NORADRENERGIC AND NEUROPEPTIDE Y-IMMUNOREACTIVE NERVES IN THE PANCREATIC-ISLETS OF SPONTANEOUSLY HYPERTENSIVE RATS

Innervation by noradrenergic (NA) and neuropeptide Y-immunoreactive (N PY-IR) nerves to the pancreatic islets and the arteries supplying the islets was studied by immunocytochemistry in 6- and 20-week-old sponta neously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WK Y). Since both the NA and NPY-IR nerves follow the intra- and interlob ular small arteries and innervate the islets, we examined mainly the i nnervation of intra- and interlobular small arteries by these nerves. The NA nerve density of the intralobular small arteries supplying the islets was significantly more extensive in 6-week-old SHR than in age- matched WKY (7.11 +/- 1.78 vs. 4.04 +/- 0.71 . 10(-2) mum/mum2, p<0.00 1), and the NPY-IR nerve density of the intralobular small arteries wa s significantly more extensive in SHR than in WKY at 6 weeks of age (7 .68 +/- 2.28 vs. 5.69 +/- 0.91.10(-2) mum/mum2, P<0.05). The interlobu lar small arteries branching off the intralobular small arteries in SH R were also more innervated by NA (P<0.05) and NPY-IR nerves (P<0.001) than by those in WKY at 6 weeks of age. At 20 weeks of age, the NA an d NPY-IR nerve densities of the intra- and interlobular small arteries were higher in SHR than in WKY, and showed an increase with age in bo th strains. In addition, the islet innervation by these nerves in cros s-section appeared denser in SHR than in WKY. The islet innervation by both the NA and the NPY-IR nerves is considered denser in SHR than in WKY because of the rich supply by both nerves in the intra- and inter lobular small arteries.