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Updated: Jul 13, 2026

Simultaneous Detection of c-Fos Activation from Mesolimbic and Mesocortical Dopamine Reward Sites Following Naive Sugar and Fat Ingestion in Rats
Published on: August 24, 2016
High fructose diet increases anterior hypothalamic alpha 2-adrenoceptors responsiveness
Marcos A Mayer1, Christian Höcht, Javier A Opezzo
1Department of Macro and Microscopic Anatomy, Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Junin 956, C1113AAD Buenos Aires, Argentina. marcos.mayer@gmail.com
Abstract:
Activation of alpha(2)-adrenoceptors in the anterior hypothalamic area (AHA) decreases sympathetic nervous system activity and blood pressure. The aim of the present study was to evaluate activity of pre- and postsynaptic alpha(2)-adrenoceptors in the AHA of fructose hypertensive rats (F), an animal model of insulin resistance and hypertension. The AHA of Control (C) and F anaesthetized rats was perfused with Ringer solution in the absence or presence of clonidine (100 or 300 microg ml(-1)) using reverse microdialysis. Clonidine effects on mean arterial pressure (MAP) and heart rate (HR), and on hypothalamic noradrenaline levels were measured along perfusion time. Noradrenaline extracellular levels in the AHA were significantly diminished in F hypertensive rats compared to C animals. The depressor effect of intrahypothalamic perfusion of clonidine on MAP was enhanced in F rats compared with C animals. Intrahypothalamic perfusion of clonidine reduced HR only in F rats. The effect of clonidine on noradrenaline hypothalamic extracellular levels was enhanced in F rats. These results suggest, in our experimental conditions, the existence of an increased responsiveness of pre- and postsynaptic alpha(2)-adrenoceptors in the AHA of F hypertensive rats. This fact could be a consequence of a compensatory supersensitivity of alpha-adrenoceptors due to a decrease in noradrenaline release from nerve terminals located in the AHA.
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