Neuropeptide Y in Rat Sympathetic Neurons Is Altered By Genetic Hypertension and By Age Chandan

We have used immunocytochemistry to quantitate neuronai neuropeptide Y in superior cervical ganglia of a strain of nonnotensive Wistar-Otago rats and a related genetically hypertensive strain over the age range 1-60 weeks. The numbers of neuropeptide Y-immunoreactive cells and total ganglionic cell numbers were both greater in ganglia of young nonnotensive than in those of hypertensive rats. Between 10 and 60 weeks of age, peptide immunoreactivity and total cell numbers both fell in nonnotensive rat ganglia but remained constant in ganglia from hypertensive rats. Densitometric analysis showed that the concentrations of neuropeptide Y were similar in neurons of age-matched individuals of both strains, but during aging there was a substantial decline in neuronai peptide content that was similar in both strains and that was not accompanied by any decline in neuronai immunoreactivity for tyrosine hydroxylase. Our results suggest that there is a developmental abnormality of neuropeptide Y in sympathetic neurons of this strain of genetically hypertensive rat and that, furthermore, the aging process is accompanied by a selective loss of neuronai neuropeptide Y that is independent of blood pressure status. (Hypertension 1990;16:63-71)