Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-25T06:02:58.439Z Has data issue: false hasContentIssue false

Dopaminergic and GABAergic amacrine cells are direct targets of melatonin: Immunocytochemical study of mt1 melatonin receptor in guinea pig retina

Published online by Cambridge University Press:  01 January 2000

HIROKI FUJIEDA
Affiliation:
Neuroendocrinology Research Section, Centre for Addiction and Mental Health, Clarke Division, Toronto, Ontario, Canada Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
JUDITE SCHER
Affiliation:
Neuroendocrinology Research Section, Centre for Addiction and Mental Health, Clarke Division, Toronto, Ontario, Canada Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
SOHEILA A. HAMADANIZADEH
Affiliation:
Neuroendocrinology Research Section, Centre for Addiction and Mental Health, Clarke Division, Toronto, Ontario, Canada
ELLEN WANKIEWICZ
Affiliation:
Neuroendocrinology Research Section, Centre for Addiction and Mental Health, Clarke Division, Toronto, Ontario, Canada Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
SHIU F. PANG
Affiliation:
Department of Physiology, University of Hong Kong, Hong Kong, China
GREGORY M. BROWN
Affiliation:
Neuroendocrinology Research Section, Centre for Addiction and Mental Health, Clarke Division, Toronto, Ontario, Canada Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada

Abstract

Distribution of the mt1 melatonin receptor in the guinea pig retina was immunocytochemically investigated using peptide-specific anti-mt1 receptor antibody. Western blots of the guinea pig retina showed a single band at approximately 37 kilodalton (kD) immunoreactive to the anti-mt1 antibody. The most intense immunoreactivity for the mt1 receptor was detected in the cell bodies of ganglion cells. Their dendrites and axons were also immunolabeled. Subpopulations of amacrine cells, the inner plexiform layer, and the outer plexiform layer also exhibited moderate to weak immunolabeling. The mt1-positive amacrine cells were located either at the vitreal border of the inner nuclear layer or displaced in the ganglion cell layer. Double immunolabeling using antibodies to the mt1 receptor and tyrosine hydroxylase revealed that the majority of dopaminergic amacrine cells showed mt1 immunoreactivity. Almost all the 1CA type dopaminergic cells were mt1 positive while the 2CA type cells less frequently exhibited mt1 immunoreaction. By double immunolabeling for the mt1 receptor and GABA, more than 50% of the mt1-immunoreactive amacrine cells were shown to be GABAergic neurons. Approximately one-third of the GABAergic amacrine cells were immunolabeled for the mt1 receptor. The present results demonstrate expression of the mt1 receptor in diverse neuronal cell types in the guinea pig retina and provide the first evidence for the direct effect of melatonin on dopaminergic and GABAergic amacrine cells via the mt1 receptor.

Type
Research Article
Copyright
© 2000 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)