Thursday, September 19, 2013

Differential amino acid transmission in the locus coeruleus of Wistar Kyoto and spontaneously hypertensive rats.

 2004 Nov;370(5):381-7. Epub 2004 Oct 23.

Source

Department of Pharmacology and Toxicology, University of Innsbruck, Austria

Previously it was known that Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) differ in their emotional behaviour. It is also known that both groups differ in their blood pressure. In this study the authors wanted to test if there is any difference in the release rate of GABA and glutamate in the locus coeruleus. Locus coeruleus, is a nucleus in the brainstem that is known to be involved in the physiological responses to stress, it is activated by stress, and will respond by increasing norepinephrine secretion and it mediates many sympathetic effects during stress. WKY rats show normal blood pressure and enhanced anxiety related behaviour when compared to SHR rats with high blood pressure and low anxiety. When experimental hypertension was induced with noradrenaline GABA release went up in WKY rats but no changes were seen in SHR rats. Glutamate release was not affected under the above condition. Upon administration of sodium nitroprusside the blood pressure went down in both groups but the aminoacid release was not affected. Mild stress was induced by tail pinching which led to an increase in the release of glutamate and GABA in locus coeruleus of both groups. In conclusion, SHR and WKY rats differ in GABAnergic neurotransmission, in response blood pressure challenges, but not to mild stressors. A disturbed mechanism counteracting high blood pressure may be responsible for the observed lack of GABA response to blood pressure elevation in SHR and that may possibly contribute to hypertension in this strain.

-Madhan

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