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Insulin response in rats acutely exposed to cold
Canadian Journal of Physiology and Pharmacology
|August 1, 1984
Summary
Cold exposure significantly lowers insulin levels in rats by activating the sympathetic adrenal system. This effect is mediated by alpha-adrenergic inhibition of the pancreatic insulin response, impacting glucose regulation.
Area of Science:
- Endocrinology
- Physiology
- Thermogenesis
Background:
- Shivering thermogenesis is a critical physiological response to cold.
- The role of insulin in regulating energy metabolism during cold exposure is not fully understood.
Purpose of the Study:
- To investigate the impact of cold exposure on insulin levels in rats.
- To elucidate the mechanisms by which cold affects insulin secretion.
Main Methods:
- Rats were exposed to cold (4°C) or kept at thermoneutrality (25°C).
- Plasma insulin and glucose levels were measured.
- Adrenodemedullation and administration of alpha-adrenergic blocking agents (phentolamine) were used to explore the sympathetic nervous system's role.
Main Results:
- Cold exposure reduced plasma insulin levels by 50% without altering glucose concentrations.
- Adrenodemedullation partially restored insulin response to glucose, unless epinephrine was administered.
- Alpha-adrenergic blockade with phentolamine during cold stress enhanced insulin response to glucose.
Conclusions:
- Cold exposure depresses blood insulin levels via sympathetic adrenal system activation.
- Alpha-adrenergic pathways likely mediate the inhibition of pancreatic insulin secretion during cold stress.
- These findings highlight a novel regulatory mechanism of insulin during thermogenesis.