Journal of Endocrinology and Reproduction

S. W. Santosh ¹, S. Dijju ¹, R. M. Inbaraj ¹

Affiliations
1 Department of Zoology, Madras Christian College, Tambaram, Chennai-600 059, IN

Abstract

Indian major carp are important edible fishes in India. By studying the levels of sex steroids present in different regions of the brain will help us to manipulate the masculinity of the fishes by understanding the level of brain testosterone (T) and estradiol-17β(E₂). The gonadal hormones, E₂ and T have profound effects on specific cell groups in the brain. The presence of E₂ and T measured by RIA continuously in olfactory region of brain of Labeo rohita throughout a reproductive cycle. The sex steroids, E₂ and T were present all the months in the olfactory region both male and female fishes. E₂ levels in the males have revealed a hike in the levels during March and April (>180pg/mg tissue) and during November (>250pg/mg tissue) as compared to the other months characterized by less than 100pg/mg tissue. In females E₂ levels showed a different trend with the levels showing an abrupt increase during November (>300pg/mg tissue) followed by a decline during December (160pg/ml tissue), whereas the levels were very less (<90pg/mg tissue) during the other periods of reproductive cycle. The aromatase activity might have enhanced level of E₂ from T. In L. rohita, the breeding period starts from June and the vitellogenic period occur in the March and April which are characterized by decrease in E₂ and increase in testosterone levels in brain enabling male and female reproductive process.

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C. S. Blesson ¹, R. M. Inbaraj ¹

Affiliations
1 Department of Zoology, Madras Christian College, Tambaram, Chennai 600 059, IN

Abstract

Maturation inducing steroid (MIS) plays an important role in the final oocyte maturation (FOM) in fishes. It has been found out that 17α, 20β-dihydroxy-4-pregnen-3-one (17α, 20β-P) was the MIS in Catla catla. MIS acts thorugh a oocyte membrane receptor and promote the meiotic maturation.

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S. Dijju ¹, S. W. Santosh ¹, R. M. Inbaraj ¹

Affiliations
1 Department of Zoology, Madras Christian College, Tambaram, Chennai 600 059, IN

Abstract

Oocyte maturation in fishes is mediated by the maturation-inducing steroid (MIS) secreted by the follicular layer of the ovaries prior to the final stages of oocyte development. Li carps, 17,20β-P is found to be the MIS and is found to occur in both free and conjugated forms. The free and sulphated 17, 20β-P was measured by RIA in each sample collected in a complete reproductive cycle.

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