Nitric oxide and the cerebral-blood-flow response to somatosensory activation following deafferentation

Abstract 

The single-vibrissa stimulation model in the rat was utilized to study the microvascular coupling between functional activation and local cerebral blood flow (LCBF) in both normal cortex and in cortex that had been peripherally deafferented. In addition, the role of chronic nitric oxide synthase (NOS) inhibition on the LCBF response to vibrissa stimulation was examined. One-day-old rats underwent deafferentation of all vibrissae on one side of the face, sparing C3, and received daily administration of either saline or N^ω-nitro-l-arginine (l-NA). After seven weeks of treatment, LCBF was measured autoradiographically in conscious rats with [¹⁴C]N-isopropyl-p-iodoamphetamine while C3 was stimulated bilaterally. Stimulation produced a greater increase in LCBF in the deafferented cortex of both the saline (30.4%) and l-NA treated (25.7%) animals than in the intact cortex (19.9% and 16%, respectively). The area of activation of LCBF (0.176 mm²) was comparable to the area metabolically activated (0.149 mm²), and the increase in area of LCBF activation following deafferentation (169%) was smaller than the increase in area that was metabolically activated (287%). Chronic inhibition of NOS did not alter the spatial extent of the blood-flow response.