Stress inhibits seasonal and FSH‐induced ovarian recrudescence in the lizard,Mabuya carinata

Abstract

Stressors (handling, chasing, and noise) applied randomly five times per day for one month to lizards during the recrudescence phase of the ovarian cycle caused a significant reduction in mean number of oocytes and primordial follicles when compared to those of controls. Further, vitellogenic follicles were absent in the ovary of lizards subjected to stressors. Administration of bovine FSH during post-breeding regression phase of the ovarian cycle induced ovarian recrudescence as shown by significant increases in the mean number of oogonia, oocytes, and primordial follicles compared to controls, as well as vitellogenic growth of follicles. However, lizards treated with FSH and exposed to stressors did not exhibit ovarian recrudescence. Furthermore, FSH administration during the post-breeding regression phase caused a significant increase in serum levels of estradiol compared to controls, which was accompanied by significant increases in the relative weight of the liver and oviduct, as well as vitellogenic growth of follicles. Despite administration of FSH to lizards subjected to stressors, there was neither any increase in serum levels of estradiol and weight of the liver nor vitellogenic growth of follicles. The results indicate that repeated application of stressors inhibits vitellogenic growth of follicles by suppression of steroidogenic activity in M. carinata. This is the first report revealing that the ovary does not respond to gonadotrophin treatment under stressful conditions in reptiles.

Influence of stress on gonadotrophin induced testicular recrudescence in the lizardMabuya Carinata

“…Chronic low humidity or overcrowding inhibits vitellogenic growth of ovarian follicles in the lizard A. carolinensis maintained under stimulatory photothermal conditions (Summers '88;Summers et al,'95). A similar inhibition of vitellogenic follicular growth is observed in the lizard M. carinata following stress due to handling, chasing, and noise (Ganesh and Yajurvedi, 2002a). The present study, wherein lizards were exposed to mild acute stressors over a period of one month during the recrudescent phase of the reproductive cycle, reveals that stress also interferes with spermatogenesis and spermiogenesis in reptiles.…”

“…alligators (Lance and Elsey, '86), and lizards (Dauphin-Villemant and Xavier, '87; Cree et al, '90) in captivity, and capturing (Moore et al,'91) and handling (Ganesh and Yajurvedi, 2002a) of lizards reduces serum levels of sex steroids. Similarly, the inhibitory effect of stress on gametogenesis has been reported in two species of reptiles, A. carolinensis and M. carinata.…”

“…It is interesting to note that in female M. carinata germinal bed activity as well as follicular development in the ovary did not respond to FSH treatment in lizards exposed to stressors (Ganesh and Yajurvedi, 2002a), whereas in males FSH could induce spermatogonial proliferation. Spermatocytes, spermatids, and spermiogenesis did not respond to FSH under stressful conditions.…”

“…Although, several studies report reduced sex steroid secretion due to stress in reptiles (review,Guillette et al,'95), impact of alteration in sex steroid secretion on gametogenesis has not been thoroughly investigated. Thus far, effects of stress on gametogenesis have been studied in only two species of reptiles, Anolis carolinensis (Summers,'88;Summers et al,'95) and Mabuya carinata (Ganesh and Yajurvedi, 2002a), in which stress interferes with vitellogenic growth of ovarian follicles. Stress induced alteration, if any, in spermatogenesis, has not been studied.…”

Ultrasound examination and behavior scoring of captive broadnose sevengill sharks, Notorynchus cepedianus (Peron, 1807)

“…Bella sustained a muscular injury after a weighing attempt before the study period, and it is possible that this affected her reproductive cycle. The adverse effects of stress on the reproductive cycle of nonmammalian vertebrates have been well established [Contreras-Sanchez et al, 1998;Pankhurst and Van Der Kraak, 2000;Ganesh and Yajurvedi, 2002]. Importantly, the process of vitellogenesis can be affected by stress in the rainbow trout (Oncorhynchus mykiss) [ContrerasSanchez et al, 1998] and the lizard Mabuya carinata [Ganesh and Yajurvedi, 2002].…”