ABSTRACT
This chapter highlights the mechanisms responsible for the control of food intake by animals. However, when fat stores and plasma levels of leptin and insulin are reduced, Agouti-related peptide/Neuropeptide Y neurons are activated and Pro-opiomelanocortin/cocaine-amphetamine regulated transcript neurons are inhibited, leading to increased food intake and weight gain. Most studies on food intake regulation have focused on Amino acids (AAs) that are not synthesized de novo in animal cells. Usually, high-fat diets reduce gastric and intestinal emptying, increase the concentrations of free-fatty acids in both the gastrointestinal tract and plasma, and promote the development of the fatty liver, thereby reducing food intake by animals. Conversely, a high concentration of serotonin, which can be brought about by activation of gastrointestinal serotonergic neurons, inhibits food intake by animals. Animals prefer highly digestible foods that are sources of energy and nutrients, and dislike poorly digestible foods that are bulky and low in energy or protein.
