The effects of nicotine on cone and rod b-wave responses in larval zebrafish

Abstract

Acetylcholine is present in and released from starburst amacrine cells in the inner plexiform layer (INL), but its role in retinal function except, perhaps, in early development, is unclear. Nicotinic acetylcholine receptors are thought to be present on ganglion, amacrine and bipolar cells processes in the IPL, and it is known that acetylcholine increases the spontaneous and light-evoked responses of retinal ganglion cells. The effects of acetylcholine on bipolar cells is not known, and here we report the effects of nicotine on the b-wave of the ERG in larval zebrafish. The b-wave originates mainly from ON-bipolar cells and in the larval zebrafish retina is cone-dominated. Only small rod responses can be elicited with dim lights in wild-type larval zebrafish retinas but rod responses can be recorded over a range of intensities in a mutant (nof) fish that has no cone function. We find that nicotine strongly enhances cone-driven b-wave response amplitudes but depresses rod driven b-wave response amplitudes without,however, affecting rod or cone driven b-wave light sensitivity.