Diurnal expression of muscarinic and dopaminergic receptors in the eye of zebrafish




Capalbo, Elizabeth Louise

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Diurnal rhythms allow organisms to synchronize physiological functions, such as feeding habits, with environmental cues such as light and temperature. Much is known about the diurnal and/or circadian regulation of neurotransmitters, but there 1s little to no knowledge of the diurnal or circadian regulation of the G-protein coupled receptors (GPCRs) on which they act. This study sought to determine whether there was a diurnal pattern of gene expression for muscarinic and dopaminerg1c GPCRs and the GPCR regulator, arrestm. Quantitative reverse transnptase polymerase cham reaction was employed on mRNA extracted from whole eye of zebrafish at four time points - dawn, midday, dusk, and midnight - indicated a dmrnal pattern of gene expression for 6 genes out of 11 analyzed, arrestin, D2A, D4A, D4C, M2, and M5 • Reverse transcriptase-PCR of mRNA extracted from different parts of the eye was used to localize expression of the statistically sigmftcantly differentially regulated genes. These results indicate expression of all receptor subtypes in the retma and RPE. Some of the receptors were found m other parts of the eye depending upon time of day, and arrestin was found m all parts at all time points. Immunoh1stochemical analysts of the muscannic M3 receptor and arrestin revealed the protein to be localized to different layers within the retina depending upon the time of day. Taken together, these results suggest that dopaminergic and muscarimc receptors, which have been implicated by others in the regulation of various circadian and diurnal processes in the eye, are themselves, along with arrestin, subject to diurnal regulation.



circadian rhythms, zebra danio, muscarinic receptors, G proteins, gene expression


Capalbo, E. L. (2009). Diurnal expression of muscarinic and dopaminergic receptors in the eye of zebrafish (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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