| Abstrakt: |
This study was designed to determine if luteal cell receptors for luteinizing hormone/human chorionic gonadotropin (LH/hCG) contribute to the previously demonstrated abnormal function of induced corpora lutea (CL) in gilts. Twenty-five prepuberal (P) gilts, induced to ovulate with 1,500 IU pregnant mare serum gonadotropin followed 72 h later with 500 IU hCG (d 0 = day of hCG), and 22 mature (M) gilts that had displayed two or more estrous cycles were ovariectomized (OVX) on d 10, 14, 18, 22 or 26 after the onset of estrus. All gilts except those OVX on d 10 were hysterectomized between d 6 and 9 to ensure luteal maintenance. The CL were stored at −196° C until determination of LH/hCG receptor number and dissociation constant (KD) by saturation analysis. Receptor number was greater for M than for P gilts on d 14 (P< .07) and d 18 (P< .01). The KDwas greater in M than in P gilts on d 14 (P< .01) and d 18 (P< .0001). The LH/hCG receptor number and KDof P gilts remained the same throughout the days studied. The LH/hCG receptor number (fmol/mg protein) of M gilts was elevated on d 10, 14, and 18 (50.8, 50.4 and 51.4, respectively) and decreased on d 22 (26.5) and d 26 (25.4) to values similar to those of P gilts. In M gilts, KDincreased on d 14, remained high on d 18 and decreased on d 22. We suggest that abnormal function of induced CL in P gilts may be due to an elevated LH receptor number. |
