Abstract
Serum and pituitary FSH, LH and prolactin contents during the normal rat estrous cycles were assayed every two hours in adult female rats of Holtzman strain (lights on 5 a.m. to 7 p.m.), using NIAMD rat FSH, LH and prolactin radioimmunoassay kits.
The serum LH surge was observed from 6:00 p.m. to 7:00 p.m. on the proestrous day. The serum FSH surge was observed from 7:00 p.m. on the proestrous day to 5:00 a.m. on the estrous day. The serum prolactin concentrations also began to rise at 1:00 p.m. on the proestrous day, and remained at high levels until 10:00 a.m. on the estrous day.
The reduction in pituitary FSH, LH and prolactin content was simultaneously observed from 7:00 p.m. to 11:00 p.m. on the proestrous day.
These results not only comfirmed the data reported by Daane & Parlow (1971), but also demonstrated no diurnal rhythm on the first and second diestrous day. Dissociation between FSH and LH patterns seems to suggest the possibility that FSH and LH secretion may be controlled independently by the two distinct “Releasing factors, FRF and LRF”.
