Comparison of neuropeptide Y immunoreactivity in hypothalamic and brainstem nuclei of young and mature spontaneously hypertensive and normotensive Wistar-Kyoto rats

The concentration of neuropeptide Y immunoreactivity (NPY-ir) was measured in 8 hypothalamic and 5 brainstem nuclei of 6- and 14-week-old spontaneously hypertensive (SH) and Wistar-Kyoto (WKY) rats. Strain differences were observed in 3 hypothalamic nuclei and age-dependent changes occurred in 3 hypothalamic and 2 brainstem nuclei. In both the ventromedial hypothalamic nucleus and locus coeruleus the observed change in NPY-ir with age in SH rats was significantly different to the change observed in the WKY. These strain- and age-related differences in NPY-ir may be of relevance in the development of hypertension in the SH rat.