Effect of pituitary adenylate cyclase-activating polypeptide (PACAP) on prolactin and somatolactin release from the goldfish pituitary in vitro.
Pituitary adenylate cyclase-activating polypeptide (PACAP) plays a role in mediating growth hormone and gonadotropin release in the teleost pituitary. In the present study, we examined the immunohistochemical relationship between PACAP nerve fibers and prolactin (PRL)- and somatolactin (SL)-producing cells in the goldfish pituitary. Nerve fibers with PACAP-like immunoreactivity (PACAP-LI) were identified in the neurohypophysis in close proximity to cells containing PRL-LI or SL-LI. Several cells with PRL-LI or SL-LI showed PACAP receptor (PAC(1)R)-LI. The cell immunoblot assay method was used to examine the effect of PACAP on PRL and SL release from dispersed goldfish pituitary cells. Treatment with PACAP increased the immunoblot area for PRL- and SL-LI from individual pituitary cells in a dose-dependent manner. The effect of PACAP on the expression of mRNAs for PRL and SL in cultured pituitary cells was also tested. Semiquantitative analysis revealed that the expression of SL mRNA, but not PRL mRNA, was increased significantly by the treatment with PACAP. The effect of PACAP on intracellular calcium mobilization in isolated pituitary cells was also investigated using confocal laser-scanning microscopy. The amplitude of Ca(2+) mobilization in individual cells showing PRL- or SL-LI was increased significantly following exposure of cells to PACAP. These results indicate that PACAP can potentially function as a hypophysiotropic factor mediating PRL and SL release in the goldfish pituitary.
Matsuda
Kouhei
K
Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan. kmatsuda@sci.u-toyama.ac.jp
Nejigaki
Yumika
Y
Satoh
Misuzu
M
Shimaura
Chika
C
Tanaka
Mio
M
Kawamoto
Keiichi
K
Uchiyama
Minoru
M
Kawauchi
Hiroshi
H
Shioda
Seiji
S
Takahashi
Akiyoshi
A
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002469:Cell Separation; D002478:Cells, Cultured; D005260:Female; D029941:Fish Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000378:metabolism*; D006054:Goldfish / Q000378:metabolism*; D008297:Male; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide / Q000235:genetics / Q000378:metabolism
D029941:Fish Proteins; D006023:Glycoproteins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010907:Pituitary Hormones; D012333:RNA, Messenger; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; C064448:somatolactin protein, fish; D011388:Prolactin; D002118:Calcium