Changes in orexin-A and neuropeptide Y expression in the hypothalamus of the fasted and high-fat diet fed rats.
This study was aimed to investigate the changes of orexin-A (OXA) and neuropeptide Y (NPY) expression in the hypothalamus of the fasted and high-fat diet fed rats. For the experiments, the male Sprague-Dawley (SD) rats were used as the model of high-fat diet-induced obesity. The mean loss of body weight (MLBW) did not show the linear pattern during the fasting; from 24 h to 84 h of fastings, the MLBW was not significantly changed. The numbers of OXA-immunoreactive (IR) neurons were decreased at 84 h of fasting compared with those in other five fasting subgroups. The NPY immunoreactivities in the arcuate nucleus (ARC) and the suprachiasmatic nucleus (SCN) observed at 84 h of fasting were higher than that observed at 24 h of fasting. The number of OXA-IR neurons of the LHA (lateral hypothalamic area) in the high-fat (HF) diet fed group was more increased than that of the same area in the normal-fat (NF) diet fed group. The NPY immunoreactivities of the ARC and the SCN were higher in HF group than those observed in the same areas of NF group. Based on these results, it is noteworthy that the decrease of the body weight during the fast was not proportionate to the time-course, implicating a possible adaptation of the body for survival against starvation. The HF diet might activate the OXA and the NPY in the LHA to enhance food intake.
Park
Eun Sung
ES
Department of Veterinary Anatomy and Cell Biology, College of Veterinary Medicine and Agricultural Biotechnology, Seoul National University, Seoul 151-742, Korea.
Yi
Seong Joon
SJ
Kim
Jin Sang
JS
Lee
Heungshik S
HS
Lee
In Se
IS
Seong
Je Kyung
JK
Jin
Hee Kyung
HK
Yoon
Yeo Sung
YS
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism; D004041:Dietary Fats; D004435:Eating; D005215:Fasting / Q000502:physiology*; D007026:Hypothalamic Area, Lateral / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism*; D007150:Immunohistochemistry / Q000662:veterinary; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D009478:Neuropeptide Y / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D009765:Obesity; D000068797:Orexins; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000378:metabolism
D004041:Dietary Fats; D047908:Intracellular Signaling Peptides and Proteins; D009478:Neuropeptide Y; D009479:Neuropeptides; D000068797:Orexins