c-Fos expression in hypothalamic nuclei of food-entrained rats

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 286; no. 1; pp. 158 - R165
• Main Authors: Angeles-Castellanos, Manuel, Aguilar-Roblero, Raul, Escobar, Carolina
• Format: Journal Article
• Language: English
• Published: United States 01.01.2004
• Subjects: Animal Feed; Animals; Circadian Rhythm; Fasting - physiology; Feeding Behavior - physiology; Hypothalamus - metabolism; Immunohistochemistry; Male; Proto-Oncogene Proteins c-fos - metabolism; Rats; Rats, Wistar; Tissue Distribution
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00216.2003

1 Departamento de Anatomía, Facultad de Medicina, 2 Departamento de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City DF 04510, Mexico Submitted 22 April 2003 ; accepted in final form 18 August 2003 The present study aimed to identify the hypothalamic nuclei involved with food entrainment by using c-Fos-like immunoreactivity (c-Fos-IR) as a marker of functional activation. We studied rats entrained 3 wk to restricted feeding schedules (RF), their ad libitum (AL) controls, and the persistence of c-Fos-IR temporal patterns in entrained-fasted rats. In addition, we included 22-h fasting and 22-h fasting-refeeding groups as controls of fasting and refeeding acute effects. Diurnal patterns of c-Fos-IR were observed in the tuberomammilar nucleus (TM) and suprachiasmatic nucleus (SCN) in AL rats. In all nuclei, except the SCN and ventromedial nucleus (VMH), restricted feeding schedules imposed a temporal pattern of increased c-Fos-IR around mealtime. An increase in c-Fos-IR before and after meal time was observed in dorsomedial nucleus (DMH), lateral nucleus (LH), perifornical area (PeF), and TM, and a marked increase was observed in the paraventricular nucleus (PVN) after feeding. Food-entrained c-Fos-IR patterns persisted after 3 days in fasting in DMH, LH, and PeF. Present data suggest that FEO might not rely on a single nucleus and rather may be a distributed system constituted of interacting nuclei in which the PVN is mainly involved with the response to signals elicited by food ingestion and, therefore, with the entraining pathway. We can suggest that the PeF and TM may be involved with the arousal state during food anticipation and the DMH and LH with the time-keeping mechanism of FEO or its output. circadian rhythms; entrainment; food-entrained oscillator; food anticipatory activity Address for reprint requests and other correspondence: C. Escobar, Departamento de Anatomía, Edificio B 4° piso, Facultad de Medicina, UNAM, Ciudad Universitaria, México DF 04510, México (E-mail: cescobar{at}ifisiol.unam.mx ).