In vitro effects of steroid hormones on arylalkylamine N-acetyltransferase (AA-NAT) activity in the pineal of fish, Clarias gariepinus (Burchell, 1822) during different phases of breeding cycle.
Indian J Exp Biol
;
2007 Aug; 45(8): 676-82
Artigo
em Inglês
| IMSEAR
| ID: sea-56708
ABSTRACT
In vitro effects of gonadal hormones (testosterone, 17beta-estradiol estriol and estrone) and corticosteroid hormones (corticosterone and cortisol) were studied on arylalklyamine N-acetyltransferase (AA-NAT) activity in the pineal organ of the fish, C. gariepinus during quiescent, progressive, breeding and regressive phases of its annual breeding cycle. The pineals were collected under dim red light, maintained in organ culture for 7 hr and incubated with three concentrations (10(-6), 10(-5) and 10(-4) M) of hormones for 6 hr. The treatments with gonadal hormones and corticosteroid hormones inhibited pineal AA-NAT activity in a dose-dependent manner during all the phases of the breeding cycle. AA-NAT activity was comparatively more sensitive to the inhibitory effects of the gonadal hormones during the regressive phase and less sensitive during the quiescent phase. Further, the enzyme activity was more sensitive to the inhibitory effects of corticosteroid hormones (corticosterone and cortisol) during the breeding phase and less sensitive during the quiescent phase. These findings seem to suggest that gonadal hormones and corticosteroid hormones have direct inhibitory influence on AA-NAT activity and, hence melatonin synthesis in the photoreceptive pineal organ of C. gariepinus.
Texto completo:
DisponíveL
Índice:
IMSEAR (Sudeste Asiático)
Assunto principal:
Glândula Pineal
/
Arilamina N-Acetiltransferase
/
Hormônios Esteroides Gonadais
/
Testosterona
/
Peixes-Gato
/
Cruzamento
/
Corticosteroides
/
Estradiol
/
Estriol
/
Animais
Idioma:
Inglês
Revista:
Indian J Exp Biol
Ano de publicação:
2007
Tipo de documento:
Artigo
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