Effect of immunization against the alpha N (alphaN) and alpha C (alphaC) peptides of the alpha43 subunit of inhibin on antral follicular growth and atresia and the patterns of gonadotrophin secretion in ewes.
The aims of this study were to investigate the role of inhibin in the distribution of healthy and atretic antral follicles and the secretion patterns of gonadotrophins. Ewes were actively immunized against either alphaN or alphaC of the inhibin alpha subunit with a primary injection and three booster injections. The control ewes received adjuvant only. The ovaries were removed either before or at 24 h after hCG administration in a synchronized follicular phase 48 h after removal of intravaginal progesterone pessaries. Morphological observations were made on every fifth section of the complete ovary (one per ewe) stained with haematoxylin and eosin. The mean number of corpora lutea observed per ewe with corpora lutea was not significantly different in ewes immunized against alphaN (2.4; alphaN-immunized ewes) or alphaC (2.6; alphaC-immunized ewes), and control (2.4) ewes, although some corpora lutea appeared cystic in the immunized ovaries. Compared with luteal phase concentrations, mean basal FSH concentrations in the early follicular phase were significantly increased in the alphaC-immunized ewes, similar in alphaN-immunized ewes and reduced in control ewes. No differences were observed in any of the LH parameters. Before hCG treatment, healthy antral follicles > 1 mm in diameter were not observed in any of the 52 follicles in the aC-immunized ewes and were observed in one of 37 follicles from alphaN-immunized ewes compared with 19 of 28 follicles in control ewes (P < 0.0001). For healthy antral follicles < 1 mm in diameter, there were 72 of 85 follicles in the alphaC-immunized ewes, 79 of 81 follicles in the alphaN-immunized ewes and 81 of 82 follicles in the control ewes. Similar results were obtained in healthy antral follicles < 1 mm in diameter at 24 h after hCG administration. In contrast to the control ewes, no healthy preovulatory follicles (> 6 mm in diameter) were observed in alphaN- and alphaC-immunized ewes either before or 24 h after hCG administration. Two newly formed corpora lutea from alphaC-immunized ovaries contained retained oocytes compared with none in control and alphaN-immunized ovaries. In conclusion, immunization against alphaN and alphaC may result in disruption of the normal processes of antral follicular growth and maturation independent of the concentrations of FSH and LH.
Dhar
A
A
Prince Henry's Institute of Medical Research, PO Box 5152, Clayton, Victoria 3168, Australia.
Doughton
B W
BW
Pruysers
E
E
Brown
R W
RW
Findlay
J K
JK
D000818:Animals; D000906:Antibodies / Q000097:blood; D017209:Apoptosis; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D003338:Corpus Luteum / Q000033:anatomy & histology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D005496:Follicular Atresia / Q000502:physiology*; D005498:Follicular Phase; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D006107:Granulosa Cells / Q000166:cytology; D007114:Immunization; D007117:Immunization, Secondary; D020287:In Situ Nick-End Labeling; D007265:Inhibins / Q000276:immunology*; D008183:Luteal Phase; D007986:Luteinizing Hormone / Q000378:metabolism; D006080:Ovarian Follicle / Q000502:physiology*; D010446:Peptide Fragments / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology; D012756:Sheep / Q000502:physiology*; D013799:Theca Cells / Q000166:cytology
D000906:Antibodies; D006063:Chorionic Gonadotropin; D006065:Gonadotropins, Pituitary; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C094377:inhibin-alpha subunit; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone