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  • Title: [Effect of androgens (testosterone, 5 alpha-dihydrotestosterone, 3 alpha, 17-beta androstanediol and 3 beta, 17 beta androstenediol) on the nocturnal activity of N-acetylserotonin methyltransferase and hydroxyindole O-methyltransferase in the pineal body of castrated rats].
    Author: Pavlikov SA, Isachenkov VA.
    Journal: Probl Endokrinol (Mosk); 1979; 25(5):72-7. PubMed ID: 573896.
    Abstract:
    To prove the effect of sex steroid hormones on the specificity of the pineal organ metabolism the activity of melatonin-synthesizing enzymes--N-acetylserotonine transferase (AST) and hydroxyindol-O-methyltransferase (HIMT) in the circadian rhythm was studied in castrated animals and in those administered androgens (testosterone 5 alpha-dihydrotestosterone, 3 alpha, 17 beta-androstandiol). Male Wistar rats, aged 30 days, kept for 12 hours under light conditions and for 12 hours in darkness were used in these experiments. Androgens (50 micrograms) were injected to rats two days after castration and 1 to 6 hours before the animals were sacrificed (at 2 a.m.). Activity of the enzymes under study was maximal at night (between 2 and 3 a.m.). Castration of rats weakened the peaks of the AST and HIMT activities by 30 and 40%, respectively. A single androgen administration stimulated the nocturnal rise of both androgens activities in 2 to 4 hours. By physiological activity the androgens were distributed in the following way: 5 alpha-dihydrotestosterone, 3 alpha, 17 beta-androstandiol, testosterone. beta-Epimer of androstandiol produced no effect on AST and HIMT activities in the epiphyses of castrated rats. Experimental data demonstrate that epiphysis serves as the target organ for sex steroid hormones, and that androgens are capable of modulating the melatonin-synthesizing enzymes' activity.
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