with overproduction of endogenous opioids (EOP), nitric oxide (NO), and cytokins in the blood streams. Therefore we investigated the relationship between obstructive cholestasis and function of germ cells in adult male rats.
Material and Methods: To study this, we used three groups of animals: No-surgery, Sham-surgery, and surgical ligation of the bile duct. After 3 weeks all animal were killed by ether, serum concentrations of FSH, LH and testosterone were determined by Radioimmunoassay, apoptosis was evaluated by DNA fragmentation detected by in situ terminal deoxynucloetidyl Transfrase-mediated dUTP nike end labeling (TUNEL).
Results: The mean of FSH level in cholestatic, control and sham groups were 13.22+ 1.038, 18.14+ 1.276, and 16.92+ 1.072 ng/ml, respectively. The mean of LH level in cholestatic, control and sham groups were 0.83 + 0.21, 2.058 ± 0.26, and 1.84 + 0.17 ng/ml, respectively. In addition, the mean of testosterone level in cholestatic, control and sham groups were 1.52 ± 0.16, 2.41 ± 0.18, and 2.31 + 0.14 ng/ml, respectively. The results of this study were indicated that serum FSH, LH and testosterone were significantly lower in cholestatic than control and sham groups (p=0.0195, P= 0.0029, and P=0.0023, respectively). However there was no significant difference in apoptotic index between all of groups (P=0.195). The apoptotic index in cholestatic, control and sham rats were 9.897± 1.374, 7.086 + 0.91, and 7.729 + 1.101, respectively.
Conclusion: These findings have been shown which as obstructive cholestasis was decreased the levels of serum gonadotropins and testosterone but it has no significant effector testicular germinal cells apoptosis.

 

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Background: Relaxation of the corpus cavernosum plays a major role in penile erection. Nitric oxide (NO) is known to be the most important factor mediating relaxation of corpus cavernosum, which is mainly derived from nonadrenergic noncholinergic (NANC) nerves. The aim of the present study was to investigate the effect of biliary cirrhosis on nonadrenergic noncholinergic (NANC)-mediated relaxation of rat corpus cavernosum as well as the possible relevant roles of endocannabinoid and nitric oxide systems.

Methods: Corporal strips from sham-operated and biliary cirrhotic rats were mounted under tension in a standard oxygenated organ bath with guanethidine sulfate (5 µM) and atropine (1 µM) to induce adrenergic and cholinergic blockade. The strips were precontracted with phenylephrine hydrochloride (7.5 µM) and electrical field stimulation was applied at different frequencies (2, 5, 10, 15 Hz) to obtain NANC-mediated relaxation. In separate precontracted strips of the sham and cirrhotic groups, the concentration-dependent relaxant responses to sodium nitroprusside (10 nM-1mM), as an NO donor, were assessed.  

Results: The NANC-mediated relaxation was significantly enhanced in cirrhotic animals (P<0.01). Anandamide potentiated the relaxations in both groups (P<0.05). The cannabinoid CB1 receptor antagonist AM251 (10 µM) and the vanilloid receptor antagonist capsazepine (10 µM) each significantly prevented the enhanced relaxations in cirrhotic rats (P<0.01). The CB2 receptor antagonist AM630 had no effect on relaxations in the cirrhotic group. In a concentration-dependent manner, L-NAME (30-1000 nM) inhibited relaxations in both the sham and cirrhotic groups, although cirrhotic groups were more resistant to the inhibitory effects of L-NAME. The degree of relaxation induced by sodium nitroprusside (10 nM-1 mM) was similar in the two groups.

Conclusions: Biliary cirrhosis enhances the neurogenic relaxation in rat corpus cavernosum probably via the NO pathway and cannabinoid CB1 and vanilloid VR1 receptors.