Pituitary adenylyl cyclase activating polypeptide (PACAP) belongs to the vasoactive intestinal polypeptide (VIP)/secretin/glucagon superfamily. PACAP is present in two forms, PACAP-38 and PACAP-27, and binds to three guanine-regulatory (G) protein-coupled receptors (PAC1, VPAC1, and VPAC2). PACAP is expressed in the central and peripheral nervous systems with high PACAP levels found in the hypothalamus, a brain region involved in feeding and energy homeostasis. PAC1 receptors are high-affinity and PACAP-selective receptors, while VPAC1 and VPAC2 receptors show a comparable affinity to PACAP and VIP. PACAP and its receptors are expressed in the central and peripheral nervous systems, with moderate to high expression in the hypothalamus, amygdala, and other limbic structures. Consistent with their expression, PACAP is involved in several physiological responses and pathological states. A growing body of literature suggests that PACAP regulates food intake in laboratory animals. However, there is no comprehensive review of the literature on this topic. Thus, the purpose of this article is to review the literature regarding the role of PACAP and its receptors in food intake regulation and to synthesize how PACAP exerts its anorexic effects in different brain regions. To achieve this goal, we searched PubMed and reviewed 68 articles regarding the regulatory action of PACAP on food intake. Here, we present the literature regarding the effect of exogenous PACAP on feeding and the role of endogenous PACAP in this process. We also provide evidence regarding the effect of PACAP on the homeostatic and hedonic aspects of food intake, the neuroanatomical sites where PACAP exerts its regulatory action, which PACAP receptors may be involved, and the role of various signaling pathways and neurotransmitters in hypophagic effects of PACAP.

Alcohol use disorder (AUD) represents major public and socioeconomic issues. Alcohol exerts its phar-macological effects by altering different neurotransmitter systems, such as g-aminobutyric acid (GABA), glutamate, opioids, etc. Recent evidence suggests that the dynorphin (DYN)/kappa opioid receptor (KOR) system mediates the negative affective states associated with alcohol withdrawal. This system is also in-volved in stress-mediated alcohol intake in alcohol-dependent subjects. The DYN/KOR system probably exerts its action in the central nucleus of the amygdala (CeA) to mediate the negative affective states as-sociated with alcohol withdrawal. This article aims to review the current literature regarding the role of the DYN/KOR system in the actions of alcohol. We first review the literature regarding the effect of alcohol on the level of the peptide and its receptor, and the role of the endogenous DYN/KOR system in alcohol reward and negative affective states associated with alcohol withdrawal is then discussed. We also review the literature regarding the effects of KOR ligands on these processes.