Low levels of brain-derived neurotrophic factor and tyrosine kinase receptor B are related to loss of dentate granule cells after prolonged low-protein feeding in the rat.

Protein deprivation leads to neuronal and synaptic loss in the hippocampal formation, and to behavioral changes. We suggested that these effects could result from alterations in the levels of brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB). To investigate this issue, adult rats were submitted to protein deprivation for 6 months and compared with controls. The number of neurons of the dentate gyrus granular layer containing BDNF and TrkB was estimated from immunostained sections and the mRNA levels of BDNF and TrkB evaluated using in situ hybridization. After treatment, there was a loss of BDNF- and TrkB-immunoreactive cells and a reduction of the mRNA levels. Thus, it is likely that the decreased neurotrophic activity in the dentate gyrus of malnourished animals underpins neuronal degeneration and the ensuing behavioral alterations.