title: A non-cholinergic neuronal loss in the pedunculopontine nucleus of toxin-evoked parkinsonian rats.
abstract: The pedunculopontine nucleus (PPN) controls various physiological functions, whilst being deemed a suitable target for low-frequency stimulation therapy for alleviating aspects of Parkinson's disease (PD). Previous studies showed that the PPN contains mainly cholinergic, γ-aminobutyric acid (GABA)ergic and glutamatergic neurons. Here we report on the total number of PPN neurons in laboratory rats, a species frequently used as an experimental model for simulating aspects of human PD. Moreover, the study reports that the number of PPN neurons decreases under toxic conditions that mimic in animals the core pathology seen in human PD. Immunohistochemical detection methods combined with unbiased stereology served to estimate that the PPN of healthy rats unilaterally contains ~19,028 NeuN-immunopositive neurons. The identified neurons revealed a distinct distribution pattern consisting of high cell density in the most rostral and caudal sections of the PPN nucleus, contrasting with lower densities in the medial segments. Our data also show a significant loss which affected PPN non-cholinergic cells, but not cholinergic ones in rats lesioned unilaterally in the Substantia Nigra pars compacta (SNpc) with a single injection of 6-hydroxydopamine (6-OHDA) compared to control animals. This result differs from previous studies which reported a substantial cholinergic cell loss in the PPN of post-mortem PD brains and in 6-OHDA-lesioned monkeys. Since a noted demise of dopaminergic neurons residing in the SN was confirmed in the 6-OHDA-lesioned rats, the current study suggests that a "dying-back" mechanism may underlie the cell death affecting non-cholinergic PPN neurons.
authors.affiliation: Centre for NeuroInflammation & Neurodegeneration, Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, United Kingdom. Electronic address: i.pienaar@imperial.ac.uk.
authors.forename: Ilse S
authors.initials: IS
authors.lastname: Pienaar
authors.forename: Wilma
authors.initials: W
authors.lastname: van de Berg
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D034961:Antigens, Nuclear / Q000378:metabolism; D016923:Cell Death; D059329:Cholinergic Neurons / Q000378:metabolism / Q000473:pathology; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D016627:Oxidopamine; D010302:Parkinson Disease, Secondary / Q000378:metabolism / Q000473:pathology*; D045042:Pedunculopontine Tegmental Nucleus / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000378:metabolism / Q000473:pathology
chemical_list: D034961:Antigens, Nuclear; D009419:Nerve Tissue Proteins; C546339:Rbfox3 protein, rat; D016627:Oxidopamine; D000109:Acetylcholine
keywords: (+); 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; 4′,6-diamidino-2-phenylindole; 6-OHDA; 6-hydroxydopamine; ABC; Avidin–biotin-complex; CCD; CFV; Charge-coupled device; Cholinergic; Cresyl Fast Violet; DA; DAB; DAPI; DBS; Deep-brain stimulation; Diaminobenzidine dihydrochloride; Dopamine; EtOH; Ethanol; HuC/D; Human neuronal protein; Immunopositive; LDTg; Laterodorsal tegmental nucleus; MPTP; NDS; NeuN; Neuronal-specific nuclear protein; Non-cholinergic; Normal donkey serum; PD; PFA; PPN; Parkinson's disease; Pedunculopontine nucleus; REM; RT; Rapid eye movement; Room temperature; SNCA [protein]; SNpc; SNr; STN; Stereology; Substantia Nigra pars compacta; Substantia Nigra pars reticulata; Subthalamic nucleus; TH; Tyrosine hydroxylase; paraformaldehyde; α-synuclein