Comparison of the temporal programs regulating tyrosine hydroxylase and enkephalin expressions in TIDA neurons of lactating rats following pup removal and then pup return.

Dopamine (DA) and enkephalin (ENK) release from the tuberoinfundibular dopaminergic neurons (TIDA) into the hypophysial portal circulation is fundamentally different under non-lactating and lactating conditions. The aim of this experiment was to compare the effect of a brief interruption then resumption of suckling on the temporal program of tyrosine hydroxylase (TH; rate-limiting enzyme of dopamine synthesis) and ENK regulation in dams. On post partum day 10, pups were removed for a 4-h period from a group of the dams then returned for 4- and 24-h periods.