Hyperglycaemia: imitating Claude Bernard's piqûre with drugs

Area of Science:

• Neuroendocrinology
• Physiology

Background:

• Hyperglycemia is a condition of elevated blood glucose levels.
• Adrenaline (epinephrine) is typically associated with acute stress responses.

Purpose of the Study:

• To investigate the effects of various drugs administered centrally on blood glucose levels.
• To explore a potential novel physiological role for adrenaline in glucose homeostasis.

Main Methods:

• Administration of diverse drugs (e.g., opioids, neuropeptides, receptor antagonists) into the cerebral ventricles or cisterna magna of unanesthetized cats, rabbits, and rats.
• Observation of induced hyperglycemia and inference of underlying mechanisms.

Main Results:

• Prolonged hyperglycemia was consistently observed following central drug administration.
• The observed hyperglycemia is likely mediated by a sustained, low-level release of adrenaline from the adrenals, triggered by drug action on the ventral brainstem.
• This contrasts with the large, acute adrenaline release seen in typical stress responses.

Conclusions:

• Central administration of various drugs can induce hyperglycemia through a mechanism involving prolonged, low-level adrenaline release.
• This finding suggests an additional physiological role for adrenaline in the day-to-day regulation of blood glucose.
• Dysregulation of this sustained adrenaline release mechanism may contribute to the pathophysiology of non-insulin-dependent diabetes.