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Reduced Cortical Vasodilatory Response to Stimulation of the Nucleus Basalis of Meynert in the Aged Rat and Evidence for a Control of the Cerebral Circulation
Author(s) -
LACOMBE PIERRE,
SERCOMBE RICHARD,
VAUCHER ELVIRE,
SEYLAZ JACQUES
Publication year - 1997
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1997.tb48494.x
Subject(s) - nucleus basalis , microcirculation , stimulation , cholinergic , cerebral cortex , cerebral blood flow , vasodilation , medicine , endocrinology , blood flow , hypercapnia , physostigmine , cerebral circulation , neuroscience , cholinergic neuron , biology , respiratory system
In earlier studies we showed that electrical stimulation of the rat nucleus basalis of Meynert (NBM) induces large increases in cerebral blood flow, mainly through cholinergic mechanisms. We then investigated the effect of aging on this influence by measuring cortical blood flow (CoBF) and tissue gas partial pressures (PtO2, PtCO2) in the conscious young adult and aged rat. NBM stimulation increased frontal (+101%) and parietal (+29%) CoBF in young rats. The effects were halved in aged rats. Moreover, PtO2 was significantly increased in young but not in aged rats. By contrast, the corticovascular reactivity to hypercapnia did not differ between young and aged rats, nor did the potentiating vasodilator effect of physostigmine. In combined autoradiographic measurements of cerebral blood flow and cerebral glucose utilization, we recently found that the cortical circulatory response to NBM stimulation was not accompanied by significant metabolic change. Thus, the blood flow changes observed in the cortex cannot be ascribed to increased metabolic activity. The distribution of this uncoupling coincides with that of cholinergic NBM projections directly impinging on cortical microvessels. These data support the cortical microcirculation and suggest the possible involvement of NBM dysfunction in the pathology of cortical microcirculation.