CADMIUM EXPOSURE INHIBITS THE PROLACTIN SECRETORY RESPONSE TO THYROTROPIN-RELEASING-HORMONE (TRH) INVITRO

In vitro dose response (0.1-100-mu-M) and time course studies were performed on anterior pituitary cells isolated from female Sprague-Dawley rats in the diestrous stage of the estrous cycle. All doses of TRH produced a significant increase in prolactin release by 5 min which was sustained for 30 min. Pretreatment with 25 or 50-mu-M Cd for 2 or 4 h produced a significant decrease in prolactin secretion during Cd exposure and in the prolactin secretory response to 1-mu-M TRH. These results suggest that Cd pretreatment alters the subsequent ability of the lactotrophs to respond to the physiological secretagogue TRH. This alteration does not appear to be due to a rebound phenomenon since basal prolactin release was the same in Cd-pretreated and control cells once the metal was removed. These results suggest that Cd pretreatment produces a significant decrease in prolactin release from the anterior pituitary lactotrophs in response to subsequent TRH stimulation in vitro.