Lesions of the dorsal noradrenergic bundle augment the renin response to blood loss but do not alter hypothalamic Fos expression

Brain Research Bulletin
R L Jaworski, M L Blair

Abstract

The goal of this study was to determine if the dorsal noradrenergic bundle (DNAB) plays an essential role in mediating increased plasma renin activity (PRA) and hypothalamic activation, as indicated by increased Fos expression, in response to a small volume blood loss in unanesthetized animals. Male Sprague-Dawley rats were prepared with bilateral 6-hydroxydopamine or sham lesions of the dorsal noradrenergic bundle. In both groups of animals, blood pressure decreased by only 10-15 mmHg following hemorrhage (10 ml/kg over 15 min). Plasma renin activity increased similarly in both groups after 5 ml/kg blood loss, but showed a significantly greater increase after 10 ml/kg blood loss in animals with 6-hydroxydopamine lesions than in those with sham lesions (increase of 13.8 +/- 2.0 ng/ml/h versus 8.4 +/- 1.2 ng/ml/h; P < 0.025). There were numerous Fos-immunoreactive cell nuclei in the supraoptic nucleus (SON) and parvicellular paraventricular hypothalamic nucleus (PVN) of hemorrhaged animals. The number of Fos-positive neurons did not differ between groups, indicating that the dorsal noradrenergic bundle does not convey the primary drive for supraoptic and paraventricular nucleus activation during blood loss. However, one or more ...Continue Reading

References

Aug 1, 1988·The Journal of Comparative Neurology·E T Cunningham, P E Sawchenko
Jan 1, 1971·Acta Physiologica Scandinavica. Supplementum·U Ungerstedt
Feb 1, 1996·Clinical and Experimental Pharmacology & Physiology·L P Renaud
Feb 1, 1996·Clinical and Experimental Pharmacology & Physiology·M L BlairJ A Olschowka
Jan 12, 1999·Frontiers in Neuroendocrinology·L D Van de Kar, M L Blair

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