Central Cannabinoid Regulation of Food Intake in Chickens

Marijuana has been used for medicinal and recreational purposes for thousands of years. Many people think of marijuana in the context of an illegal drug. Because of the antimarijuana attitude, research with cannabinoids was neglected for a long time. Although this substance is related to social problems, scientists are interested in its action and possible medicinal properties. Since the identification of the structure of ∆tetrahydrocannabinol, the main psychoactive ingredient of marijuana, there has been increased interest in this compound. Following the discovery of two cannabinoid receptors, CB1 and CB2 receptors, it was determined that CB1 receptors are in high density in the central nervous system while CB2 receptors are found primarily in the immune system. The endogenous cannabinoid ligands, anandamide and 2arachidonoylglycerol, were observed in the central nervous system and peripheral tissues. Endocannabinoids differ from other “classical” neurotransmitters because they do not appear to be stored in synaptic vesicles, and they act as retrograde messengers within the brain. The endogenous cannabinoid signaling system includes cannabinoid receptors, their endogenous ligands called endocannabinoids, and the proteins for their synthesis and inactivation. The cannabinoid system appears to act as a neuromodulatory system. During the past ten years, the endogenous cannabinoid system has been implicated in a variety of physiological functions including pain reduction, motor regulation, learning, memory, and reward. Because obesity and eating disorders are prevalent, scientists are working at the molecular level to study the mechanisms controlling body weight and regulation of food intake. Several of the neuropeptides present in hypothalamic nuclei contribute to energy