Lack of sympathetic and cholinergic influences on cerebral vasodilation caused by sciatic nerve stimulation in the rat.
We studied the influences of sympathetic and cholinergic mechanisms on pial arteriolar responses during cortical activation in the rat. Adult male Sprague-Dawley rats were anesthetized with alpha-chloralose and urethane and mechanically ventilated. Pial arterioles on the somatosensory cortex were visualized on a video monitor through a closed cranial window. Changes in arteriolar diameter induced by sciatic nerve stimulation (0.2 V, 5 Hz, 5 ms, for 20 s) were measured before and after (a) ipsilateral superior cervical ganglionectomy (n = 5), (b) intravenous (0.5 mg/kg) administration and topical (10(-5) M) application of atropine (n = 5), and (c) lesion of the nucleus basalis magnocellularis (the major source of intracerebral acetylcholine neurons, n = 7). Unilateral nucleus basalis magnocellularis lesions were performed stereotactically by injection of ibotenic acid (25 nmol/microliter). Sensory cortex cholinergic denervation was confirmed histologically. These treatments had no significant effect on arteriolar responses to sciatic nerve stimulation. Thus, the present results suggest that neither sympathetic nor cholinergic mechanisms play a significant role in somatosensory evoked cerebral vasodilation.
Ibayashi
S
S
Department of Neurological Surgery, University of Washington School of Medicine, Seattle 98104.
Ngai
A C
AC
Howard
M A
MA
Meno
J R
JR
Mayberg
M R
MR
Winn
H R
HR
D000818:Animals; D001160:Arterioles / Q000294:innervation / Q000502:physiology; D001285:Atropine / Q000494:pharmacology; D001921:Brain / Q000098:blood supply*; D002794:Choline / Q000502:physiology*; D004558:Electric Stimulation; D005728:Ganglia, Sympathetic / Q000502:physiology / Q000601:surgery; D015171:Ganglionectomy; D007051:Ibotenic Acid / Q000494:pharmacology; D008297:Male; D009847:Olivary Nucleus / Q000187:drug effects / Q000502:physiology; D010841:Pia Mater / Q000098:blood supply; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D014664:Vasodilation
D007051:Ibotenic Acid; D001285:Atropine; D002794:Choline