AJP - Endocrinology and Metabolism, Vol 240, Issue 5 510-E518, Copyright © 1981 by American Physiological Society
LH responses to LHRH, DBcAMP, and 17 beta-estradiol in cultures derived from aged rats
L. K. Tang and F. Y. Tang
Effects of luteinizing hormone-releasing hormone (LHRH), N6,O2'-dibutyryl
adenosine 3',5'-cyclic monophosphate (DBcAmP), and 17 beta-estradiol (E2)
on LH responses were compared in 4-day-old pituitary cultures derived from
female rats (Fischer 344) of 9 and 31 mo of age. Pituitary LH contents were
similar in 5 X 10(5) freshly dispersed cells prepared from the two groups
of rats. LH release in response to a 4-h incubation with 10 nM LHRH was
virtually the same in cultures derived from 9- and 31-mo-old rats, 140 +/-
2 ng and 138 +/- 18 ng/4 h, respectively. In cultures derived from 9-mo-old
rats, incubation with 8 mM DBcAMP for 4 h significantly stimulated LH
release (286% of control level), and treatment with 10 nM E2 for 3 days
significantly increased both basal LH release and LH accumulation (sum of
LH contents in cells and medium) to 162 and 125% of control level,
respectively. Neither DBcAMP nor E2 affected cultures derived from the
31-mo-old rats. These results indicate that there is a difference in the LH
response to DBcAMP and E2 between cultures derived from 9- and 31-mo-old
rats. The loss of pituitary responsiveness to DBcAMP and E2 and the loss of
pituitary cyclicity in the aged female rat may be causally related.
