[Excitatory and inhibitory effects of nitric oxide on weight, size, and histological changes of rat cerebellum]

ABSTRACT

Nitric oxide [NO] is produced in different body organs in mammals and numerous physiological and pathological properties are attributed to this small molecule. The precursor of this substance in the body, L-arginine, is synthesized by the enzyme nitric oxide synthase [NOS], and it is catalyzed, and is inhibited by a substance called L-NG-nitroarginine methyl ester [L-NAME]. In this study we investigated the qualitative and quantitative effects of nitric oxide on cerebellar histopathology in vivo environment via increasing and decreasing its production. Forty Wister rats, weighing 200- 250 gr with a mean age of 8 weeks, were divided into 5 groups after making sure the rats were pregnant. Except the control group, the other pregnant groups, respectively received 2 ml/kg normal saline, 200 mg/kg L-arginine, 20 mg/kg L-NAME and a mixture of the same doses of L-arginine and L-NAME on the third, fourth and fifth days of pregnancy. On day 18 of pregnancy, we anesthetized the rats, excised the cerebellum after craniotomy and fixed the organs in 10% formalin. We later prepared 5 to 6-micron in thickness tissue sections and dyed them by the routine Hematoxylin and eosin [HE] and Masson's Trichrom staining methods before studying them by light microscopy. There was a significant difference between the rats receiving L-arginine and the rats in other groups [P<0.01]. This study showed that L-NAME is capable of significantly decreasing the injury caused by nitric oxides in rat cerebellum