Hypoglycemia-induced noradrenergic activation in the VMH is a result of decreased ambient glucose
| Autor: | Martin G. de Vries, Marcus A. Lawson, J. Lee Beverly |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Male
medicine.medical_specialty Microdialysis Physiology medicine.medical_treatment Biology Hypoglycemia Rats Sprague-Dawley Norepinephrine Physiology (medical) Internal medicine Extracellular fluid medicine Animals Pancreatic hormone Neurons Neurotransmitter Agents Insulin medicine.disease Adaptation Physiological Rats Glucose Endocrinology Ventromedial Hypothalamic Nucleus Hypothalamus Catecholamine medicine.drug |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 289:R977-R981 |
| ISSN: | 1522-1490 0363-6119 |
| Popis: | During insulin-induced hypoglycemia, there is an increase in extracellular norepinephrine (NE) in the ventromedial hypothalamus (VMH). This brain area is known to play an important role in integrated hormonal and behavioral responses to systemic hypoglycemia. Selective glucoprivation restricted to the VMH is both necessary and sufficient to initiate secretion of counterregulatory hormones. The present study was designed to investigate whether increased release of NE in the VMH depends on detection of glucoprivation localized in this area. In awake, chronically catheterized male Sprague-Dawley rats, extracellular NE in the VMH was monitored using 1-mm microdialysis probes perfused with Krebs Ringer buffer (KRB) or KRB + 100 mM d-glucose (d-Glc). During insulin-induced hypoglycemia (glycemic nadir ∼2.4 mM) extracellular NE was increased to >160% of baseline ( P < 0.01) only in the KRB + insulin group. There was no increase in NE from baseline when glucose was added to the perfusate to maintain euglycemia at the periprobe environment. The sympathoadrenal response to hypoglycemia, present in the KRB + insulin group, was attenuated in the d-Glc + insulin group. The present results confirm that noradrenergic activation in the VMH during systemic hypoglycemia depends on detection of glucoprivation locally in this area. These data provide additional support for the importance of increased noradrenergic activity in the VMH in the counterregulatory hormonal responses to hypoglycemia. |
| Databáze: | OpenAIRE |
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