Brain–derived neurotrophic factor modulates the dopaminergic network in the axotomized rat retina

Abstract

Abstract: : Purpose: To evaluate whether BDNF can influence the network of dopaminergic amacrine cell at the axotomized rat retina. Methods: Optic nerve transection (ONT) was performed at 5 mm posterior to the optic nerve head. Human recombinant BDNF (5 µg in 5 µl sterile saline; Regeneron Pharmaceuticals, Tarrytown, NY, USA) was injected into the vitreal chamber of each eye immediately after the optic nerve transection, using a Hamilton syringe with a 30–gauge needle. Vibratome sections were double labeled using antisera tyrosine hydroxylase (TH) and parbalbumin. Results: The type I cell had a larger–sized soma located in the INL with processes ramifying mainly in stratum 1 of the IPL and weak processes in stratum 3 and also occasional processes in the outer plexiform layer (OPL). The type II cell had a smaller–sized soma and processes branching in stratum 3 of the IPL. The type I amacrine cell varicosities in stratum 1 of the IPL forming ring–like structures have been disrupted at 7 and 14 days after ONT. The type II amacrine cell processes ramifying in stratum 3 of the IPL disappeared at 7 and 14 days after ONT. Double–labeling experiment using antisera against TH and parvalbumin, AII amacrine cell marker, demonstrated that AII amacrine cell body that receive multiple synapses from dopaminergic amacrine cells at stratum 1 of the IPL has been disrupted. After BDNF treatment, strong TH immunoreactive varicosities in stratum 1 of the IPL forming ring like structures and more processes in stratum 3 of type 1 cell and processes of type 2 cell ramifying in stratum 3 have been observed at 7 and 14 days after ONT. Conclusions: Our data suggest that BDNF has a regulatory effect on the expression of TH in the dopaminergic cells of the rat retina.

Keywords: amacrine cells • dopamine • retina