title: Regeneration of dopaminergic function in 6-hydroxydopamine-lesioned rats by neuroimmunophilin ligand treatment.
abstract: Nonimmunosuppressant immunophilin ligands have been found previously to stimulate neurite growth in culture and to promote regeneration of peripheral and central nerve fibers in vivo. To further characterize the effectiveness of these ligands, we have investigated the effect of the immunophilin ligand GPI-1046 in 6-hydroxydopamine (6-OHDA)-lesioned rats. In unlesioned rats, tetanic stimulation of the white matter induced long-term potentiation (LTP) of corticostriatal synaptic transmission as indicated by a 40-100% increase in the field potential amplitudes recorded in striatal brain slices. Unilateral microinjection of 6-OHDA into the substantia nigra resulted in a loss of corticostriatal LTP and in significant abnormality of motor behavior as assessed by amphetamine-induced ipsilateral rotations. Daily treatment of 6-OHDA-lesioned rats with GPI-1046 (10 mg/kg, s.c.) for 1 week reduced amphetamine-induced rotations by 75% and greatly restored the striatal tyrosine hydroxylase immunostaining. In addition, GPI-1046 almost completely restored corticostriatal LTP in 6-OHDA-lesioned animals. LTP in normal animals and that restored by GPI-1046 in lesioned animals were both blocked by the NMDA receptor antagonist APV, suggesting mediation by NMDA receptors. Both LTPs were sensitive to dopamine (DA) receptor antagonists. The nonselective DA receptor antagonist chlorpromazine and the selective D1-D5 receptor antagonist SCH23390 reduced the LTP by 90%. These results demonstrate that the immunophilin ligand GPI-1046 can reverse the abnormalities in the substantia nigra-striatal dopaminergic system that are caused by 6-OHDA, thus providing a potential therapeutic agent for Parkinson's disease.
authors.affiliation: National Research Council of Canada, Institute for Biological Sciences, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.forename: J P
authors.initials: JP
authors.lastname: Steiner
authors.forename: G S
authors.initials: GS
authors.lastname: Hamilton
authors.forename: T P
authors.initials: TP
authors.lastname: Hicks
authors.forename: M O
authors.initials: MO
authors.lastname: Poulter
mesh_terms: D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002540:Cerebral Cortex / Q000503:physiopathology; D003342:Corpus Striatum / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D018492:Dopamine Antagonists / Q000494:pharmacology; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008024:Ligands; D017774:Long-Term Potentiation / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D016627:Oxidopamine; D010302:Parkinson Disease, Secondary / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D011759:Pyrrolidines / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D020127:Recovery of Function / Q000187:drug effects*; D013378:Substantia Nigra / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D009435:Synaptic Transmission / Q000187:drug effects; D022061:Tacrolimus Binding Protein 1A / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D018492:Dopamine Antagonists; D018691:Excitatory Amino Acid Antagonists; C104949:GPI 1046; D008024:Ligands; D011759:Pyrrolidines; D011954:Receptors, Dopamine; D016194:Receptors, N-Methyl-D-Aspartate; D016627:Oxidopamine; D000661:Amphetamine; D014446:Tyrosine 3-Monooxygenase; D022061:Tacrolimus Binding Protein 1A