Effects of diet and time of the day on serum and CSF leptin levels in Osborne-Mendel and S5B/Pl rats

Autor: George A. Bray, Asako Kageyama, Haruaki Kageyama, David A. York, Christy L. White, Yuri Ishihara
Rok vydání: 2004
Předmět:
Leptin
Male
STAT3 Transcription Factor
medicine.medical_specialty
Endocrinology
Diabetes and Metabolism
medicine.medical_treatment
Drug Resistance
Medicine (miscellaneous)
Suppressor of Cytokine Signaling Proteins
Rats
Mutant Strains
Eating
Endocrinology
Cerebrospinal fluid
Internal medicine
medicine
Animals
Insulin
Circadian rhythm
Obesity
RNA
Messenger
Saline
Dose-Response Relationship
Drug
business.industry
digestive
oral
and skin physiology
Diurnal temperature variation
Body Weight
Public Health
Environmental and Occupational Health
Dietary Fats
Circadian Rhythm
Diet
Rats
DNA-Binding Proteins
Repressor Proteins
Dose–response relationship
Cytokine
Suppressor of Cytokine Signaling 3 Protein
Trans-Activators
business
Corticosterone
hormones
hormone substitutes
and hormone antagonists
Food Science
Signal Transduction
Transcription Factors
Zdroj: Obesity research. 12(7)
ISSN: 1071-7323
Popis: Objective: To characterize the effects of dietary fat on the diurnal variation in serum and cerebrospinal fluid (CSF) leptin levels in Osborne-Mendel (OM) and S5B/Pl rats and quantitate the dose response to lower doses of leptin administered into the third cerebral ventricle. Research Methods and Procedures: Rats were fitted with implanted vascular ports or third ventricular cannulas and fed either laboratory chow or one of two semipurified high-fat or low-fat diets. Leptin and insulin were measured by immunoassay. Results: Serum leptin and insulin levels were positively correlated and had similar patterns of diurnal change. CSF leptin and insulin also had diurnal rhythms, with a peak at 7:00 am, but the diurnal oscillations of leptin and insulin were significantly lower in the S5B/Pl rats than the OM rats. Thus, the ratio of CSF to serum leptin was significantly higher in the S5B/Pl rats than in the OM rats. Dietary fat had no effect on these diurnal patterns. There was a right shift in the dose response to leptin in the OM rats compared with the S5B/P1 rats. S5B/P1 rats treated with leptin had higher signal transduction and translation (STAT-3) mRNA levels compared with pair-fed or saline injected S5B/P1 rats. Hypothalamic suppressors of cytokine signaling mRNA levels were not statistically different between the groups. Discussion: The higher CSF-to-serum leptin ratio in the S5B/P1 rats, the enhanced suppression of food intake and body weight with leptin injections, and the higher STAT-3 activity in these animals suggest that S5B/P1 rats are more sensitive to leptin than OM rats.
Databáze: OpenAIRE
Externí odkaz: