Abstract
Abstract: :
Purpose: Our previous physiological and pharmacological studies have shown that spontaneous retinal waves occur in the ventricular zone (VZ) of the developing mammalian retina, and they are dependent on cholinergic neurotransmission. However, it is still unclear as to the origin of this neurotransmission within the retinal layers. Present study was designed to ascertain the location of cholinergic markers in the retina by labeling the expression of ChAT and M1 receptors using immunohistochemical methods. Methods: Eyes from late embryonic and early postnatal rabbits and mice were fixed with 4% paraformaldehyde and sectioned at a thickness of 10 µm on a –20° C cryostat, and stored at –70° C until staining. Primary and secondary antibodies for ChAT and M1 muscarinic receptors were commercially procured and stained using standard immunohistochemical methods. Results: Preliminary data on E29 rabbit and P5 mouse show comparable immunostaning for ChAT in the inner and the outer retina. In specific, subpopulations of cells were labeled in the inner nuclear layer (INL) and the ganglion cell layers adjacent to the inner plexiform layer (IPL). IPL and the outer plexiform layer (OPL) were also labeled. Labeling of M1 receptors at these ages are also found in IPL and OPL, however labeling of M1 receptors in the inner retina was more restricted to IPL at this age. Conclusions: Cholinergic neurons and muscrarinic receptors are present in both the inner and outer retina during early retinal development. Cholinergic neurotranmission in the ventricular cells may contribute to the formation of spontaneous waves in the VZ.
Keywords: retinal development • retina • immunohistochemistry