The levels of neurotrophins and their receptor mRNAs were measured in rat sciatic nerve, after 6 or 12 weeks of streptozotocin-induced diabetes. Expression of neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) was decreased by 50 and 29%, respectively, compared with age-matched controls after 12 weeks of diabetes. Expression of brain-derived neurotrophic factor (BDNF) was not detected. In addition, diabetes induced a reduction in the expression levels of the neurotrophin receptors: trkB mRNA decreased by 50% after 6 weeks of diabetes, but returned to control levels after 12 weeks; meanwhile the trkC and p75LNGFR transcripts were reduced by 20% of control at both times studied. trkA expression was below detection limits. Thus, these data suggest that a reduction in neurotrophin and neurotrophin receptors could contribute to the development and maintenance of diabetic neuropathy.
Animals Diabetes Mellitus, Experimental