Differential expression of D2-like dopamine receptors in the kidney of the spontaneously hypertensive rat.
OBJECTIVE
To compare the expression and cellular distribution of D(2)-like dopamine receptors in the kidney of the spontaneously hypertensive rat (SHR) and normotensive Wistar-Kyoto (WKY) rat.


METHODS
Renal D(2)-like receptor protein expression and distribution has not been studied in the SHR. Since changes in D(2)-like receptor expression and/or distribution may contribute to the dysregulation of renal dopamine and D(1A) receptor function, we examined the expression of the three subtypes of D(2)-like receptors (D(2), D(3) and D(4)) in SHR and WKY rat kidneys.


METHODS
Western blot analysis and confocal immunocytochemistry with specific polyclonal antipeptide antibodies directed against the receptor subtypes, were used to assess protein expression.


RESULTS
There were no differences in protein expression and cellular immunolocalization of the D(2) receptor subtypes between SHR and WKY rats. Expression of the 50 kDa D(3) receptor was reduced in the cortex of the SHR; no differences in D(3) receptor levels were seen in the inner medulla of SHR and WKY rats. The D(4) receptor polypeptides were overexpressed in the cortex of SHR, while in the inner medulla no difference in expression of the D(4) receptor proteins was observed between SHR and WKY rats. Immunocytochemistry also showed increased immunostaining of D(4) receptors in tubular structures in the cortex, but diminished staining in the SHR inner medulla.


CONCLUSIONS
The observed differences in expression and distribution of D(3) and D(4) dopamine receptors between cortex and inner medulla of the kidneys of SHR and WKY rats may contribute to the aberrant state of dopaminergic-mediated natriuresis in SHR.
Shin
Yangmee
Y
Department of Pediatrics, Georgetown University Medical Center, 3970 Reservoir Road NW, Washington, DC 20007, USA.
Kumar
Ujendra
U
Patel
Yogesh
Y
Patel
Shutish C
SC
Sidhu
Anita
A
D000818:Animals; D015153:Blotting, Western; D006973:Hypertension / Q000378:metabolism*; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4; D014018:Tissue Distribution
C493595:Drd3 protein, rat; C493601:Drd4 protein, rat; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4