Expression of Melatonin Receptor Subtype Genes and its Impact on Reproductive Traits in Japanese Quail in Different Lighting Systems

Abstract

Melatonin receptors are G-protein coupled receptors which mediate the action of melatonin hormone. In this study, we investigated the effects of two different lighting systems, 23 h L: 1 h D (group I) and 12 h L: 12 h D (group II), on reproductive traits in Japanese Quail ( Coturnix coturnix japonica). As well as the expression pattern of three melatonin receptor subtypes, mRNA in ovaries and testes were analysed using quantitative real time PCR. The results revealed the expression of all three subtypes of melatonin receptors (MNTR1A, MNTR1B and MNTR1C) in ovaries and MNTR1B, MNTR1C in testes in both groups. Further, the expression of melatonin receptors was significantly higher in group II relative to group I. The fold change level of MNTR1C was 6.7 in ovaries and 3.1 in testes in short day light. Altered expression pattern of these genes associated with changes in Japanese Quail reproductive traits, while, Japanese Quail exposed to long day light started egg laying earlier than those in short day light. Egg weight and egg percentage increased significantly in group I compared to group II. The average of relative ovary and testis weight at six weeks of age were declined by 1.72 and 1.64 g, respectively, in group II. It was concluded that, different lighting system induced different expression levels of melatonin receptor genes accompanied with changes in reproductive traits in both sex of Japanese Quail.