Effect of altered thyroid and adrenal activity on the seasonal reproduction of the Indian palm squirrel, Funambulus pennanti

Abstract

SINGH, A.B., and CHATURVEDI, C.M. 1993. Effect of altered thyroid and adrenal activity on the seasonal reproduction of the Indian palm squirrel, Funambulus pennanti. Can. J. Zool. 71 : 1558 -156 1. Thiouracil and metyrapone administered during the progression phase of the annual reproductive cycle inhibited gonadal development in the Indian palm squirrel, Funambulus pennanti. In a further experiment, these drugs led to normal gonadal regression during the late breeding phase. Thyroxine and corticosterone treatment, on the other hand, maintained the gonads continuously in breeding condition, unlike those of controls, which exhibited characteristic post-reproductive regression. Since hypofunction of the thyroid and adrenal glands had inhibitory effects on the initiation of seasonal gonadal growth, and hyperactivity affects post-reproductive regression, it is suggested that an optimal level of hormones is required for the normal breeding cycle in this subtropical mammal. The results are discussed in terms of an interrelationship between the seasonal thyroid, adrenal, and gonad cycles under natural conditions. SINGH, A.B., et CHATURVEDI, C.M. 1993. Effect of altered thyroid and adrenal activity on the seasonal reproduction of the Indian palm squirrel, Funambulus pennanti. Can. J. Zool. 71 : 1558-1561. Au cours d'une experience, l'administration de thiouracil et de metyrapone au cours de la phase de progression du cycle annuel de reproduction a eu pour effet d'inhiber le developpement des gonades chez 1'Ecureuil des palmes, Funambulus pennanti. Au cours d'une autre experience, l'administration de ces drogues durant la dernikre phase de la reproduction a donne lieu a une regression normale des gonades. En revanche, un traitement a la thyroxine et a la corticostCrone a assure le maintien de 1'Ctat reproducteur de la gonade, alors que les gonades des Ccureuils temoins ont subi la regression post-reproductrice caractkristique. Comme un hypofonctionnement de la thyro'ide et des surrenales a des effets inhibiteurs sur le declenchement de la croissance gonadique saisonnikre et puisque l'hyperactivite affecte la regression des gonades, on peut supposer qu'il existe une concentration optimale des hormones pour que le cycle de la reproduction soit normal chez ce mannifkre subtropical. Les resultats sont examines a la lumikre des relations qui prevalent entre les cycles saisonniers de la thyro'ide, des surrenales et des gonades dans des conditions naturelles.[Traduit par la ridaction]

Interaction of specific temporal phase relations of circadian neural oscillations and long term photoperiodic responses in Japanese quail, Coturnix coturnix japonica

“…Further, 12-h temporal phase relations of neural oscillations alter the photo sexual responses of immature Japanese quail while the 8-h relation of serotonergic and dopaminergic drugs induce reproductive regression in quail under relatively short-day lengths (<11 h) and exhibit scotosensitive responses under short days (Bhatt and Chaturvedi, 1992a). Specific phase relations of neural oscillations are also reported to modulate reproduction in mammals whether seasonal (Syrian hamster- Wilson and Meier, 1989;Indian Palm Squirrel-(Chaturvedi and Jaiwal, 1990;Jaiwal and Chaturvedi, 1991;Chaturvedi and Singh, 1992;Singh and Chaturvedi, 1993) or continuous breeders (laboratory mice- Sethi and Chaturvedi, 2009;Sethi et al, 2010). Thus, both photoperiod and specific temporal phase relations of neural oscillations appear to be regulators of gonadal development/activity in many avian and mammalian species.…”