Hypertension in Prenatally Undernourished Young-Adult Rats Is Maintained by Tonic Reciprocal Paraventricular–Coerulear Excitatory Interactions |
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Authors: | Bernardita Cayupe,Carlos Morgan,Gustavo Puentes,Luis Valladares,Hé ctor Burgos,Amparo Castillo,Alejandro Herná ndez,Luis Constandil,Miguel Rí os,Patricio Sá ez-Briones,Rafael Barra |
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Abstract: | Prenatally malnourished rats develop hypertension in adulthood, in part through increased α1-adrenoceptor-mediated outflow from the paraventricular nucleus (PVN) to the sympathetic system. We studied whether both α1-adrenoceptor-mediated noradrenergic excitatory pathways from the locus coeruleus (LC) to the PVN and their reciprocal excitatory CRFergic connections contribute to prenatal undernutrition-induced hypertension. For that purpose, we microinjected either α1-adrenoceptor or CRH receptor agonists and/or antagonists in the PVN or the LC, respectively. We also determined the α1-adrenoceptor density in whole hypothalamus and the expression levels of α1A-adrenoceptor mRNA in the PVN. The results showed that: (i) agonists microinjection increased systolic blood pressure and heart rate in normotensive eutrophic rats, but not in prenatally malnourished subjects; (ii) antagonists microinjection reduced hypertension and tachycardia in undernourished rats, but not in eutrophic controls; (iii) in undernourished animals, antagonist administration to one nuclei allowed the agonists recover full efficacy in the complementary nucleus, inducing hypertension and tachycardia; (iv) early undernutrition did not modify the number of α1-adrenoceptor binding sites in hypothalamus, but reduced the number of cells expressing α1A-adrenoceptor mRNA in the PVN. These results support the hypothesis that systolic pressure and heart rate are increased by tonic reciprocal paraventricular–coerulear excitatory interactions in prenatally undernourished young-adult rats. |
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Keywords: | hypertension, prenatal undernutrition, paraventricular nucleus, locus coeruleus, noradrenaline, corticotropin-releasing factor, α 1-adrenoceptor, rat |
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