Central Thyrotropin-Releasing Hormone Infusion Opposes Cardiovascular and Metabolic Suppression during Caloric Restriction
| Autor: | W. David Knight, Almetra D. Parsons, Steven J. Swoap, J. Michael Overton |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Male
endocrine system medicine.medical_specialty endocrine system diseases Endocrinology Diabetes and Metabolism Radioimmunoassay Thyrotropin-releasing hormone Blood Pressure Motor Activity Biology Cardiovascular System Drug Administration Schedule Rats Sprague-Dawley Eating Cellular and Molecular Neuroscience Endocrinology Heart Rate Internal medicine medicine Animals Premovement neuronal activity Thyrotropin-Releasing Hormone Caloric Restriction Injections Intraventricular Analysis of Variance Endocrine and Autonomic Systems Drug Administration Routes Leptin Body Weight Caloric theory Rats Hypothalamus Energy Metabolism Thermogenesis hormones hormone substitutes and hormone antagonists Hormone Endocrine gland |
| Zdroj: | Neuroendocrinology. 83:69-76 |
| ISSN: | 1423-0194 0028-3835 |
| DOI: | 10.1159/000094004 |
| Popis: | Inhibition of hypothalamic thyrotropin-releasing hormone (TRH) neuronal activity is a well-established adaptation to caloric restriction (CR) that suppresses pituitary secretion of thyroid-stimulating hormone, but may also participate in modulation of autonomic function. Thus, we hypothesized that decreased hypothalamic TRH activity contributes to CR-induced bradycardia and decreased metabolic rate. To test this hypothesis, male Sprague-Dawley rats were instrumented with telemetry devices for measurement of heart rate (HR) and blood pressure (BP) and a lateral intracerebroventricular (i.c.v.) guide cannula for central infusions. After recovery, rats were housed in metabolic chambers and given either ad libitum(ad-lib) or CR treatments for 7 days; half of each diet group was then given continuous i.c.v. infusions of TRH (25 nmol/h) or saline (0.25 µl/h) for 7 days via osmotic pump. This dose of TRH did not significantly alter peripheral free T4 levels. In ad-lib rats, TRH infusion produced small reductions in food intake and small increases in HR and BP over saline-infused controls. In CR rats, TRH infusion resulted in an increase in HR and also energy expenditure over saline-infused controls. These results support the hypothesis that suppression of central TRH activity contributes to the homeostatic suppression of energy expenditure and HR observed during CR. |
| Databáze: | OpenAIRE |
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