Association between pituitary adenylate cyclase-activating polypeptide and reproduction in the blue gourami

In order to gain a better understanding of the roles of pituitary adenylate cyclase-activating polypeptide (PACAP) in reproduction and growth, the expression of the PACAP gene during the reproduction cycle and its potential role in regulating gonadotropin and growth hormone (GH) gene transcription in blue gourami were investigated. The cDNA sequences of the full-length blue gourami brain PACAP and that of its related peptide (PRP) were acquired. PACAP cDNA had two variants, obtainable by alternative splicing: a long form encoding for both PRP and PACAP and a short form encoding only for PACAP. In females, mRNA levels of PACAP were very high only in individuals with oocytes in the maturation stage, as compared to levels in unpaired vitellogenic and non-vitellogenic fish. The PACAP mRNA levels in males were high only in nest builders, as opposed to in non-nest building males and juveniles. In pituitary culture cells from high vitellogenic females, PACAP38 (the 38 amino acid form) only brought about an increase in beta FSH levels. without altering GH and beta LH mRNA levels. On the other hand, in adult non-reproductive male pituitary cells, PACAP38 decreased the GH mRNA level. Based on these results, we propose that in the blue gourami, PACAP is involved in the final oocyte maturation stage in females, whereas in males, it is associated with sexual behavior. In addition, the effect of PACAP38 on pituitary hormone gene expression is different in females and males, indicating that PACAP38 is potentially a hypophysiotropic regulator of reproduction, which mediates pituitary hormone expression. (C) 2009 Elsevier Inc. All rights reserved.