L-threonine injection into PPC modifies food intake, lateral hypothalamic activity, and sympathetic discharge
Monda, M.; Sullo, A.; De Luca, V.; Pellicano, M.P.; Viggiano, A.
American journal of physiology 273(2 Pt 2): R554-R559
1997
ISSN/ISBN: 0002-9513 PMID: 9277538 Document Number: 476285
Food intake and the firing rate of lateral hypothalamic neurons and nerves innervating interscapular brown adipose tissue (IBAT), along with IBAT and colonic temperatures, were monitored in male Sprague-Dawley rats fed a threonine-free diet. These variables were measured before and after a bilateral injection of L-threonine (2 nmol into each side) into the prepiriform cortex (PPC). The same variables were also monitored in 1) rats fed a threonine-free diet and injected with saline, 2) animals fed a standard diet and injected with L-threonine, and 3) rats fed a standard diet and injected with saline. The results showed that injection of L-threonine into PPC increases food intake and firing rate of lateral hypothalamic neurons, whereas it decreases the sympathetic discharge and body temperature in animals fed a threonine-free diet. No changes were found in the animals fed a standard diet. These findings suggest a correlation between 1) threonine level in the PPC and 2) lateral hypothalamic activity and sympathetic discharge to IBAT.