Volume 5 Issue 2, December 1995: 209-220
ORIGINAL ARTICLES
Noradrenaline as a putative neurotransmitter mediating hypotension-induced Fos-like immunoreactivity in the supraoptic nucleus of the rat.
SHEN EH, XIA SUN
Shanghai Brain Research Institute, Chinese Academy of Sciences, Shanghai 200031, China.
Correspondence: SHEN EH
Hemorrhage or hypotension induces extensive Fos-like immunoreactivity in the magnocellular neurosecretory cells in the supraoptic nucleus of the hypothalamus in rat, especially in the vasopressin neurons. The present study was to explore the neurotransmitter mediating this effect. Microinfusion of the alpha-adrenergic blocker into the supraoptic nucleus reduced the hypotension-induced Fos, whereas beta-antagnist did not affect it significantly. Alpha1-and alpha2-antagonist, prazosin and yohimbine, both reduced the Fos-positive cell counts. However, the effective dosage of yohimbine was much larger. Alpha1-agoist, methoxamine, induced abundant Fos-like immunoreactivity in the vasopressin cells in this nucleus, while beta-and alpha2-agonist did not elicit such effect. Administration of the noradrenergic re-uptake inhibitor, desipramine, to this nucleus to locally accumulate the spontaneously released noradrenaline from the nerve terminal also induced Fos expression, mostly in the vasopressin cells.
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