Thyroid status regulates CART but not AgRP mRNA levels in the rat hypothalamus.

We examined the effects of thyroid status on cocaine- and amphetamine-regulated transcript and agouti-related peptide expression in the rat hypothalamus. Hypo- and hyperthyroidism were induced in adult male rats, and the mRNA content of cocaine- and amphetamine-regulated transcript and agouti-related peptide was determined using in situ hybridization. Hyperthyroidism induces a reduction in cocaine- and amphetamine-regulated transcript mRNA levels in the paraventricular nucleus, without any change in the arcuate and dorsomedial nuclei and in the lateral hypothalamic area. On the other hand, hypothyroidism had not effect on cocaine- and amphetamine-regulated transcript expression in any of these nuclei. Agouti-related peptide expression in the arcuate nucleus was not affected by the thyroid status. These data indicate that the increments in food intake in hyperthyroidism could be mediated, at least in some extent, by a decreased expression, at the paraventricular nucleus of the hypothalamus, of the anorexigenic cocaine- and amphetamine-regulated transcript peptides.