NEONATAL ANTI-NGF TREATMENT REDUCES THE A-DELTA-FIBER AND C-FIBER EVOKED VASODILATOR RESPONSES IN RAT SKIN - EVIDENCE THAT NOCICEPTOR AFFERENTS MEDIATE ANTIDROMIC VASODILATATION

Here we have examined this phenomenon in adult rats treated neonatally with antisera to nerve growth factor between postnatal days 2 and 14. This treatment forces many Adelta nociceptor afferents to take on the phenotype of low-threshold D-hair afferents (Lewin et al, J. Neurosci., 12, 1896-1905, 1992). In animals treated this way we found a parallel decrease in the ability of Adelta-fibres to increase skin blood flow. The increase in blood flow evoked by C-fibre stimulation was also reduced, but no change was seen in the ability of C-fibres to elicit neurogenic extravasation in skin. These data may be taken as evidence that in rats, amongst the cutaneous Adelta-fibres, nociceptor but not D-hair afferents are capable of producing blood flow changes in the skin.