Agents with orexigenic effects include the following:

Ghrelin is an appetite inducing (orexigenic) hormone produced in the stomach and the upper portion of the small intestine.

An orexigenic, or appetite stimulant, is a drug, hormone, or compound that increases appetite.

They activate cells in the arcuate nucleus that include the orexigenic neuropeptide Y (NPY) neurons.

This hormone acts in the arcuate nucleus and inhibits the AgRP/NPY neuron from releasing orexigenic peptides.

It is classified as a noradrenergic and specific serotonergic antidepressant (NaSSA) and has antidepressant, anxiolytic, hypnotic, antiemetic, orexigenic, and antihistamine effects.

Melanin-concentrating hormone (MCH) is a cyclic 19-amino acid orexigenic hypothalamic peptide originally isolated from the pituitary gland of teleost fish where it controls skin pigmentation.

All of these are members of a family of signalling lipids called N-acylethanolamines, which also includes the noncannabimimetic palmitoylethanolamide and oleoylethanolamide, which possess anti-inflammatory and orexigenic effects, respectively.

Masashi Yanagisawa and colleagues at the University of Texas Southwestern Medical Center at Dallas, coined the term orexin to reflect the orexigenic (appetite-stimulating) activity of these hormones.

This inhibition is hypothesized to then reduce output from orexigenic neurons to amineregic, cholinergic, and glutamatergic arousal pathways of the brain, thus decreasing the activity of those pathways, and therefore brain arousal.

Janda and colleagues then showed that an active vaccine against the orexigenic hormone ghrelin can slow the rate of weight gain, and adiposity, and do this through an entirely metabolic mechanism, as food intake was unchanged.

Behaviorial assays in orexigenic studies, in which rats are the model organism, have been done collectively with immunoassays and in situ hybridization studies to confirm that elevating NPYergic activity does indeed increase food intake.

Pyroglutamylated RFamide peptide receptor also known as orexigenic neuropeptide QRFP receptor or G-protein coupled receptor 103 (GPR103) is a protein that in humans is encoded by the QRFPR gene.

Alteration of control loop: High levels of leptin, a hormone secreted by adipocytes, block the release of neuropeptide (NPY), which is the most potent feeding-stimulatory peptide in the hypothalamic orexigenic network, leading to decreased energy intake, but high metabolic demand for nutrients.

Nesfatin-1 immunoreactive neurons in the ARC are activated by simultaneous injection of ghrelin and desacyl ghrelin, nesfatin-1 may be involved in the desacyl ghrelin-induced inhibition of the orexigenic effect of peripherally administered ghrelin in freely fed rat.