Individual lactotropes release prolactin in a temporally divergent
and sexually dimorphic pattern.
Castano, Justo P., and L. Stephen Frawley.
Department of Cell Biology and Anatomy, Medical University of South
Carolina, Charleston, South Carolina 29425
APStracts 2:0126E, 1995.
Recent studies reveal that individual lactotropes vary in the amount
of prolactin (PRL) released from day to day, and that the magnitude
of these variations is gender-specific. In an attempt to further
elucidate the dynamics of hormone secretion by single cells, we have
investigated short-term variations in PRL release from male and
lactating female rat lactotropes. To this end, hormone release from
individual lactotropes was monitored at 12 min intervals for up to 2
h, using a modified version of the reverse hemolytic plaque assay. We
found that pituitary cells from both genders could release PRL in
either an intermittent or continuous mode, but that the former
pattern of secretion predominated for male lactotropes.
Interestingly, the mode of hormone secretion was tightly coupled
(p<0.001) to the amount of hormone released (continuous
>> intermittent), regardless of the gender of the pituitary
donor. The existence of gender-specific differences in secretory
modalities indicates that this fluctuating pattern of hormone
secretion by individual cells is not random but regulated, perhaps
through entrainment in vivo by gonadal steroids.
Received 17 April 1995; accepted in final form 30 May 1995.
APS Manuscript Number E179-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.