Correlation of luteinizing hormone surges with XXXX nuclear and progestin cytosol receptors in the hypothalamus and pituitary gland. II. Temporal @entity53 effects.

@entity172 @entity1420 @entity53 @entity134 @entity35
In these studies we examined the temporal parameters of @entity53 (E2) priming required before @entity1420 (P4) amplifies the surge release of luteinizing hormone (LH) in short-term ovariectomized (OVX) @entity35 . Thereafter, we correlated the time of appearance and concentrations of @entity172 nuclear (E2Rn) and progestin cytosol (PRc) receptors in brain regions known to be involved in the surge release of LHRH. @entity134 receptor concentrations were also measured in the pituitary gland. 1 week after OVX (day 0), Silastic capsules containing E2 (150 micrograms/ml in oil s.c.) were placed at 09.00 h. The serum E2 concentrations produced by these capsules peaked (41 +/- 2.1 pg/ml) at 10.00 h on day 0 and declined thereafter to values which ranged between 19 and 10 pg/ml on days 1 through 4. Some of these E2-treated @entity35 also received 2 P4-containing Silastic capsules (50 mg/ml s.c. in oil) at 09.00 h on either days 0, 1, 2, 3 or 4. Serum P4 concentrations produced by such capsules were 9.3 +/- 0.5 ng/ml. Blood was collected sequentially at 09.00 h and at hourly intervals from 12.00-18.00 h on the day that the animals received the P4 capsules and 10.00 and 15.00 h samples also were taken from each group the next day. LH surges occurred in these E2-treated @entity35 in the afternoons of days 2-4, but not on days 0 and 1. P4 treatment on day 1 elicited an LH surge and on days 2-4 it amplified plasma LH surge concentrations and advanced by 1 h the time of release of this gonadotropin.(ABSTRACT TRUNCATED AT 250 WORDS)
