Effect of thyroid hormone excess and deficiency on serum thyrotropin in rats immunized passively with antiserum to somatostatin.

Abstract

SummaryPassive immunization or rats with antiserum to somatostatin (anti-SS) caused about a 2-fold increase in the basal serum TSH levels and a 1.5-fold rise in serum TSH after TRH, as compared to rats treated with normal sheep serum (NSS). When the basal and the TRH-stimulated TSH levels were suppressed to about half the control levels with 100 ng of T3/100 g BW, the neutralization of the endogenous somatostatin secretion with anti-SS significantly increased the basal as well as the post-TRH TSH levels. After administration of 200 ng of T3/100 g BW, the basal TSH levels in the anti-SS- and NSS-treated animals were the same, but, in response to TRH, the TSH levels rose significantly higher in the anti-SS-treated group. When higher doses of T3 (1 and 10 μg/100 g BW) were given, anti-SS failed to affect the basal or the post-TRH TSH levels. The elevated TSH levels 1 and 3 days after thyroidectomy were further increased by treatment with anti-SS as compared to NSS. The highly elevated level of TSH on the sev...