Plasma levels of luteinizing hormone and gonadal maturation of lambari females under different photoperiods

Fernanda Keley Silva Pereira Navarro,Guilherme Crispim Hundley,Marina Apocalypse Nogueira Pereira,Rodrigo Diana Navarro,Luis David Solis Murgas

doi:10.1590/s0100-204x2013000800036

Fernanda Keley Silva Pereira Navarro, Guilherme Crispim Hundley + Show 3 more

Open Access

https://doi.org/10.1590/s0100-204x2013000800036

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Abstract

The objective of this work was to evaluate the effect of photoperiod on luteinizing hormone (LH) plasma levels and gonadal maturation of lambari females. One hundred and twenty adult lambaris, distributed into 12 aquaria of 20 L each, were randomly subjected to three different treatments, in a completely randomized design, and four replicates. Treatments were photoperiods in hours of light (L) and darkness (D): T1, 0 L:24 D; T2, 12 L:12 D; T3, 24 L:0 D. After 40 days, fish were subjected to fasting for 24 hours and, then, anesthetized. Immediately after slaughter, fish were weighed, and their gonads and livers were removed and weighed. Ovaries were weighed and immersed in Bouin's fixative solution for 24 hours and, then, kept in 70% alcohol until processing the material. Subsequently, the oocyte developmental stage was determined. No significant differences were observed between treatments for final weight, ovary weight, gonadosomatic index (GSI), hepatosomatic index (HSI) and LH levels. In all treatments, lambari females showed maturing ovaries with prevalence of vitellogenic oocytes. Photoperiod does not affect the LH levels and ovarian maturation in lambari females.

Highlights

Reproductive processes usually show endogenous rhythms triggered by environmental signals, to adjust the reproduction period and the development time of larvae and juveniles to an appropriate environment. numerous environmental factors such as temperature, photoperiod, rainfall, food and pheromones have been implicated as potential influencers of the reproductive activity of different species, the photoperiod probably accounts for the reproductive period of most fish (Sarkar & Upadhyay, 2011)
The gonadotropin‐releasing hormone (GnRH) stimulates the release of FSH and luteinizing hormone (LH) by the adenohypohysis, which stimulates the release of gonadotropins by the anterior pituitary
Female lambaris under different photoperiods showed no significant difference for gonad weight and gonadosomatic index (GSI) (Table 1)

Summary

Introduction

Reproductive processes usually show endogenous rhythms triggered by environmental signals, to adjust the reproduction period and the development time of larvae and juveniles to an appropriate environment. numerous environmental factors such as temperature, photoperiod, rainfall, food and pheromones have been implicated as potential influencers of the reproductive activity of different species, the photoperiod probably accounts for the reproductive period of most fish (Sarkar & Upadhyay, 2011). Reproductive processes usually show endogenous rhythms triggered by environmental signals, to adjust the reproduction period and the development time of larvae and juveniles to an appropriate environment. The photoperiod, an important factor in gonadal maturation of fish, has a direct effect on the hypothalamic‐pituitary‐gonadal axis of teleost fish, stimulating or inhibiting the production of gonadotropin‐releasing hormone (GnRH), pituitary hormones FSH stimulates gonadal growth, gametogenesis and the entry of vitellogenin into the oocyte, while LH is important for the final maturation of oocytes and spawning. The influence of gonadotropin on the gonad varies during the maturation process, so that the gonads may be more or less responsive to gonadotropin, and the effect varies over gonadal development (Navarro & Navarro, 2012)

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