Dopamine transporter mRNA in neurons of the rat hypothalamus.

The membrane-bound dopamine transporter (DAT) protein terminates dopaminergic neurotransmission by rapid reaccumulation of dopamine into presynaptic nerve endings. The distribution of neurons expressing DAT mRNA was investigated in the rat hypothalamus using in situ hybridization histochemistry and oligonucleotide probes to sequences of rat DAT mRNA. DAT mRNA-containing cell bodies were demonstrated in the ventral aspect of the periventricular nucleus (A14 dopamine cell group), in the zona incerta (A13), in the dorsomedial part of the arcuate nucleus (A12), and in scattered regions of the posterior hypothalamus. There was no labelling in magnocellular neurons of the supraoptic or paraventricular nuclei, or in neurons of the ventrolateral division of the arcuate nucleus, areas previously shown to contain the dopamine-synthesizing enzyme tyrosine hydroxylase. The results suggest that hypothalamic dopamine neurons have an active uptake mechanism for dopamine, however, that DAT mRNA levels may be considerably lower than those encountered in the ventral midbrain.