Cadmium does not inhibit pulsatile prolactin secretion through TRH

This work was undertaken to analyse the effects of acute cadmium administra tion on the pulsatile pattern of prolactin release, in adult male rats. For this purpose, animals were cannulated 40 h before the experiment to allow a continuous blood withdrawal. Two hours after the administration of one do se of cadmium chloride (4.5 mg kg(1)), the pulsatile pattern of prolactin, during three hours, was studied. The effects of two pulses of thyrotropin-r eleasing hormone (TRH) (1 mu g per rat), given 60 and 120 min after startin g the period of blood sampling, were studied, The mean values of prolactin during the bleeding period and the absolute pulse amplitude were decreased by acute cadmium chloride administration, However, no changes in any other parameters of prolactin pulsatility were observed. TRH administration to co ntrol rats increased mean prolactin levels, and absolute and relative pulse amplitudes, but decreased the mean half-life of the hormone. In animals pr etreated with cadmium, TRH increased the mean levels of prolatin, and absol ute and relative amplitudes of the hormone pulses, No other parameter studi ed was changed by TRH in cadmium pretreated rats. These data suggest that a cute administration of cadmium did not inhibit the pulsatile prolactin rele ase through TRH.