Molecular characterization of individual D3 dopamine receptor-expressing cells isolated from multiple brain regions of a novel mouse model

Abstract

Among dopamine receptors, the expression and function of the D3 receptor subtype is not well understood. The receptor has the highest affinity for dopamine and many drugs that target dopamine receptors. In this paper, we examined, at the single cell level, the characteristics of D3 receptor-expressing cells isolated from different brain regions of male and female mice that were either 35 or 70 days old. The brain regions included nucleus accumbens, Islands of Calleja, olfactory tubercle, retrosplenial cortex, dorsal subiculum, mammillary body, amygdala and septum. The expression analysis was done in the drd3-enhanced green fluorescent protein transgenic mice that report the endogenous expression of D3 receptor mRNA. Using single cell reverse transcriptase PCR, we determined if the D3 receptor-expressing fluorescent cells in these mice were neurons or glia and if they were glutamatergic, GABAergic or catecholaminergic. Next, we determined if the fluorescent cells co-expressed the four other dopamine receptor subtypes, adenylate cyclase V (ACV) isoform, and three different isoforms of G protein-coupled inward rectifier potassium (GIRK) channels. The results suggest that D3 receptor is expressed in neurons, with region-specific expression in glutamatergic and GABAergic neurons. The D3 receptor primarily co-expressed with D1 and D2 dopamine receptors with regional, sex and age-dependent differences in the co-expression pattern. The percentage of cells co-expressing D3 receptor and ACV or GIRK channels varied significantly by brain region, sex and age. The molecular characterization of D3 receptor-expressing cells in mouse brain reported here will facilitate the characterization of D3 receptor function in physiology and pathophysiology.

Identification of key residues involved in the activation and signaling properties of dopamine D3 receptor

“…Mary Beth Hatten and Nathaniel Heintz (GENSAT program, Rockefeller University) and a local breeding colony was established at Rutgers-New Jersey Medical School. The drd3-EGFP reporter mice are on a mixed Swiss Webster/FVB genetic background and have been recently characterized by us in detail [19,27]. The mice were weaned on post natal day 21 and group housed (4 or less mice per cage) with littermates in a temperature and humidity controlled environment, with a 12hr light (on at 7 A.M.): dark (off at 7 P.M.) cycle.…”

“…The drd3-EGFP transgenic mouse model expresses the enhanced green fluorescent protein (EGFP) under the control of the D3 receptor promoter, resulting in the expression of the EGFP protein in cells that endogenously express the native D3 receptor mRNA [27]. We have recently used drd3-EGFP model to show that D3 receptor tolerance property is observed in the D3 receptor-MAPK signaling pathway and at behavior level [19].…”

Sex differences in the neural mechanisms mediating addiction: a new synthesis and hypothesis

“…Interestingly, a greater proportion of D3-containing neurons in the amygdala also co-express D1 and D2 receptors in females, relative to males, a pattern that emerges after puberty [270]. Thus, the activation of DA receptors in the CeA/BST may induce very different signaling cascades in males and females.…”

Chronic levodopa treatment alters expression and function of dopamine D3 receptor in the MPTP/p mouse model of Parkinson’s disease

“…Mary Beth Hatten and Nathaniel Heintz (GENSAT program, Rockefeller University) and a breeding colony was established at Rutgers University-New Jersey Medical School. The drd3-EGFP reporter mice have been previously characterized by us in detail [11, 15]. Mice were group-housed (4 or less per cage) with littermates in a temperature and humidity controlled environment, with a 12 hr light (on at 7 A.M.): dark (off at 7 P.M.) cycle.…”