Increased number of PNMT-immunofluorescent nerve cell bodies in the medulla oblongata of stroke-prone hypertensive rats.

An antiserum to bovine adrenal PNMT was used to identify PNMT-containing nerve cell bodies in the medulla oblongata of 4-week-old normotensive Wistar-Kyoto rats and stroke-prone spontaneously hypertensive rats. The regional distribution of PNMT cells and the total number of PNMT cell profiles in tranverse sections of the medulla were examined in each of the two strains. While there was no significant difference in the pattern of distribution of the cells, both the number of PNMT cell profiles per section and the total number seen in all sections of the medulla were significantly higher in the hypertensive rats. The increase in counts of PNMT cell profiles in the medulla suggests that there is a genetic difference in the number of central adrenaline neurons in these hypertensive rats. This is supported by the finding of similar increases of PNMT enzyme activity in the medulla of both stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats compared with Wistar-Kyoto rats.