Effect of exogenous gonadotropins on gonadotrophs of the rat pituitary gland.
In the human in vitro fertilization (IVF) program a variety of superovulation regimens have been employed to promote follicular stimulation and the recruitment of supernumerary oocytes. This therapy, however, disturbs serum concentrations of estradiol and progesterone and may disrupt the normal feedback systems of the hypothalamo-pituitary axis. This study examines the effects of hyperstimulation on the pituitary gonadotrophs and circulating gonadotrophins. FSH and human chorionic gonadotropin (hCG) were administered to normal cycling female Sprague-Dawley rats (n = 12) in phase with their estrous cycle. Control rats (n = 12) were injected with saline. In both the experimental and control groups, six rats were mated on the evening of proestrus and killed 12 hr later, while six animals were killed prior to mating. Blood was collected at the time of sacrifice for radioimmunoassay. The pituitary glands were removed, processed for light microscopy and serially sectioned. Immunocytochemistry for LH and FSH was carried out to determine the area occupied by these cell types. Data were statistically analyzed. Findings were correlated with circulating levels of LH, FSH, estradiol and progesterone. RIA revealed that the concentration of LH, FSH, estradiol and progesterone were significantly different with respect to hyperstimulation and mating. In addition the area occupied by LH and FSH cells was significantly different with respect to both hyperstimulation and mating. Hyperstimulation affects gonadotroph content, as well as gonadotropin and sex steroid hormone concentrations and together with other factors, may disrupt the ideal environment required for implantation.
Thomadakis
C
C
Department of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. 055cleo@chiron.wits.ac.za
Kramer
B
B
D000818:Animals; D006063:Chorionic Gonadotropin; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000032:analysis*; D006801:Humans; D007106:Immune Sera; D007150:Immunohistochemistry; D007986:Luteinizing Hormone / Q000032:analysis / Q000187:drug effects*; D008297:Male; D010062:Ovulation Induction; D010902:Pituitary Gland / Q000737:chemistry / Q000187:drug effects*; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity
D006063:Chorionic Gonadotropin; D007106:Immune Sera; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone