Energy metabolism and expression of uncoupling proteins 1, 2, and 3 after 21 days of recovery from intracerebroventricular mouse leptin in rats

• Published in: Physiology & behavior 2002-04, Vol.75 (4), p.473-482
• Main Authors: Gullicksen, P.Scott, Flatt, William P, Dean, Roger G, Hartzell, Diane L, Baile, Clifton A
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Body weight; Body Weight - drug effects; Calorimetry, Indirect; Carrier Proteins - biosynthesis; DNA Primers; Eating - drug effects; Energy metabolism; Energy Metabolism - drug effects; Food intake; Fundamental and applied biological sciences. Psychology; Injections, Intraventricular; Intermediate and energetic metabolism; Ion Channels; Leptin - administration & dosage; Leptin - pharmacology; Male; Membrane Proteins - biosynthesis; Membrane Transport Proteins; Metabolisms and neurohumoral controls; Mitochondrial Proteins; ob protein; Oxygen Consumption - drug effects; Protein Biosynthesis; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - biosynthesis; Thermogenesis - drug effects; Uncoupling Protein 1; Uncoupling Protein 2; Uncoupling Protein 3; Uncoupling proteins; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/S0031-9384(02)00652-2

Animals tend to maintain a lower body weight for an extended period after leptin administration has ended. This may be due to an enhancement of metabolic rate that persists after treatment withdrawal. Our objectives were to determine the period of leptin influence, when injected intracerebroventricularly (icv), on food intake, body weight, and energy expenditure. Additionally, the relationship between expressions of UCP1, UCP2, and UCP3 in different adipose tissues and heat production (HP) was assessed. Twenty-four adult male Sprague–Dawley rats were injected intracerebroventricularly with either 10 μg mouse leptin or 10 μl vehicle once per day for 4 days. At 24 h after the last injection, one group was killed while the other was placed in calorimetry chambers and monitored for 21 days of recovery. Leptin-injected rats exhibited an overshoot of food intake and respiratory quotient (RQ) during recovery, but body weight remained significantly lower up to 6 days. HP decreased in both groups over time but remained higher in the leptin group through recovery. However, retained energy (RE) was significantly greater than control for about 8 days. Overall, UCP expression was reduced at the end of recovery in parallel with the decline in HP. Brown adipose tissue (BAT) was the most responsive to leptin administration by dramatically changing UCP1 and UCP3 mRNA levels. Our data show that leptin has extended effects on energy expenditure but relieves control on food intake and RQ after treatment withdrawal. This translated into a reduced positive energy balance that slowed body weight recovery.