Naunyn Schmiedebergs Arch Pharmacol. 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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