Brain somatostatin depletion by cysteamine attenuates the penile erection induced by serotonergic and dopaminergic, but not by cholinergic, activation in rats.
To clarify the role of brain somatostatin in the expression of penile erection, the effects of cysteamine, a somatostatin depletor, on the penile erection induced by serotonergic, cholinergic and dopaminergic stimulants were investigated in rats. Fenfluramine (0.1-10 mg/kg, i.p.), pilocarpine (0.032-3.2 mg/kg, i.p.) and apomorphine (0.01-1 mg/kg, i.p.) induced penile erection in rats, with bell-shaped dose-response curves. Pretreatment with cysteamine (200 mg/kg, s.c.) significantly attenuated the penile erection induced by fenfluramine and apomorphine, but scarcely affected that induced by pilocarpine. Neurochemical measures revealed that cysteamine pretreatment significantly reduced the somatostatin content in all brain regions examined. These results provide the first pharmacological evidence that the brain somatostatin may play an important role in drug-induced penile erection.
Matsuoka
N
N
Basic Research Group, Tsukuba Research Laboratories, Fujisawa Pharmaceutical Co. Ltd., Ibaraki, Japan.
Maeda
N
N
Yamazaki
M
M
Yamaguchi
I
I
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D003543:Cysteamine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D005277:Fenfluramine / Q000494:pharmacology; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D010410:Penile Erection / Q000187:drug effects*; D010862:Pilocarpine / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D018490:Serotonin Agents / Q000494:pharmacology*; D013004:Somatostatin / Q000378:metabolism*
D018491:Dopamine Agonists; D018721:Muscarinic Agonists; D018490:Serotonin Agents; D010862:Pilocarpine; D005277:Fenfluramine; D013004:Somatostatin; D003543:Cysteamine; D001058:Apomorphine