Dehydration-induced modulation of kappa-opioid inhibition of vasopressin neurone activity
| Autor: | Scott, V., Bishop, V. R., Leng, G., Brown, C. H. |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
RNA
Messenger/genetics Oxytocin/physiology Physiology Cholecystokinin/pharmacology Enkephalins/biosynthesis Enkephalins/genetics Action Potentials/drug effects Vasopressins/physiology Rats Sprague-Dawley Dehydration/physiopathology Animals Narcotic Antagonists/pharmacology In Situ Hybridization Naltrexone/pharmacology Protein Precursors/genetics Receptors Opioid kappa/physiology RNA Messenger/biosynthesis Oxytocin/pharmacology Receptors Opioid kappa/antagonists & inhibitors Immunohistochemistry Neurons/drug effects Hypernatremia/physiopathology Rats Electrophysiology Naltrexone/analogs & derivatives Hyponatremia/physiopathology Female Protein Precursors/biosynthesis Neurons/physiology |
| Zdroj: | Scott, V, Bishop, V R, Leng, G & Brown, C H 2009, ' Dehydration-induced modulation of kappa-opioid inhibition of vasopressin neurone activity ', Journal of Physiology, vol. 587, no. 23, pp. 5679-5689 . https://doi.org/10.1113/jphysiol.2009.180232 |
| DOI: | 10.1113/jphysiol.2009.180232 |
| Popis: | Dehydration increases vasopressin (antidiuretic hormone) secretion from the posterior pituitary gland to reduce water loss in the urine. Vasopressin secretion is determined by action potential firing in vasopressin neurones, which can exhibit continuous, phasic (alternating periods of activity and silence), or irregular activity. Autocrine kappa-opioid inhibition contributes to the generation of activity patterning of vasopressin neurones under basal conditions and so we used in vivo extracellular single unit recording to test the hypothesis that changes in autocrine kappa-opioid inhibition drive changes in activity patterning of vasopressin neurones during dehydration. Dehydration increased the firing rate of rat vasopressin neurones displaying continuous activity (from 7.1 +/- 0.5 to 9.0 +/- 0.6 spikes s-1) and phasic activity (from 4.2 +/- 0.7 to 7.8 +/- 0.9 spikes s-1), but not those displaying irregular activity. The dehydration-induced increase in phasic activity was via an increase in intraburst firing rate. The selective kappa-opioid receptor antagonist nor-binaltorphimine increased the firing rate of phasic neurones in non-dehydrated rats (from 3.4 +/- 0.8 to 5.3 +/- 0.6 spikes s-1) and dehydrated rats (from 6.4 +/- 0.5 to 9.1 +/- 1.2 spikes s-1), indicating that kappa-opioid feedback inhibition of phasic bursts is maintained during dehydration. In a separate series of experiments, prodynorphin mRNA expression was increased in vasopressin neurones of hyperosmotic rats, compared to hypo-osmotic rats. Hence, it appears that dynorphin expression in vasopressin neurones undergoes dynamic changes in proportion to the required secretion of vasopressin so that, even under stimulated conditions, autocrine feedback inhibition of vasopressin neurones prevents over-excitation. |
| Databáze: | OpenAIRE |
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