Adventures in neural plasticity, aging, and neurodegenerative disorders aboard the CWC beagle

The histopathological evaluation of small fiber neuropathy in patients with vitamin B12 deficiency

Small fiber neuropathy (SFN), due to loss of A-delta and unmyelinated C fibers, is a cause of neuropathic pain. Although the patients with vitamin B12 deficiency are included in SFN studies in the literature, there is no histopathological study investigating the small fiber loss solely in patients with vitamin B12 deficiency. In this pilot study, we aim to demonstrate the intraepidermal nerve fiber density (IENFD) in skin punch biopsy of patients with vitamin B12 deficiency. Ten patients with vitamin B12 deficiency suffering from neuropathic pain and as control group ten patients with vitamin B12 deficiency without neuropathic pain were included. Neurological examination, electrophysiological evaluation, and DN4 questionnaire were performed. Subsequently, skin punch biopsy 10 cm above the lateral malleolus was done. The biopsy samples were stained with PGP9.5 antibody, and IENFD was determined. IENFD was low in two groups compared to their age normative values. The median of IENFD was 3.345 (1.12-5.32) in patients with neuropathic pain and 6. 20 (4.6-9.8) in controls (p < 0.001). Our pilot study showed that vitamin B12 deficiency causes symptomatic as well as asymptomatic small fiber loss like diabetes mellitus.

Differences in doublecortin immunoreactivity and protein levels in the hippocampal dentate gyrus between adult and aged dogs

Doublecortin (DCX), a microtubule-associated protein, specifically expresses in neuronal precursors. This protein has been used as a marker for neuronal precursors and neurogenesis. In the present study, we observed differences in DCX immunoreactivity and its protein levels in the hippocampal dentate gyrus between adult and aged dogs. In the adult dog, DCX immunoreactive cells with well-stained processes were detected in the subgranular zone of the dentate gyrus. Numbers of DCX immunoreactive cells in the dentate gyrus of the aged dog were significantly decreased compared to those in the adult dog. DCX immunoreactive cells in both adult and aged dog did not show NeuN (a marker for mature neurons) immunoreactivity. NeuN immunoreactivity in the aged dog was poor compared to that in the adult dog. DCX protein level in the aged dentate gyrus was decreased by 80% compared to that in the adult dog. These results suggest that the reduction of DCX in the aged hippocampal dentate gyrus may be involved in some neural deficits related to the hippocampus.