AGRP and Anorexia: Finally, hypothalamic assessment of AN candidate genes in these groups revealed long-lasting downregulation of AgRP and upregulation of Htr1a, resembling the expression patterns found in the original control ABA group (Fig. 6i and Fig. 1j) and further confirming the central role played by the hypothalamic melanocortin and serotonin systems in anorexia.