Neonatal MSG administration eliminates hypothalamic lateralization of biogenic amines in chickens selected for divergent growth rates

Administration of monosodium glutamate (MSG) produces obesity in chickens and a line and sex dependent alteration in boby weight. This study was designed to determine neurochemical characteristics underlying these changes. Subcutaneous MSG injections (4 mg/g body weight) were administered to chickens differing in body composition due to their divergent selection for exponential growth rate. Injections were given on alternate days from day 0 (hatch) to 10 days of age. Amino acids, catecholamines, indolamines and related compounds were measured in bilateral tissue punches of the hypothalamus (HT) at 42 days of age. MSG significantly changed the lateralization of six amino acids (aspartate, serine, glutamate, glycine, taurine and valine), norepinephrine and dopamine. Significant three-way interactions (side*sex*treatment, side*line*treatment) were observed for the amino acids. MSG significantly raised the concentration of norepinephrine in the left HT by 55%, but decreased levels of dopamine in the right HT by 37%. Such changes in the HT could be indicative of changes in feeding behavior and/or metabolism in these animals