Brain and peripheral noradrenergic neuron activity in developing genetically hypertensive rats of the Lyon strain

In order to estimate the alterations in the activity of noradrenergic brain areas and peripheral nerves in relation to genetic hypertension, the concentration and the in-vivo turnover (TO) of norepinephrine (NE) were measured in various brain and peripheral structures of 5 and 22 week-old genetically hypertensive (LH), normotensive (LN) and low blood pressure (LL) male rats of the Lyon strains. LH rats significantly differed from both LN and LL age-matched controls by: i) at 5 weeks, a lowered TO of NE in the anterior hypothalamic region and the median eminence; an elevated TO of NE in the A6 and A7 areas, and in the kidney cortex, and an elevated TO of dopamine in the adrenal medulla, ii) at 22 weeks, a decreased TO of NE in A1 and A6 regions and an increased TO of NE in the thoracic spinal cord. These data suggest that an increased activity of the renal nerves and of the adrenal medulla, possibly originating in central alterations of noradrenergic neurons, could be involved in the development of hypertension in the Lyon strain.