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Mechanisms involved in the pressor response to noradrenaline microinjection into the supraoptic nucleus of unanesthetized rats.
- Source :
-
Autonomic neuroscience : basic & clinical [Auton Neurosci] 2009 Jan 28; Vol. 145 (1-2), pp. 63-70. Date of Electronic Publication: 2008 Dec 06. - Publication Year :
- 2009
-
Abstract
- We report on the cardiovascular effects of noradrenaline (NA) microinjection into the hypothalamic supraoptic nucleus (SON) as well as the central and peripheral mechanisms involved in their mediation. Microinjections of NA 1, 3, 10, 30 or 45 nmol/100 nL into the SON caused dose-related pressor and bradycardiac response in unanesthetized rats. The response to NA 10 nmol was blocked by SON pretreatment with 15 nmol of the alpha(2)-adrenoceptor antagonist RX821002 and not affected by pretreatment with equimolar dose of the selective alpha(1)-adrenoceptor antagonist WB4101, suggesting that local alpha(2)-adrenoceptors mediate these responses. Pretreatment of the SON with the nonselective beta-adrenoceptor antagonist propranolol 15 nmol did not affect the pressor response to NA microinjection of into the SON. Moreover, the microinjection of the 100 nmol of the selective alpha(1)-adrenoceptor agonist methoxamine (MET) into the SON did not cause cardiovascular response while the microinjection of the selective alpha(2)-adrenoceptor agonists BHT920 (BHT, 100 nmol) or clonidine (CLO, 5 nmol) caused pressor and bradycardiac responses, similar to that observed after the microinjection of NA. The pressor response to NA was potentiated by intravenous pretreatment with the ganglion blocker pentolinium and was blocked by intravenous pretreatment with the V(1)-vasopressin receptor antagonist dTyr(CH2)5(Me)AVP, suggesting an involvement of circulating vasopressin in this response. In conclusion, our results suggest that pressor responses caused by microinjections of NA into the SON involve activation of local alpha(2)-adrenoceptor receptors and are mediated by vasopressin release into circulation.
- Subjects :
- Animals
Blood Pressure drug effects
Blood Pressure physiology
Dose-Response Relationship, Drug
Male
Pressoreceptors physiology
Rats
Rats, Wistar
Supraoptic Nucleus physiology
Wakefulness physiology
Microinjections methods
Norepinephrine administration & dosage
Pressoreceptors drug effects
Supraoptic Nucleus drug effects
Wakefulness drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 1872-7484
- Volume :
- 145
- Issue :
- 1-2
- Database :
- MEDLINE
- Journal :
- Autonomic neuroscience : basic & clinical
- Publication Type :
- Academic Journal
- Accession number :
- 19059010
- Full Text :
- https://doi.org/10.1016/j.autneu.2008.11.005