TY - JOUR
T1 - Participation of adrenergic and noradrenergic neurones in central connections of arterial baroreceptor reflexes in the rat
AU - Chalmers, J. P.
AU - Petty, M. A.
AU - Reid, J. L.
PY - 1979/10/1
Y1 - 1979/10/1
N2 - The authors examined activities of tyrosine hydroxylase (TH) and phenylethanolamine-N-methyl transferase (PNMT) and concentrations of norepinephrine (NE) in seven brain regions and the spinal cord of Wistar rats with elevated blood pressures 1 week and 4 weeks after denervation of carotid and aortic baroreceptors, and compared them to values in sham-operated control rats TH activity was increased in the solitary tract nucleus (to 188% of control), parahypoglossal nucleus (to 254%), locus ceruleus (to 191%), and posterior hypothalamus (to 225%) at 1 week but not at 4 weeks after denervation. Similarly, NE concentrations were significantly altered in a number of brain regions at 1 week but not at 4 weeks after denervation. The only change in NE concentration at 4 weeks was in spinal cord where the level was reduced to 80% of control in the denervated rats. In contrast, the only change in PNMT activity 1 week after denervation was in posterior hypothalamus (to 59% of control), whereas at 4 weeks there was an increase in the spinal cord (to 159%) and a decrease in both the anterior and posterior hypothalamus (to 59% and 64% of control, respectively). The experiments suggest that increased activity of noradrenergic neurones in the brain may play a significant role in initiating the increase in pressure produce by baroreceptor denervation, whereas decreased activity of hypothalamic adrenergic neurones may be more important in maintaining the raised pressure. An increase in the activity of both adrenergic and noradrenergic nerves in the spinal cord, however, could contribute to maintaining the increase in blood pressure 4 weeks after denervation.
AB - The authors examined activities of tyrosine hydroxylase (TH) and phenylethanolamine-N-methyl transferase (PNMT) and concentrations of norepinephrine (NE) in seven brain regions and the spinal cord of Wistar rats with elevated blood pressures 1 week and 4 weeks after denervation of carotid and aortic baroreceptors, and compared them to values in sham-operated control rats TH activity was increased in the solitary tract nucleus (to 188% of control), parahypoglossal nucleus (to 254%), locus ceruleus (to 191%), and posterior hypothalamus (to 225%) at 1 week but not at 4 weeks after denervation. Similarly, NE concentrations were significantly altered in a number of brain regions at 1 week but not at 4 weeks after denervation. The only change in NE concentration at 4 weeks was in spinal cord where the level was reduced to 80% of control in the denervated rats. In contrast, the only change in PNMT activity 1 week after denervation was in posterior hypothalamus (to 59% of control), whereas at 4 weeks there was an increase in the spinal cord (to 159%) and a decrease in both the anterior and posterior hypothalamus (to 59% and 64% of control, respectively). The experiments suggest that increased activity of noradrenergic neurones in the brain may play a significant role in initiating the increase in pressure produce by baroreceptor denervation, whereas decreased activity of hypothalamic adrenergic neurones may be more important in maintaining the raised pressure. An increase in the activity of both adrenergic and noradrenergic nerves in the spinal cord, however, could contribute to maintaining the increase in blood pressure 4 weeks after denervation.
UR - http://www.scopus.com/inward/record.url?scp=0018700651&partnerID=8YFLogxK
U2 - 10.1161/01.RES.45.4.516
DO - 10.1161/01.RES.45.4.516
M3 - Article
C2 - 38913
AN - SCOPUS:0018700651
VL - 45
SP - 516
EP - 522
JO - Circulation Research
JF - Circulation Research
SN - 0009-7330
IS - 4
ER -