Plasma levels of luteinizing hormone and of growth hormone in ewe lambs with feed restriction
1991
Recabarren M, Sergio (Concepcion Univ., Chillan (Chile). Dept. de Medicina Veterinaria) | Ramirez R, Jaime | Manriquez A, Luis | Orellana B, Patricio | Parilo V, Jose A.
Plasma levels of LH and GH were measured in blood samples obtained from jugular vein at 15 min intervals for 6 h in control and in food restricted ewe lambs on day 63 of 70 days of food restriction. Analysis of plasma levels of LH showed no differences in number of pulses, amplitude of LH pulses, mean total LH level and interpulse interval among both groups of animals while total mean level of GH was higher in food restricted ewe lambs. A test of pituitary responsiveness to four pulses of LHRH was performed one week later showing no difference of the responsiveness expressed as area under the response curve. Metabolic disturbances generated by the food restriction was reflected in low glucose plasma level, total plasma protein and body weight and high plasma urea concentration. These results suggest that metabolic changes may not be deep enough to alter the hypothalamic control of endogenous pulsatile LH and GH secretion or that the inhibitory photoperiod when the experiments were performed masked any differences in hormone secretion due to the food restriction
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