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Effect of temperature on the seasonal production of androgens, in vitro , by the lizard tiliqua rugosa
THE EFFECT OF CHLOROQUINE PHOSPHATE ON THE INTERACTION OF ESTRADIOL WITH THE RAT UTERUS Dada, O.A., Martins, 0.0. Chemical Pathology Dept. University of Ibadan, Ibadan, Nigeria The mechanism of the antifertility effect of the antimalarial drug chloroquine phosphate (CQ) is not known. Although CQ inhibits LHinduced steroidogenesis in rat ovarian cells in vitro, no significant effect of the drug has been observed followingtheinistration of a single dose of CQ in vivo to adult rats. In the present studx monged treatment of rats with CQ (12mg/ kglgfor 8 days was found to enhance markedly the uterine uptake of H-estradiol in ovariectomised adult albino rats compared to saline treated controls. However, this effect was not accompanied by any significant change in the-uterine concentration of cytoplasmic estradiol receptor binding sites or in the dissociation constant of the estradiol receptor.
.._ EFFECT OF TESTOSTERONE ENANTHATE ADMINISTRATION ON MOUSE GERMINAL CELLS AND BLOOD ANDROGEN LEVELS; Bansal,*M.R( Davies, A.G. Department of Physiology,The Medical School, University of Birmingham, U.K. *Present Address: Department of Biophysics, Panjab University, Chandigarh 160 014, INDIA Testosterone in relatively small doses inhibit secretion of gonadotrophins and thus suppress spermatogenesis. This low dose of testosterone is adequate to maintain the accessory sex glands and libido but are insufficient to maintain spermatogenesis, because of anatomical location of the seminiferous tubules close to the source of endogenous testosterone in Leydig cells. In the present investigations low doses of testosterone enanthate (TE) were used to investigate the feasibility of this steroid as an antifertility agent. Adult male LACA mice were administered TE at a dose of 0, 40, 80, or 160 pg three times a week S.C. in sesame oil for 4, 8, or 12 weeks. Treatment of TE 80 or 160 ug for 8 or 12 weeks reduced testis weight and increased seminal vesicle weight. RIA indicated that treatment increased serum testosterone level. TE decreased the number of step 16 and step 7 spennatids, pachytene spennatocytes and type A spennatogonia. TE also reduced the proportion of step 7 spennatids which matured to form step 16 spenaatids. Dose-response to TE in mouse is different as compared to other experimental animals and humans. _ 113 BPPECT OF TEMPERATUREON THE SEASOnALPRODUCTION OF AND?iOGENS,IN VITRO, BY THE LIZARD TILIQUA RUGOSA; Bourne, A.R.; Watson, T.G.; Biological Sciences, Ueakin University; Victoria, 3217; AUSTRALIA Temperature appears to be the most important environmental cue controlling reproduction ir reptiles(l). The present study examines the effects of various incubation temperatures on the seasonal production of androgens, in vitro, by the scincid lizard Tiligua (Trachydosaurus) rugosa. This Australian lizard is unusual in that the testis produces epitestosterone (in addition to testosterone) as a major Cl9 steroid(Z). Testicular tissue was incubated, in vitro, at various temperatures (18, 25, 32, and 370C). These are within the normal body temperature range for T. rugosa. The production of endogenour androgens (testosteroneand epitestoeterone) was measured by radioiaununoassay. Epitestosterone production was maximal at 37OC and minimal at 18OC. There was no consistent effect of incubation temperature on testosterone production. The seasonal pattern of androgen production was not altered by changes in incubation temperature. The results suggest that temperature may play a part in the seasonal regulation of androgen production in T. rugosa, by inducing changes in the activity of the enzyme (presumably 17c-oxidoreductase) directly involved in synthesising epitestosterone. (1) Licht, P. (1972) Gen. Comp. Endocrinol. Suppl. 3, 477-488. (2) Bourne, A.R.; Taylor, J.L.; Watson T.G. (1985) Can. Camp. Bndocrinol. 58, 394-401.
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.._ EFFECT OF TESTOSTERONE ENANTHATE ADMINISTRATION ON MOUSE GERMINAL CELLS AND BLOOD ANDROGEN LEVELS; Bansal,*M.R( Davies, A.G. Department of Physiology,The Medical School, University of Birmingham, U.K. *Present Address: Department of Biophysics, Panjab University, Chandigarh 160 014, INDIA Testosterone in relatively small doses inhibit secretion of gonadotrophins and thus suppress spermatogenesis. This low dose of testosterone is adequate to maintain the accessory sex glands and libido but are insufficient to maintain spermatogenesis, because of anatomical location of the seminiferous tubules close to the source of endogenous testosterone in Leydig cells. In the present investigations low doses of testosterone enanthate (TE) were used to investigate the feasibility of this steroid as an antifertility agent. Adult male LACA mice were administered TE at a dose of 0, 40, 80, or 160 pg three times a week S.C. in sesame oil for 4, 8, or 12 weeks. Treatment of TE 80 or 160 ug for 8 or 12 weeks reduced testis weight and increased seminal vesicle weight. RIA indicated that treatment increased serum testosterone level. TE decreased the number of step 16 and step 7 spennatids, pachytene spennatocytes and type A spennatogonia. TE also reduced the proportion of step 7 spennatids which matured to form step 16 spenaatids. Dose-response to TE in mouse is different as compared to other experimental animals and humans. _ 113 BPPECT OF TEMPERATUREON THE SEASOnALPRODUCTION OF AND?iOGENS,IN VITRO, BY THE LIZARD TILIQUA RUGOSA; Bourne, A.R.; Watson, T.G.; Biological Sciences, Ueakin University; Victoria, 3217; AUSTRALIA Temperature appears to be the most important environmental cue controlling reproduction ir reptiles(l). The present study examines the effects of various incubation temperatures on the seasonal production of androgens, in vitro, by the scincid lizard Tiligua (Trachydosaurus) rugosa. This Australian lizard is unusual in that the testis produces epitestosterone (in addition to testosterone) as a major Cl9 steroid(Z). Testicular tissue was incubated, in vitro, at various temperatures (18, 25, 32, and 370C). These are within the normal body temperature range for T. rugosa. The production of endogenour androgens (testosteroneand epitestoeterone) was measured by radioiaununoassay. Epitestosterone production was maximal at 37OC and minimal at 18OC. There was no consistent effect of incubation temperature on testosterone production. The seasonal pattern of androgen production was not altered by changes in incubation temperature. The results suggest that temperature may play a part in the seasonal regulation of androgen production in T. rugosa, by inducing changes in the activity of the enzyme (presumably 17c-oxidoreductase) directly involved in synthesising epitestosterone. (1) Licht, P. (1972) Gen. Comp. Endocrinol. Suppl. 3, 477-488. (2) Bourne, A.R.; Taylor, J.L.; Watson T.G. (1985) Can. Camp. Bndocrinol. 58, 394-401.
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