Functional regulation of tactile sense by brain-derived neurotrophic factor in adult rats during acute inflammation

Nerve growth factor is present in skin in limiting amounts and is known to regulate the plasticity and the sensitivity of nociceptive neurons. Recently, knock-out mouse studies showed that neurotrophin-3 and brain-derived neurotrophic factor are required for the postnatal survival and functional maturation, respectively, of tactile sensory neurons. However, the roles of neurotrophin-3 and brain-derived neurotrophic factor in adult sensory neurons have not been clarified. Here, we report an unexpected and marked acute loss of tactile sense in the rat hind paw after adjuvant-induced inflammation. This loss was shown to be closely correlated with decreases in the expression of brain-derived neurotrophic factor, and to a lesser extent of neurotrophin-3 in the inflamed skin. Administration of brain-derived neurotrophic factor, but not neurotrophin-3, after inflammation accelerated the recovery of tactile sense.These results suggested a role of brain-derived neurotrophic factor in the physiological regulation of tactile sense in adulthood.