In vivo voltammetry study of the modulatory action of prolactin on the mesolimbic dopaminergic system.

The effects of an acute subcutaneous injection of ovine prolactin (PRL) or its vehicle on total motor activity and the extracellular levels of dopamine (DA), DOPAC and ascorbic acid (AA) in the nucleus accumbens were monitored simultaneously in freely behaving male rats. The neurochemical data were obtained by Differential Normal Pulse Voltammetry using electrochemically pretreated carbon fiber microelectrodes and numerical waveform analysis of the catechol peak. PRL treatment increased the extracellular levels of DA and DOPAC in the nucleus accumbens, which is consistent with previous reports using other methodologies. Furthermore, there was a concomitant decrease in the AA signals and motor activity. These findings suggest an antagonistic action of PRL on dopaminergic transmission in the mesolimbic system.