Y. Xiong et al., DIFFERENCE IN TOPOLOGY AND NUMBERS OF BAROSENSITIVE CATECHOLAMINERGICAND CHOLINERGIC NEURONS IN THE MEDULLA BETWEEN SHR AND WKY RATS, Journal of the autonomic nervous system, 70(3), 1998, pp. 200-208
We hypothesized that there may be a significant difference in the neur
onal composition of the baroreceptor reflex pathway between normotensi
ve Wistar Kyoto (WKY) and spontaneously hypertensive SHR rats. Using t
he double-immunoreactive (IR) method, the topology and numbers of baro
sensitive neurons that contain glutamate (Glu), glutamic acid decarbox
ylase (GAD), tyrosine hydroxylase (TH), phenylethanolamine N-methyltra
nsferase (PNMT) and choline acetyltransferase (ChAT) were compared bet
ween the two strains. The control rats were sham-operated only for can
nulation of the trachea and femoral artery/vein. The test rats were in
jected with the presser agent phenylephrine to raise blood pressure an
d stimulate arterial baroreceptors. In both the control and test exper
iments, the c-Fos/Glu-, GAD-, TH- and PNMT-IR neurons were found in th
e nucleus tractus solitarii (NTS) and ventrolateral medulla (VLM), whi
le the FosB/ChAT-IR neurons were found in the NTS, dorsal motor nucleu
s of the vagus (DMX) and nucleus ambiguus (AMB). In the control experi
ment, no significant difference in numbers was recognized in any of th
e double-IR neurons between the two strains. In the test experiment, t
he numbers of FosB/ChAT-IR neurons in the NTS, DMX and AMB were signif
icantly smaller in SHR than in WKY. The numbers of c-Fos/TH-IR neurons
in the caudal VLM were significantly larger in SHR than in WKY. These
results suggest that a smaller number of barosensitive cholinergic ne
urons in the DMX and AMB in SHR causes the weaker baroreceptor-cardiac
vagal reflex in SHR, and that a larger number of barosensitive catech
olaminergic neurons in the caudal VLM in SHR are involved in the stron
ger baroreceptor-vasopressin reflex in SHR. (C) 1998 Elsevier Science
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