Expression of Alpha 7 Nicotinic Acetylcholine Receptors by Bipolar, Amacrine, and Ganglion Cells of the Rabbit Retina

Abstract

Cholinergic agents affect the light responses of many ganglion cells (GCs) in the mammalian retina by activating nicotinic acetylcholine receptors (nAChRs). Whereas retinal neurons that express β2 subunit-containing nAChRs have been characterized in the rabbit retina, expression patterns of other nAChR subtypes remain unclear. Therefore, we evaluated the expression of α7 nAChRs in retinal neurons by means of single-, double-, and triple-label immunohistochemistry. Our data demonstrate that, in the rabbit retina, several types of bipolar cells, amacrine cells, and cells in the GC layer express α7 nAChRs. At least three different populations of cone bipolar cells exhibited α7 labeling, whereas glycine-immunoreactive amacrine cells comprised the majority of α7-positive amacrine cells. Some GABAergic amacrine cells also displayed α7 immunoreactivity; α7 labeling was never detected in rod bipolar cells or rod amacrine cells (All amacrine cells). Our data suggest that activation of α7 nAChRs by acetylcholine (ACh) or choline may affect glutamate release from several types of cone bipolar cells, modulating GC responses. ACh-induced excitation of inhibitory amacrine cells might cause either inhibition or disinhibition of other amacrine and GC circuits. Finally, ACh may act on α7 nAChRs expressed by GCs themselves.

Role of acetylcholine in nitric oxide production in the salamander retina

“…Following the protocol of Dmitrieva et al (2007), isolated retinas from four salamander eyes were homogenized in four volumes of ice-cold lysis buffer: PBS containing 1% NP-40, 0.5% sodium deoxycholate, 0.1% sodium dodecyl sulfate (SDS), protease inhibitor cocktail (1:30), and incubated at 4°C for 30 minutes, then centrifuged (15,000g at 4°C for 30 minutes). The supernatant was retained and mixed with an equal amount of sample buffer.…”

Alpha7 nicotinic acetylcholine receptor agonist promotes retinal ganglion cell function via modulating GABAergic presynaptic activity in a chronic glaucomatous model

“…In isolated/cultured porcine and salamander RGCs, the neuroprotective effects of nAChR agonists against glutamate-induced excitotoxicity are mediated by the Ca 2+ -phosphatidylinositol 3-Akt-Bcl2 and NF-κβ cell survival signaling pathway, and via the mitogen-activated protein kinase apoptosis pathway 5–11 . Previous studies have demonstrated that α7-nAChRs are expressed in retinal bipolar, amacrine, and ganglion cells in normal mice and rabbits 12–14 . However, it is unclear whether activation of α7-nAChRs exerts a neuroprotective role in a chronic in vivo rat glaucoma model produced by episcleral vein cautery.…”

Color Discrimination Performance in Patients with Alzheimer’s Disease

“…Some evidence supports the idea that there may be a specific involvement of the sensory visual system. A primary retinal involvement appears plausible since cholinergic and glutamatergic systems are impaired in AD [7] . In the retina, light-activated photoreceptors transmit signals to bipolar and ganglionar cells via glutamate and aspartate neural transmission.…”

“…In the retina, light-activated photoreceptors transmit signals to bipolar and ganglionar cells via glutamate and aspartate neural transmission. Furthermore, amacrine cells, which are specifically involved in chromatic light stimulus transmission, utilize acetylcholine as a neurochemical mediator [7] .…”