Journal ArticleDOI
Effect of Pinealectomy on Testosterone, Estradiol-17?, Esterone, and 17?- Hydroxyprogesterone Levels During the Annual Reproductive Cycle in the Freshwater Catfish, Clarias batrachus
P.K. Nayak,T. P. Singh +1 more
TLDR
In this species the pineal gland during the annual reproductive cycle appears to have either inhibitory, stimulatory, or no effect on gonadal physiology depending upon the sexual conditions.Abstract:
The present study examines the relationship of the pincal gland to gonadal activity during the annual reproductive cycle in the freshwater catfish Clarias batracbus. The hormonal profiles of testosterone, estradiol-17β, estrone, and 17α-hydroxyprogesterone along with the gonadosomatic index (GSI) were monitored to assess the effect of pinealectomy. Pinealectomy appeared to accelerate the gonadal development from January to May. Removal of pineal prior to the start of gonadal recrudescence (January and February), induced initiation of ovarian recrudescence earlier than scheduled in nature. On the other hand pinealectomy during the vitellogenic phase (May to June) reduced the gonadal activity, suggesting the stimulatory role of pineal on gonads. During the remaining period of July to December (postvitellogenic and early resting phase) pinealectomy had no effect on gonadal activity. Thus, in this species the pineal gland during the annual reproductive cycle appears to have either inhibitory, stimulatory, or no effect on gonadal physiology depending upon the sexual conditions.read more
Citations
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Journal ArticleDOI
The pineal organ of teleost fishes
Peter Ekstrzm,Hilmar Meissl +1 more
TL;DR: There are strong indications that the pineal organ is one component in a central neural system that constitutes the photoperiod-responding system of the animal, i.e. the system that is responsible for correct timing of daily and seasonal physiological rhythms.
Journal ArticleDOI
Melatonin in non-mammalian vertebrates: Physiological role in reproduction?
TL;DR: The data available to date do not support the concept that melatonin plays an important physiological role in the photoperiodic control of reproduction in non-mammalians.
Journal ArticleDOI
Effects of melatonin on the behavioral and hormonal responses of red-sided garter snakes (Thamnophis sirtalis parietalis) to exogenous corticosterone.
TL;DR: The hypothesis that melatonin may function as a serotonin receptor antagonist is proposed, supporting a direct effect of melatonin and corticosterone on courtship behavior that is independent of any effect on androgen concentrations.
Journal Article
Seasonal effects of melatonin on ovary and plasma gonadotropin and vitellogenin levels in intact and pinealectomized catfish, Clarias batrachus (Linn).
Juthika Ghosh,Panchanan Nath +1 more
TL;DR: Melatonin showed variable effects (inhibitory and/or no effect) to GSI, mean number of yolky oocytes and plasma Vg levels but a consistent inhibiton of plasma GtH II levels indicating that melatonin may control the reproduction by blocking the GTH II release from the pituitary via affecting the hypothalamo-hypophysial axis.
References
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Journal ArticleDOI
The pineal organ: photoperiod and reproductive cycles in the goldfish, Carassius auratus L.
Journal ArticleDOI
Effects of pinealectomy, blinding, and sexual condition on serum gonadotropin levels in the goldfish.
Alice Hontela,R.E. Peter +1 more
TL;DR: The results indicate that the pineal influences gonadal development through, at least in part, alteration of the daily cycles of serum GTH levels in goldfish.
Journal ArticleDOI
Effects of pinealectomy on gonadal activity in the cyprinid teleost, Notemigonus crysoleucas☆
TL;DR: The data suggest that the pineal in Notemigonus may be either stimulatory or inhibitory to gonadal development depending on the photoperiod-temperature regime to which the fish are exposed.
Journal ArticleDOI
Seasonal Effects of Pinealectomy on Gonadal Activity in the Goldfish, Carassius auratus
Journal ArticleDOI
Effects of restricted photoperiod and melatonin administration on gonadal weight in the japanese killifish
TL;DR: The mode of action of the pineal in inhibiting gonadal development in the fish is studied to study the mechanism behind the reduced light period in Oryzias latipes and it is postulated that the Pineal gland plays some role in the mechanism.
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Effects of pinealectomy, blinding, and sexual condition on serum gonadotropin levels in the goldfish.
Alice Hontela,R.E. Peter +1 more