|Matteri, Robert - Bob|
Submitted to: Life Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/1996
Publication Date: N/A
Citation: N/A Interpretive Summary: Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) are reproductive hormones of the pituitary gland. The secretion of these hormones is very sensitive to environmental stress in adult animals. This phenomenon has not been studied in neonatal animals. The present study was conducted to evaluate the effect of rearing in a hot or cool thermal environment on LH and FSH secretion in neonatal pigs. Levels of LH and FS in the blood were evaluated. The function of the pituitary cells which produce LH and FSH also was determined with a cell culture technique. The hot environment was within the thermal comfort range of the neonatal pig, while the cool environment constituted a mild cold stress. The secretion of LH and FSH was lower in the cool environment, suggesting that, as in adult animals, adverse environmental conditions may reduce reproductive hormone secretion in the neonate. Thus, the secretion of pituitary LH and FSH may serve as a biochemical indicator of stress and well-being in the baby pig.
Technical Abstract: The present study evaluated the effect of a hot (cycling 27-32 deg C, 50- 70% RH) or cool (21 deg C, 55% RH) thermal environment (TE) on gonadotroph function in 3-week-old gilts (females). Pituitary cells from twelve gilts reared in each TE were cultured at a density of 250,000 cells/1 ml well and exposed to vehicle (culture medium); .1, 1, and 10 nM gonadotropin- releasing hormone (GnRH); 2 mM 8-Br-cAMP (cAMP); and 100 nM phorbol myristate acetate (PMA). Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion in culture were stimulated by GnRH and by pharmacological compounds (p < .0001). In vitro LH secretion was approximately three-fold higher in the hot, compared to the cool, TE group (p < .0001). Similarly, cellular LH content in the hot TE exceeded that in the cool TE (p < .005). The in vitro secretion of FSH and cellular FSH content were significantly elevated in the hot TE (p < .02). Serum LH concentrations in the hot and cool TE were 7.01 +/ 1.75 and 2.13 +/ .44 ng/ml, respectively (p < .02). Serum FSH concentrations were 6.38 +/ .53 and 4.59 +/ .28 ng/ml in the hot and cool TE, respectively (p < .01). The results of this study demonstrate that secretory responses of gonadotrophs in early postweaning pigs are influenced by chronic TE exposure. These differences in secretory activity may reflect levels of cellular gonadotropin available for release.