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Abstract: 45
Sang-Young Chun1 *, Hyun-Jeong Park1 , Jin Lee1 , Wang Li1 , Hyuk-Bang Kwon1 *
Hormone Research Center, Dept. of Biology, Chonnam National University, Kwangju 500-757, Republic of Korea 1
Pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide with considerable homology to vasoactive intestinal peptide, has been shown to be stimulated by gonadotropins in the ovary. The present studies further evaluated the cell-type specific expression and gonadotropin regulation of PACAP type I receptor (PACAPR) in immature rat ovaries by Northern blotting, in situ hybridization and RNase protection assay. Northern blot analysis of ovaries obtained from prepubertal rats revealed the increased expression of PACAPR during prepubertal development. The major cell types expressing PACAPR messenger RNA (mRNA) were granulosa cells of large preantral follicles. Treatment with equine chorionic gonadotropin (eCG) to immature rats caused a decrease in ovarian PACAPR expression. In contrast, treatment with human chorionic gonadotropin (hCG) at 2 days after eCG treatment stimulated ovarian PACAPR mRNA within 6-9 h in granulosa cells of preovulatory follicles. Treatment with luteinizing hormone (LH) in cultured preovulatory follicles in vitro further confirmed the time- and dose-dependent stimulation of PACAPR by LH/hCG in granulosa cells of preovulatory follicles. Furthermore, RNase protection assay revealed that the short variant of ovarian PACAPR is the predominant form stimulated during prepubertal development and by gonadotropins. These results demonstrate the expression of PACAPR mRNA in granulosa cells of large preantral follicles and of preovulatory follicle stimulated by gonadotropins, and suggest that PACAP may play a role in follicle selection and ovulation as paracrine/autocrine factor.
This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.