
plasma growth hormone concentration in the rat determined by
radioimmunoassay: influence of sex, pregnancy, lactation, anesthesia,
hypophysectomy and extrasellar pituitary transplants.
   the assay used is described in detail.  several experimental
conditions were studied, both to validate the
method and to determine factors which regulate gh secretion
in this species.  in fasting sprague-dawley rats
weighing 150-200 g, mean plasma gh concentration in
females was 94.2 17.3, and in males, 54.9 12.0 m g/ml.
gh levels in lactating rats were determined to be in
the normal range for females, thereby providing evidence
that this assay does not detect prolactin.  gh levels were
not elevated in pregnant rats.  hypophysectomy led to a
fall below detectable levels of gh.  intraocular pituitary
transplants failed to raise gh levels in hypophysectomized
hosts.  gh levels in male, but not in female, rats
are depressed by brief periods of ether anesthesia.  these
findings and the results of pituitary transplantation experiments
are further evidence that the nervous system
is involved in the regulation of gh secretion.
