Molecular cloning of growth hormone-releasing hormone/pituitary adenylyl cyclase-activating polypeptide in the frog Xenopus laevis: brain distribution and regulation after castration.
Pituitary adenylyl cyclase-activating peptide (PACAP) appears to regulate several neuroendocrine functions in the frog, but its messenger RNA (mRNA) structure and brain distribution are unknown. To understand the potential role of PACAP in the male frog hypothalamic-pituitary-gonadal axis, we cloned the frog Xenopus laevis PACAP mRNA and determined its distribution in the brain. We then analyzed the castration-induced alterations of mRNA expression for PACAP and its selective type I receptor (PAC1) in the hypothalamic anterior preoptic area, a region known to regulate reproductive function. The PACAP mRNA encodes a peptide precursor predicted to give rise to both GH-releasing hormone and PACAP. The deduced peptide sequence of PACAP-38 was nearly identical to that of human PACAP with one amino acid substitution. Abundant PACAP mRNA was detected in the brain, but not several other tissues, including the testis. In situ hybridization revealed strong expression of the PACAP gene in the dorsal pallium, ventral hypothalamus, and nuclei of cerebellum. PACAP mRNA signals were weak to moderate in the hypothalamic anterior preoptic area and were absent in the pituitary. Castration induced an increase in the expression of PACAP and PAC1 receptor mRNAs in the hypothalamic anterior preoptic area after 3 days. Replacement with testosterone prevented the castration-induced changes. These results provide a molecular basis for studying the physiological functions of PACAP in frog brain and suggest that PACAP may be involved in the feedback regulation of hypothalamic-pituitary-gonadal axis.
Hu
Z
Z
Department of Psychiatry, Mental Retardation Research Center, University of California School of Medicine, Los Angeles 90024-1759, USA.
Lelievre
V
V
Tam
J
J
Cheng
J W
JW
Fuenzalida
G
G
Zhou
X
X
Waschek
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001923:Brain Chemistry / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005246:Feedback / Q000502:physiology; D013007:Growth Hormone-Releasing Hormone / Q000096:biosynthesis*; D006801:Humans; D017403:In Situ Hybridization; D007814:Larva; D008297:Male; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000096:biosynthesis*; D009919:Orchiectomy; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011301:Preoptic Area / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013739:Testosterone / Q000494:pharmacology; D014018:Tissue Distribution; D015854:Up-Regulation; D029867:Xenopus Proteins; D014982:Xenopus laevis
C495404:ADCYAP1 protein, Xenopus; C495401:ADCYAP1 protein, human; D018076:DNA, Complementary; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D029867:Xenopus Proteins; D013739:Testosterone; D013007:Growth Hormone-Releasing Hormone