The Journal of endocrinology
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We have studied the secretion of TSH and prolactin from perifused rat anterior pituitary glands in vitro in response to single pulses of thyrotrophin releasing hormone (TRH) and KCl after prior exposure to TRH. Anterior pituitary fragments were incubated in normal medium or in medium containing 28 nmol TRH/1 for 20 h before perifusion. ⋯ In a similar series of experiments KCl (60 mmol/l) was administered to both control and TRH-'treated' pituitary tissue as a 3-min pulse; no significant differences in TSH responses or prolactin responses were observed. These data indicate that TRH desensitizes the pituitary thyrotroph to a subsequent TRH stimulus but has very little effect on prolactin secretion.