The changes of the thyroid function and serum testosterone levels after long-term L-NAME treatment in male rats.
Nitric oxide is a highly reactive gas that is produced by many tissues and exerts a series of physiological and pathophysiological effects. We studied the changes of the serum testosterone, thyroxine and thyrotropin levels, thyroid and anterior pituitary weights and thyroid cGMP concentrations in male Wistar strain rats treated with estradiol benzoate (EB) (1 mg/kg, im twice a week) and nonselective NO-synthase inhibitor L-NAME (N-omega-nitro-L-arginine methyl ester) alone and with combination of these substances. We have found that L-NAME in a dose 100 mg/kg/day but not in a dose 50 mg/kg/day increased the serum thyroxine and testosterone levels and in the case of testosterone in a higher dose partially blocked its drop when administered simultaneously with EB. The serum thyrotropin levels significantly fell after L-NAME and EB treatment. The cGMP thyroid levels changed only slightly in groups treated EB and L-NAME alone and were significantly decreased in group treated with combination of these substances. The nitric oxide thus seems to be an important modulator of thyroid and testicular function. The cGMP activation cascade is not probably involved in the nitric oxide induced changes of thyroid function.
Haluzík
M
M
III Department of Internal Medicine, 1 Faculty of Medicine, Charles University, Prague, Czech Republic.
Nedvídková
J
J
Kopský
V
V
Jahodová
J
J
Horejsí
B
B
Schreiber
V
V
D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013739:Testosterone / Q000097:blood*; D013961:Thyroid Gland / Q000187:drug effects* / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood
D004791:Enzyme Inhibitors; D013739:Testosterone; D004958:Estradiol; D013972:Thyrotropin; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP; D013974:Thyroxine; D019331:NG-Nitroarginine Methyl Ester