Sexual Differentiation in the Estradiol-17β in Olfactory Region of the Brain of Indian Major Carp Labeo rohita

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.