Developmental changes in hypothalamic leptin receptor: relationship with the postnatal leptin surge and energy balance neuropeptides in the postnatal rat

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 296; no. 3; pp. R631 - R639
• Main Authors: Cottrell, E. C, Cripps, R. L, Duncan, J. S, Barrett, P, Mercer, J. G, Herwig, A, Ozanne, S. E
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.03.2009
• Subjects: Animals; Animals, Newborn - physiology; Arcuate Nucleus of Hypothalamus - growth & development; Arcuate Nucleus of Hypothalamus - metabolism; Blood Glucose - metabolism; Brain; Cytokines; Developmental Physiology and Pregnancy; Energy Metabolism - physiology; Enzyme-Linked Immunosorbent Assay; Ependyma - cytology; Ependyma - metabolism; Female; Hypothalamus - growth & development; Hypothalamus - metabolism; In Situ Hybridization; Insulin - blood; Leptin - metabolism; Nervous system; Neurons; Neuropeptides - metabolism; Peptides; Rats; Rats, Wistar; Receptors, Leptin - metabolism; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins - biosynthesis; Suppressor of Cytokine Signaling Proteins - genetics; Third Ventricle - cytology; Third Ventricle - growth & development; Third Ventricle - metabolism
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.90690.2008

1 Institute of Metabolic Science, Metabolic Research Laboratories, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK; and 2 Division of Obesity and Metabolic Health, University of Aberdeen, Rowett Institute of Nutrition and Health, Bucksburn, Aberdeen, UK Submitted 11 August 2008 ; accepted in final form 22 December 2008 In the adult brain, leptin regulates energy homeostasis primarily via hypothalamic circuitry that affects food intake and energy expenditure. Evidence from rodent models has demonstrated that during early postnatal life, leptin is relatively ineffective in modulating these pathways, despite the high circulating levels and the presence of leptin receptors within the central nervous system. Furthermore, in recent years, a neurotrophic role for leptin in the establishment of energy balance circuits has emerged. The precise way in which leptin exerts these effects, and the site of leptin action, is unclear. To provide a detailed description of the development of energy balance systems in the postnatal rat in relation to leptin concentrations during this time, endogenous leptin levels were measured, along with gene expression of leptin receptors and energy balance neuropeptides in the medial basal hypothalamus, using in situ hybridization. Expression of leptin receptors and both orexigenic and anorexigenic neuropeptides increased in the arcuate nucleus during the early postnatal period. At postnatal day 4 (P4), we detected dense leptin receptor expression in ependymal cells of the third ventricle (3V), which showed a dramatic reduction over the first postnatal weeks, coinciding with marked morphological changes in this region. An acute leptin challenge robustly induced suppressor of cytokine signaling-3 expression in the 3V of P4 but not P14 animals, revealing a clear change in the location of leptin action over this period. These findings suggest that the neurotrophic actions of leptin may involve signaling at the 3V during a restricted period of postnatal development. neonate; hypothalamus; development Address for reprint requests and other correspondence: E. Cottrell, Institute of Metabolic Science, Metabolic Research Laboratories, Univ. of Cambridge, Box 289, Level 4, Addenbrooke's Hospital, Cambridge CB2 OQQ, United Kingdom (e-mail: ecc35{at}cam.ac.uk )