235 Acute effects of endocannabinoid anandamide and CB1 receptor antagonist, AM251 in the regulation of thyrotropin secretion Marco Aure´lio Liberato Costa da Veiga1, Fla´via Fonseca Bloise1, Ricardo Henrique Costa-e-Sousa1, Luana Lopes Souza1, Norma Aparecida dos Santos Almeida1, Karen Jesus Oliveira1,2 and Carmen Cabanelas Pazos-Moura1, 1Laborato´rio de Endocrinologia Molecular, Instituto de Biofı´sica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil 2Departamento de Fisiologia e Farmacologia, Universidade Federal Fluminense, Rio de Janeiro 23070-200, Brazil (Correspondence should be addressed to C C Pazos-Moura; Email:
[email protected]) Abstract We examined the acute effects of endocannabinoid, ananda- hormones. Stimulatory effect of 0.17 mg/kg BW AM251 and mide, and of synthetic cannabinoid receptor antagonist, inhibitory effect of anandamide was abolished in the group AM251[N-(piperidin-1-yl)-1-(2,4-dichlorophenyl)-5-(4- injected with AM251 followed by an anandamide injection, chlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide], on 30 min later. Intracerebroventricular injection of 20 ng (but TSH, thyroxine (T4), and triiodothyronine (T3) secretions. not 200 ng) anandamide induced a decrease in serum TSH at Euthyroid male rats showed a 42% decrease in serum TSH, 2 h 60 min after injection, which tended to disappear at 120 min. after a single i.p. injection of 0.02, but not 0.2 mg/kg body Anterior pituitary explants presented significant reduction in K weight (BW), anandamide, accompanied by a 39% reduction TSH release in the presence of 10 7 M anandamide in . K in serum T4, without alteration in serum T3.At05 and 1 h, incubation medium, which was blocked by 10 7 M AM251.