title: Effect of the gonadotrophin surge at pro-oestrus on steroidogenesis and gonadotrophin binding of preantral follicles in the cyclic hamster.
abstract: The present study describes the acute changes in steroids and human chorionic gonadotrophin (hCG) and FSH binding of preantral follicles induced by the gonadotrophin surges on the day of pro-oestrus. Preantral follicles were isolated by microdissection before (09.00-10.00 h), during (15.00-16.00 h) and after (21.00-22.00 h) the LH surge on pro-oestrus. Follicles at each time-period were pooled and steroid concentrations and gonadotrophin receptors determined. Before the LH surge, concentrations of progesterone and androstenedione were 40.8 +/- 6.1 (S.E.M.) and 10.7 +/- 3.9 fmol/follicle respectively. At the peak of the LH surge, progesterone and androstenedione concentrations in preantral follicles increased to 848 +/- 186 and 129 +/- 33 fmol/follicle respectively. Immediately after the LH surge, progesterone increased to 1238 +/- 97 fmol/follicle whereas androstenedione declined to 13.3 +/- 2.1 fmol/follicle. Oestradiol was less than 6 fmol/follicle throughout these periods. Binding of hCG and FSH to preantral follicles increased after the surge (hCG, 56 +/- 2.6 c.p.m./follicle; FSH, 29.8 +/- 4.0 c.p.m./follicle) when compared with values obtained before the surge (hCG, 15.8 +/- 4.0 c.p.m./follicle; FSH, 14.1 +/- 1.9 c.p.m./follicle). Also, hCG binding increased significantly (P less than 0.05) from 09.00 to 21.00 h (56 +/- 2.6 c.p.m./follicle). In order to ascertain which follicular compartments were affected by the LH and FSH surges on pro-oestrus, granulosa cells and thecae from preantral follicles were isolated and steroid concentrations and LH and FSH binding measured.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000735:Androstenedione / Q000096:biosynthesis; D000818:Animals; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D006224:Cricetinae; D004971:Estrus / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D006107:Granulosa Cells / Q000378:metabolism; D007986:Luteinizing Hormone / Q000502:physiology*; D006080:Ovarian Follicle / Q000378:metabolism*; D011359:Proestrus / Q000502:physiology*; D011374:Progesterone / Q000096:biosynthesis; D013799:Theca Cells / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D000735:Androstenedione; D011374:Progesterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone