Involvement of dopamine D(2)/D(3) receptors and BDNF in the neuroprotective effects of S32504 and pramipexole against 1-methyl-4-phenylpyridinium in terminally differentiated SH-SY5Y cells.
Anti-parkinsonian agents possessing both D(2) and D(3) receptor agonist properties are neuroprotective against 1-methyl-4-phenylpyridinium (MPP(+)) toxicity in a variety of in vitro models. The mechanisms underlying protection by these D(2)/D(3) receptor agonists remain poorly defined. To test if the D(3) receptor preferring agonists S32504 and pramipexole act through D(2) or D(3) receptors and via brain-derived neurotrophic factor (BDNF)-dependent pathways, we utilized a terminally differentiated neuroblastoma SH-SY5Y cell line exhibiting a dopaminergic phenotype. The cytotoxic effects of MPP(+) (LD(50) of 100 microM) were stereospecifically antagonized by S32504 (EC(50) = 2.0 microM) and, less potently, by pramipexole (EC(50) = 64.3 microM), but not by their inactive stereoisomers, R(+) pramipexole and S32601, respectively. Neuroprotective effects afforded by EC(50) doses of S32504 and pramipexole were antagonized by the selective D(3) antagonists S33084, U99194A, and SB269652, and by the D(2)/D(3) antagonist raclopride. However, the preferential D(2) receptor antagonist LY741626 was ineffective as was the D1 antagonist SCH23390. BDNF (1 nM) potently protected against MPP(+)-induced neurotoxicity. Antibody directed against BDNF concentration-dependently blocked both the neuroprotective effects of BDNF and those of pramipexole and S32504 against MPP(+). The protection afforded by BDNF was blocked by the P3K-AKT pathway inhibitor LY249002 and less so by the MEK/MAPKK pathway inhibitor PD98059. LY249002, but not PD98059, blocked the neuroprotective effects of pramipexole and S32504 against MPP(+) toxicity. In conclusion, S32504 and, less potently, pramipexole show robust, stereospecific, and long-lasting neuroprotective effects against MPP(+) toxicity that involve D(3) receptors. Their actions also reflect downstream recruitment of BDNF and via a PK3-AKT pathway.
Thomas H. Christopher Center for Parkinson's Disease Research, Sun Health Research Institute, 10515 West Santa Fe Drive, Sun City, AZ 85351, USA.
Steve P
SP
Presgraves
Sabine
S
Borwege
Mark J
MJ
Millan
Jeffrey N
JN
Joyce
D015655:1-Methyl-4-phenylpyridinium / Q000037:antagonists & inhibitors / Q000633:toxicity; D000906:Antibodies / Q000494:pharmacology; D052160:Benzothiazoles; D019208:Brain-Derived Neurotrophic Factor / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology; D010078:Oxazines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000077487:Pramipexole; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013844:Thiazoles / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014212:Tretinoin / Q000494:pharmacology
D000906:Antibodies; D052160:Benzothiazoles; D019208:Brain-Derived Neurotrophic Factor; C493593:DRD3 protein, human; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D010078:Oxazines; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; C478818:S 32504; D013844:Thiazoles; D014212:Tretinoin; D000077487:Pramipexole; D013755:Tetradecanoylphorbol Acetate; D015655:1-Methyl-4-phenylpyridinium