Physiological response to long-term peripheral and central leptin infusion in lean and obese mice

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 94; no. 16; pp. 8878 - 8883
• Main Authors: Halaas, J.L. (The Rockefeller University, New York, NY.), Boozer, C, Blair-West, J, Fidahusein, N, Denton, D.A, Friedman, J.M
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 05-08-1997; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences of the USA
• Subjects: ADIPOSE TISSUES; Administration, Cutaneous; Animals; BAISSE DE POIDS; Biochemistry; BIOLOGICAL DIFFERENCES; Biological Sciences; Body weight; Body Weight - drug effects; BRAIN; CEREBRO; DEPLETION; Diet; DIFERENCIAS BIOLOGICAS; DIFFERENCE BIOLOGIQUE; Dosage; Dose response relationship; Dose-Response Relationship, Drug; ENCEPHALE; ENERGY METABOLISM; FOOD INTAKE; HORMONAS; HORMONE; HORMONES; INGESTION DE ALIMENTOS; Injections, Intraventricular; INTRACEREBROVENTRICULAR INFUSION; Leptin; LIPID METABOLISM; Mass; METABOLISME DES LIPIDES; METABOLISME ENERGETIQUE; METABOLISMO DE LIPIDOS; METABOLISMO ENERGETICO; MICE; Mice, Inbred C57BL; Obesity; Obesity - metabolism; Obesity - physiopathology; OVERWEIGHT; PEAU; PEPTIDE; PEPTIDES; PEPTIDOS; PIEL (ANIMAL); POLYPEPTIDES; PRISE ALIMENTAIRE (HOMME); Proteins - analysis; Pumps; RATON; REDUCCION DEL PESO; Rodents; SKIN; SOBREPESO; SOURIS; STRAIN DIFFERENCES; SUBCUTANEOUS INFUSION; SURPOIDS; TEJIDO ADIPOSO; TISSU ADIPEUX; Weight loss; WEIGHT REDUCTION
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.16.8878

Recent data have identified leptin as an afferent signal in a negative-feedback loop regulating the mass of the adipose tissue. High leptin levels are observed in obese humans and rodents, suggesting that, in some cases, obesity is the result of leptin insensitivity. This hypothesis was tested by comparing the response to peripherally and centrally administered leptin among lean and three obese strains of mice: diet-induced obese AKR/J, New Zealand Obese (NZO), and A(y). Subcutaneous leptin infusion to lean mice resulted in a dose-dependent loss of body weight at physiologic plasma levels. Chronic infusions of leptin intracerebroventricularly (i.c.v.) at doses of 3 ng/hr or greater resulted in complete depletion of visible adipose tissue, which was maintained throughout 30 days of continuous i.c.v. infusion. Direct measurement of energy balance indicated that leptin treatment did not increase total energy expenditure but prevented the decrease that follows reduced food intake. Diet-induced obese mice lost weight in response to peripheral leptin but were less sensitive than lean mice. NZO mice were unresponsive to peripheral leptin but were responsive to i.c.v. leptin. A(y) mice did not respond to subcutaneous leptin and were 1/100 as sensitive to i.c.v. leptin. The decreased response to leptin in diet-induced obese, NZO, and A(y) mice suggests that obesity in these strains is the result of leptin resistance. In NZO mice, leptin resistance may be the result of decreased transport of leptin into the cerebrospinal fluid, whereas in A(y) mice, leptin resistance probably results from defects downstream of the leptin receptor in the hypothalamus