LOCUS COERULEUS NORADRENERGIC INNERVATION OF THE AMYGDALA FACILITATES ALERTING-INDUCED CONSTRICTION OF THE RAT TAIL ARTERY.

Mazher Mohammed, Keerthi Kulasekara, Youichirou Ootsuka, William Blessing

    Research output: Contribution to journalArticlepeer-review

    7 Citations (Scopus)

    Abstract

    The amygdala, innervated by the noradrenergic locus coeruleus, processes salient environmental events. α2-adrenoceptor-stimulating drugs (clonidine-like agents) suppress the behavioral and physiological components of the response to salient events. Activation of sympathetic outflow to the cutaneous vascular bed is part of the physiological response to salience-mediated activation of the amygdala. We have determined whether acute systemic and intra-amygdala administration of clonidine, and chronic immunotoxin-mediated destruction of the noradrenergic innervation of the amygdala, impairs salience-related vasoconstrictor episodes in the tail artery of conscious freely moving Sprague-Dawley rats. After acute intraperitoneal injection of clonidine (10, 50, and 100 μg/kg), there was a dose-related decrease in the reduction in tail blood flow elicited by alerting stimuli, an effect prevented by prior administration of the α2-adrenergic blocking drug idazoxan (1 mg/kg ip or 75 nmol bilateral intra-amygdala). A dose-related decrease in alerting-induced tail artery vasoconstriction was also observed after bilateral intra-amygdala injection of clonidine (5, 10, and 20 nmol in 200 nl), an effect substantially prevented by prior bilateral intra-amygdala injection of idazoxan. Intra-amygdala injection of idazoxan by itself did not alter tail artery vasoconstriction elicited by alerting stimuli. Intra-amygdala injection of saporin coupled to antibodies to dopamine-β-hydroxylase (immunotoxin) destroyed the noradrenergic innervation of the amygdala and the parent noradrenergic neurons in the locus coeruleus. The reduction in tail blood flow elicited by standardized alerting stimuli was substantially reduced in immunotoxin-treated rats. Thus, inhibiting the release of noradrenaline within the amygdala reduces activation of the sympathetic outflow to the vascular beds elicited by salient events.

    Original languageEnglish
    Pages (from-to)R1109-R1119
    Number of pages11
    JournalAmerican Journal of Physiology-Regulatory Integrative and Comparative Physiology
    Volume310
    Issue number11
    DOIs
    Publication statusPublished - Jun 2016

    Keywords

    • Clonidine
    • Cutaneous blood flow
    • Dopamine-β-hydroxylase
    • Immunotoxin
    • α -adrenergic receptor

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