Effect of environmental temperature on growth- and reproduction-related hormones gene expression in the female blue gourami (Trichogaster trichopterus)

Fish are ectothermic vertebrates, and their gonadal development and spawning are affected by changes in environmental temperature. Recent global temperature changes have increased the importance of studying the effect of temperature on reproduction. The aim of this paper was to study the effect of temperature on oogenesis and hormone gene expression related to reproduction and growth in the blue gourami female maintained under non-reproductive and reproductive conditions. In females under non-reproductive conditions, vitellogenic oocytes, gonadotropin-releasing hormone 3 (GnRH3), β luteinizing hormone (βLH) and growth hormone (GH) mRNA levels were affected by temperature changes. In females maintained under reproductive conditions with non-reproductively active males, a percentage of females in the final oocyte maturation (FOM) stage, pituitary adenylyl cyclase activating polypeptide (PACAP and PRP-PACAP), gonadotropins and GH mRNA levels were affected due to temperature changes. In females maintained under reproductive conditions with reproductively active males, also GnRH3 and insulin-like growth factor 1 (IGF-1) were affected by temperature changes. In conclusion, in blue gourami females, changes in environmental temperature affect oogenesis through changes in brain and pituitary hormone mRNA levels.