SPX and Anxiety: Moreover, y334-Gal4 cells expressed CGRP (calca) and were enriched in spexin (spx), a neuropeptide implicated in anxiety, energy homeostasis, and nociception, and urotensin (uts1) and thyrotropin-releasing hormone (trh), which are part of the hypothalamic-pituitary-interrenal axis and are implicated in stress responses (55, 56).