Tail-pinch-induced hyperphagia in weanling rats with dorsomedial hypothalamic lesions

✍ Scribed by Lee L. Bernardis; Larry L. Bellinger; Jack K. Goldman

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 554 KB
• Volume: 5
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490050109

✦ Synopsis

Abstract

Dorsomedial hypothalamic lesions (DMNL) were produced in 26‐day‐old and 44‐day‐old male rats. Sham‐operated rats served as controls. Tail‐pinching (TP) was performed for five minutes at a time over two periods: the first TP period of six sessions each from post‐operative day 1 to day 17 and the second TP period of eight sessions from post‐operative day 18 to day 35. Three equicloric diets, high‐carbohydrate, high‐fat, and high‐protein, were presented ad libitum in pellet form during the TP sessions. Lab chow was available ad libitum in the home cages. Rats with DMNL at age 26 days did not show TP‐induced hyperphagia and HCD preference compared to the controls until the second TP period. In rats lesioned at age 44 days, TP‐induced hyperphagia and HCD‐preference (compared with controls) became evident immediately after the operation. In the home cages (lab chow), DMNL rats showed a decline in food intake from the first to the second TP period, while the sham‐operated controls showed an increase. TP‐induced hyperphagia in the rat with DMNL does not appear to be caused by some arousal‐related process as has been shown for the rat with lateral hypothalamic lesions. Lesions in the nigrostriatal system have been reported to attenuate TP‐induced feeding, while the present study indicates that lesions in the DMN enhance it. This suggests that fibers in the central nervous system may be involved in facilitation or inhibition of TP‐induced eating.