AJP - Regulatory, Integrative and Comparative Physiology, Vol 252, Issue 2 290-R293, Copyright © 1987 by American Physiological Society
Suppressed serum prolactin in sinoaortic-denervated rats
N. Alexander, S. Melmed and M. Morris
We investigated the effect of arterial baroreceptor deafferentation on
serum and pituitary prolactin (PRL) and on catecholamines in median
eminence (ME) and anterior and posterior pituitaries. Male Wistar rats were
sinoaortic denervated (SAD) or sham operated (SO). Three days after surgery
serum prolactin, measured by radioimmunoassay, was suppressed in SAD rats
(-54%, P less than 0.05), and dopamine (DA) and norepinephrine (NE)
concentrations, measured by radioenzymatic or high-performance liquid
chromatography electron capture methods, were significantly reduced in ME
of SAD rats (NE, -54% P less than 0.005 and DA, -56% P less than 0.001).
Simultaneously, anterior pituitary of SAD rats had significant increases in
both catecholamines, whereas posterior pituitary showed no changes. Four
hours after surgery serum PRL was also reduced (-40%, P less than 0.05) in
SAD rats, but no changes in ME catecholamines were found. Mean arterial
pressure (MAP) and heart rate were measured before and after injection of
bromocriptine (0.5 mg/kg ip) in SAD and SO rats 3 days after surgery.
Bromocriptine markedly suppressed serum PRL in both groups and reduced MAP
from 144 +/- 10 to 84 +/- 5 and from 116 +/- 2 to 99 +/- 3 in SAD and SO
rats, respectively; heart rate was reduced in SAD rats. We conclude that
the SAD rat is a model of hypertension with suppressed serum PRL and that
interruption of arterial baroreceptor nerves suppresses PRL secretion
probably by modulating tuberoinfundibular turnover of catecholamines.
