Pituitary adenylate cyclase activating polypeptide messenger RNA in the paraventricular nucleus and anterior pituitary during the rat estrous cycle.
The neuropeptide pituitary adenylate cyclase activating polypeptide (ADCYAP 1, or PACAP) has been demonstrated to enhance gonadotropin-releasing hormone (GnRH)-induced gonadotropin secretion and regulate gonadotropin subunit gene expression in cultures of anterior pituitary cells. In the present study, we used in situ hybridization and real-time polymerase chain reaction to examine the expression of Pacap mRNA within the paraventricular nucleus (PVN) and anterior pituitary throughout the estrous cycle of the rat. Levels of luteinizing hormone in serum and pituitary gonadotropin subunit mRNAs were evaluated and displayed cyclic fluctuations similar to those reported previously. Pacap mRNA expression in the PVN and pituitary varied significantly during the estrous cycle, with the greatest changes occurring on the day of proestrus. Pacap mRNA levels in the PVN declined significantly on the morning of diestrus. During proestrus, PVN Pacap mRNA levels significantly increased 3 h before the gonadotropin surge and then declined. Pituitary expression of Pacap mRNA also varied on the afternoon of proestrus with a moderate decline at the time of the gonadotropin surge and a significant increase later in the evening. Expression of the mRNA species encoding the 288 amino acid form of follistatin increased significantly following the rise in pituitary Pacap mRNA, at the termination of the secondary surge in follicle-stimulating hormone beta (Fshb) gene expression. These results suggest that PACAP is involved in events before and following the gonadotropin surge, perhaps through increased gonadotroph sensitivity to GnRH and suppression of Fshb subunit expression through increased follistatin, as previously observed in vitro.
Moore
Joseph P
JP
Division of Endocrinology and Metabolism, Department of Medicine, University of Louisville, Louisville, Kentucky 40202, USA. jpmoor03@gwise.louisville.edu
Burger
Laura L
LL
Dalkin
Alan C
AC
Winters
Stephen J
SJ
D000818:Animals; D002940:Circadian Rhythm; D030762:Estrous Cycle / Q000378:metabolism*; D005260:Female; D037201:Follicle Stimulating Hormone, beta Subunit / Q000378:metabolism; D038681:Follistatin / Q000378:metabolism; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology; D009414:Nerve Growth Factors / Q000096:biosynthesis*; D009479:Neuropeptides / Q000096:biosynthesis*; D018377:Neurotransmitter Agents / Q000096:biosynthesis*; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
C495403:Adcyap1 protein, rat; D037201:Follicle Stimulating Hormone, beta Subunit; D038681:Follistatin; D009414:Nerve Growth Factors; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone