AJP - Endocrinology and Metabolism, Vol 247, Issue 1 126-E129, Copyright © 1984 by American Physiological Society
Prolactin profiles during estrous cycle and pregnancy in hamster as measured by homologous RIA
F. Talamantes, G. Marr, M. N. DiPinto and M. H. Stetson
The development of a homologous radioimmunoassay (RIA) for the measurement
of serum hamster prolactin (PRL) has facilitated our studies on monitoring
the secretion patterns of this hormone during different states of
reproduction. Four salient findings emerge from the present studies. First,
rapid cardiac puncture without anesthesia does not affect serum PRL levels
during selected times in the estrous cycle or during pregnancy. Second,
serum PRL levels during the estrous cycle describe a daily rhythm of PRL
release with maximum serum concentrations each day occurring in the
afternoon and the highest of these occurring on proestrus (day 4 of cycle).
Third, PRL release during pregnancy is characterized by a single surge each
day; although the time of maximum PRL release varies, levels increase
during the hours of darkness and decline to basal during the light. Fourth,
the amount of PRL released during pregnancy diminishes with time; on day 15
the total amount of PRL in the serum is less than 10% of that measured on
day 5.
