Putative neuropathological interactions in MSA: focus in the rostral ventrolateral medulla.

We used double immunocytochemistry for α-synuclein and markers of sympathoexcitatory neurons, oligodendrocytes, iron metabolism, and autophagy to study putative neuropathological interactions in multiple system atrophy. We focused in the rostral ventrolateral medulla as a prototype vulnerable region. We found that loss of C1 neurons and oligodendrocytes related to glial cytoplasmic inclusion accumulation, downregulation of iron transport, and upregulation of autophagy and ferritin expression in these area.

Mechano growth factor interacts with nucleolin to protect against cisplatin-induced neurotoxicity.

Mechano growth factor (MGF) is an alternatively spliced form of insulin-like growth factor-1 (IGF-1) that has shown to be neuroprotective against 6-hydroxydopamine toxicity and ischemic injury in the brain. MGF also induces neural stem cell proliferation in the hippocampus and preserves olfactory function in aging mice. Cisplatin is a chemotherapy drug that induces peripheral neuropathy in 30-40% of treated patients. Our studies were designed to see if MGF would protect dorsal root ganglion (DRG) neurons from cisplatin-induced neurotoxicity and to identify potential mechanisms that may be involved. Expression of endogenous MGF in adult DRG neurons in vivo ameliorated cisplatin-induced thermal hyperalgesia. Exogenous MGF and MGF with a cysteine added to the N-terminus (CMGF) also protected embryonic DRG neurons from cisplatin-induced cell death in vitro. Mass spectroscopy analysis of proteins bound to MGF showed that nucleolin is a key-binding partner. Antibodies against nucleolin prevented the neuroprotective effect of MGF and CMGF in culture. Both nucleolin and MGF are located in the nucleolus of DRG neurons. RNAseq of RNA associated with MGF indicated that MGF may be involved in RNA processing, protein targeting and transcription/translation. Nucleolin is an RNA binding protein that is readily shuttled between the nucleus, cytoplasm and plasma membrane. Nucleolin and MGF may work together to prevent cisplatin-induced neurotoxicity. Exploring the known mechanisms of nucleolin may help us better understand the mechanisms of cisplatin toxicity and how MGF protects DRG neurons.

Involvement of the ventrolateral medulla in parkinsonism with autonomic failure.

OBJECTIVE: To determine whether patients with PD and autonomic failure (AF), manifested primarily with orthostatic hypotension (OH), have a consistent loss of tyrosine hydroxylase (TH) neurons in the rostral ventrolateral medulla (RVLM), similar to that occurring in patients with multiple system atrophy (MSA) and AF, and to determine whether there is loss of nicotinamide, adenine dinucleotide phosphate (NADPH) diaphorase (NADPH-d) RVLM neurons in both groups of patients. METHODS: The numbers of TH and NADPH-d neurons in the RVLM was assessed in brain sections obtained at autopsy from five patients with suspected PD and OH, six patients with MSA, two patients with corticobasal ganglionic degeneration and no AF, and 10 control subjects with no history of neurologic disease. Cell numbers were compared among groups and correlated with their final neuropathologic diagnosis. RESULTS: The number of TH neurons in the RVLM of patients with PD and OH were not significantly different from control subjects, and there were marked individual variations. The TH cell numbers in the RVLM were significantly higher (p < 0.06) in patients with PD than in patients with MSA, despite a similar degree of severity of OH. As a group, patients with PD and OH had reduced numbers of NADPH-d cells in the RVLM compared with control subjects, but again there were marked individual variations. NADPH-d cell numbers were reduced consistently and more markedly in patients with MSA. CONCLUSION: Unlike the case in patients with MSA, the number of TH neurons in the RVLM is highly variable in patients with PD and is unlikely to contribute significantly to the pathophysiology of OH. As a group, patients with PD have reduced numbers of NADPH-d neurons in the RVLM, but some patients had cell counts similar to control subjects. On the other hand, NADPH-d cell depletion in the RVLM is a consistent finding in MSA and may contribute to cardiorespiratory dysfunction in this disorder.

Immunohistochemical localization of the angiotensin II type 1 receptor in human hypothalamus and brainstem.

We studied the distribution of the angiotensin II type 1 (AT-1) receptor using a polyclonal rabbit antibody in two human brains. AT-1 receptor immunoreactivity was detected in several hypothalamic nuclei, substantia nigra, locus coeruleus, nucleus tractus solitarius, ventrolateral medulla, pontine nuclei, and inferior olivary nucleus. This provides direct evidence of neuronal localization of the AT-1 receptor in autonomic and motor areas in human brain.

Depletion of cholinergic neurons of the medullary arcuate nucleus in multiple system atrophy.

The human arcuate nucleus (ArcN) has been considered akin to the pontine precerebellar nuclei. However, there is anatomical, functional, and clinical evidence that the ArcN may be the homologue of chemosensitive areas of the ventral medullary surface involved in ventilatory responses to hypercarbia and cerebrospinal fluid acidosis. Acetylcholine has been involved in mechanisms of central chemosensitivity. Loss of ArcN neurons has been reported in patients with multiple system atrophy (MSA), a disorder characterized by disturbed automatic ventilation, but the neurochemical identity of these neurons is undetermined. We sought to determine whether the ArcN contains cholinergic neurons and whether these neurons are depleted in patients with MSA. Medullae were obtained from six patients with MSA, five patients with Parkinson's disease (PD) and six sex- and age-matched controls. Fifty-micron transverse sections obtained through the mid-olivary levels were processed for acetylcholinesterase (AchE), choline acetyltransferase (CAT), and alpha-synuclein immunoreactivity. We found that the ArcN contained CAT-positive neurons. There was a significant decrease in density of cholinergic ArcN neurons in MSA but not in PD patients. alpha-Synuclein-containing inclusions were present in the ArcN of MSA patients. Depletion of cholinergic neurons may provide a substrate for disturbances in automatic respiration in MSA patients.

Parabrachial nucleus involvement in multiple system atrophy.

UNLABELLED: Multiple system atrophy (MSA) is associated with respiratory dysfunction, including sleep apnea, respiratory dysrhythmia, and laryngeal stridor. Neurons of the parabrachial nucleus (PBN) control respiratory rhythmogenesis and airway resistance. OBJECTIVES: The objective of this study is to determine whether there was involvement of putative respiratory regions of the PBN in MSA. METHODS: We examined the pons at autopsy in 10 cases with neuropathologically confirmed MSA and 8 age-matched controls. Sections obtained throughout the pons were processed for calcitonin-gene related peptide (CGRP) and Nissl staining to identify the lateral crescent of the lateral PBN (LPB) and the Kölliker-Fuse nucleus (K-F), which are involved in respiratory control. Cell counts were performed using stereology. RESULTS: There was loss of CGRP neurons in the PBN in MSA (total estimated cell counts for the external LPB cluster was 12,584 ± 1146 in controls and 5917 ± 389 in MSA, p<0.0001); for the external medial PBN (MPB) cluster it was 15,081 ± 1758 in controls and 7842 ± 466 in MSA, p<0.001. There was also neuronal loss in putative respiratory regions of the PBN, including the lateral crescent of the LPB (13,039 ± 1326 in controls and 4164 ± 872 in MSA, p<0.0001); and K-F (5120 ± 495 in controls and 999 ± 308 in MSA, p<0.0001). CONCLUSIONS: There is involvement of both CGRP and putative respiratory cell groups in the PBN in MSA. Whereas the clinical implications of CGRP cell loss are still undetermined, involvement of the LPB and K-F may contribute to respiratory dysfunction in this disorder.

Clinicopathologic correlations in 172 cases of rapid eye movement sleep behavior disorder with or without a coexisting neurologic disorder.

OBJECTIVE: To determine the pathologic substrates in patients with rapid eye movement (REM) sleep behavior disorder (RBD) with or without a coexisting neurologic disorder. METHODS: The clinical and neuropathologic findings were analyzed on all autopsied cases from one of the collaborating sites in North America and Europe, were evaluated from January 1990 to March 2012, and were diagnosed with polysomnogram (PSG)-proven or probable RBD with or without a coexisting neurologic disorder. The clinical and neuropathologic diagnoses were based on published criteria. RESULTS: 172 cases were identified, of whom 143 (83%) were men. The mean±SD age of onset in years for the core features were as follows - RBD, 62±14 (range, 20-93), cognitive impairment (n=147); 69±10 (range, 22-90), parkinsonism (n=151); 68±9 (range, 20-92), and autonomic dysfunction (n=42); 62±12 (range, 23-81). Death age was 75±9 years (range, 24-96). Eighty-two (48%) had RBD confirmed by PSG, 64 (37%) had a classic history of recurrent dream enactment behavior, and 26 (15%) screened positive for RBD by questionnaire. RBD preceded the onset of cognitive impairment, parkinsonism, or autonomic dysfunction in 87 (51%) patients by 10±12 (range, 1-61) years. The primary clinical diagnoses among those with a coexisting neurologic disorder were dementia with Lewy bodies (n=97), Parkinson's disease with or without mild cognitive impairment or dementia (n=32), multiple system atrophy (MSA) (n=19), Alzheimer's disease (AD)(n=9) and other various disorders including secondary narcolepsy (n=2) and neurodegeneration with brain iron accumulation-type 1 (NBAI-1) (n=1). The neuropathologic diagnoses were Lewy body disease (LBD)(n=77, including 1 case with a duplication in the gene encoding α-synuclein), combined LBD and AD (n=59), MSA (n=19), AD (n=6), progressive supranulear palsy (PSP) (n=2), other mixed neurodegenerative pathologies (n=6), NBIA-1/LBD/tauopathy (n=1), and hypothalamic structural lesions (n=2). Among the neurodegenerative disorders associated with RBD (n=170), 160 (94%) were synucleinopathies. The RBD-synucleinopathy association was particularly high when RBD preceded the onset of other neurodegenerative syndrome features. CONCLUSIONS: In this large series of PSG-confirmed and probable RBD cases that underwent autopsy, the strong association of RBD with the synucleinopathies was further substantiated and a wider spectrum of disorders which can underlie RBD now are more apparent.

Dopamine cell loss in the periaqueductal gray in multiple system atrophy and Lewy body dementia.

BACKGROUND: Experimental studies indicate that dopaminergic neurons in the ventral periaqueductal gray matter (PAG) are involved in maintenance of wakefulness. Excessive daytime sleepiness (EDS) is a common manifestation of multiple system atrophy (MSA) and dementia with Lewy bodies (DLB) but involvement of these neurons has not yet been explored. METHODS: We sought to determine whether there is loss of dopaminergic neurons in the ventral PAG in MSA and DLB. We studied the midbrain obtained at autopsy from 12 patients (9 male, 3 female, age 61 +/- 3) with neuropathologically confirmed MSA, 12 patients (11 male, 1 female, age 79 +/- 4) with diagnosis of DLB and limbic or neocortical Lewy body disease, and 12 controls (7 male, 5 female, ages 67 +/- 4). Fifty-micron sections were immunostained for tyrosine hydroxylase (TH) or alpha-synuclein and costained with thionin. Cell counts were performed every 400 mum throughout the ventral PAG using stereologic techniques. RESULTS: Compared to the total estimated cell numbers in controls (21,488 +/- 8,324 cells), there was marked loss of TH neurons in the ventral PAG in both MSA (11,727 +/- 5,984; p < 0.01) and DLB (5,163 +/- 1,926; p < 0.001) cases. Cell loss was more marked in DLB than in MSA. There were characteristic alpha-synuclein inclusions in the ventral PAG in both MSA and DLB. CONCLUSIONS: There is loss of putative wake-active ventral periaqueductal gray matter dopaminergic neurons in both multiple system atrophy and dementia with Lewy bodies, which may contribute to excessive daytime sleepiness in these conditions.

Mesopontine cholinergic neuron involvement in Lewy body dementia and multiple system atrophy.

BACKGROUND: The pedunculopontine (PPT) and laterodorsal (LDT) tegmental nuclei are involved in control of REM sleep and thalamocortical arousal. REM sleep behavior disorder (RBD) is a feature of multiple system atrophy (MSA) and dementia with Lewy bodies (DLB), which is also associated with visual hallucinations and cognitive fluctuations. We sought to determine the degree of PPT/LDT involvement in DLB compared to MSA. METHODS: We counted the cholinergic neurons in the PPT and LDT in 13 patients with neuropathologically confirmed DLB, 11 patients with MSA, and 11 control cases. Five patients with DLB and eight patients with MSA had history or polysomnographic evidence of RBD. Ten patients with DLB and no patient with MSA had history of visual hallucinations or cognitive fluctuations. RESULTS: There was a significant loss of PPT and LDT neurons in both DLB and MSA. Cell loss in both the PPT and LDT was more severe in MSA than in DLB. The number of cells/section for the PPT were 148 +/- 21 in controls, 54 +/- 10 in DLB (p < 0.001), and 20 +/- 3 in MSA (p < 0.001), and for the LDT, 112 +/- 16 in controls, 49 +/- 8 in DLB (p < 0.01), and 16 +/- 2 in MSA (p < 0.001). Severity of neuronal loss in MSA or DLB did not relate to the presence or absence of history of RBD. CONCLUSIONS: Loss of cholinergic pedunculopontine tegmental nuclei/laterodorsal tegmental nuclei neurons occurs in both dementia with Lewy bodies and multiple system atrophy but is probably not the primary mechanism of REM sleep behavior disorder in these disorders.

Rostral raphe involvement in Lewy body dementia and multiple system atrophy.

Depression is a feature of both Lewy body disorders and multiple system atrophy (MSA). Since serotonergic neurons of the rostral raphe have been implicated in depression, we sought to determine whether there is a differential involvement of these neurons in cases with clinically diagnosed dementia with Lewy bodies (DLB) or MSA. We studied the brainstem obtained at autopsy from fourteen patients with diagnosis of DLB and pathological limbic or neocortical stage Lewy body disease, 13 patients with clinical and neuropathological diagnosis of MSA, and 12 controls with no history of neurologic disease. The clinical features of these patients were analyzed retrospectively by reviewing their medical records. Serial sections were immunostained for tryptophan hydroxylase (TrOH) and alpha-synuclein and cell counts were performed in the dorsal raphe (DR), median raphe (MR) and medullary raphe nuclei. There was loss of serotonergic cells in both the DR and MR in DLB compared to control cases: For the DR, the number of cells/section were 53 +/- 6 in DLB versus 159 +/- 13 (P < 0.001) respectively, and for the MR 70 +/- 11 in DLB versus 173 +/- 23 (P < 0.001) respectively. In contrast, these cells were relatively preserved in MSA. The caudal raphe groups were affected both in MSA and in DLB. There is a differential involvement of raphe neurons in DLB and MSA. Although loss of rostral raphe neurons may contribute to depression in DLB, this appears to be less likely in MSA. Factors other than the neurochemical phenotype determine neuronal vulnerability in MSA.

Involvement of vagal autonomic nuclei in multiple system atrophy and Lewy body disease.

BACKGROUND: Multiple system atrophy (MSA) and Lewy body disorders (LBDs) are associated with impaired control of gastrointestinal and cardiac functions. The dorsal vagal nucleus (DMV) innervates enteric neurons, whereas the ventrolateral nucleus ambiguus (NAmb) innervates the heart. The relationship between DMV and NAmb involvement and the gastrointestinal or cardiovagal manifestations in MSA and LBD is unclear. METHODS: The authors counted the cholinergic neurons in the DMV and NAmb in 15 cases of neuropathologically confirmed MSA, 14 of LBD (4 brainstem, 3 limbic, and 7 neocortical), and 12 control cases. All MSA and 8 of the 14 LBD cases had gastrointestinal symptoms; 8 of 12 MSA and 1 of 4 LBD cases had laboratory evidence of cardiovagal failure; 5 of the MSA and no LBD cases had laryngeal stridor. RESULTS: There was loss of cholinergic DMV neurons in all MSA and LBD cases. The degree of DMV cell loss was similar in LBD patient with or without gastrointestinal symptoms. In MSA but not in LBD cases, there was neuronal loss in the ventrolateral NAmb, with lower counts in patients with cardiovagal failure. CONCLUSIONS: There is comparable involvement of the dorsal vagal nucleus (DMV) in multiple system atrophy (MSA) and different stages of Lewy body disorders (LBDs). The relationship of DMV involvement and gastrointestinal symptoms is uncertain. Loss of neurons in the ventrolateral nucleus ambiguus may explain the more consistent cardiovagal failure in MSA than in LBD.

Depletion of corticotrophin-releasing factor neurons in the pontine micturition area in multiple system atrophy.

We sought to determine whether the putative pontine micturition center in the human dorsal pons contains corticotrophin-releasing factor (CRF) neurons, and whether these neurons are depleted in patients with multiple system atrophy and bladder dysfunction. Brains were obtained at autopsy from 4 control subjects and 4 patients with clinical diagnosis of multiple system atrophy, confirmed neuropathologically. Serial 50 microm cryostat sections were obtained throughout the rostral half of the pons, and every eighth section was processed for CRF immunocytochemistry (rabbit polyclonal antibody). Consecutive sections were stained for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) to identify neurons of the laterodorsal tegmental nucleus or for both CRF and NADPH. Locus ceruleus neurons were identified by their neuromelanin content. Abundant CRF immunoreactive neurons were identified in the dorsal pontine tegmentum just ventral to the locus ceruleus. CRF neurons were intermingled with, but distinct from, the NADPH-d-reactive neurons of the laterodorsal tegmental nucleus. In all multiple system atrophy cases, there was a severe depletion of these CRF-immunoreactive neurons (26.6 +/- 3 neurons/section in patients; 73.7 +/- 4 neurons/section in controls). Our results suggest that depletion of CRF neurons in the putative pontine micturition center may contribute to the severe bladder dysfunction that characterizes multiple system atrophy.

Synucleinopathy pathology and REM sleep behavior disorder plus dementia or parkinsonism.

OBJECTIVE: To determine if synucleinopathy pathology is related to REM sleep behavior disorder (RBD) plus dementia or parkinsonism. METHODS: The clinical and neuropathologic findings were analyzed on all autopsied cases evaluated at Mayo Clinic Rochester from January 1990 to April 2002 who were diagnosed with RBD and a neurodegenerative disorder. Ubiquitin and/or alpha-synuclein immunocytochemistry was used in all cases. The clinical and neuropathologic diagnoses were based on published criteria. RESULTS: Fifteen cases were identified (14 men). All had clear histories of dream enactment behavior, and 10 had RBD confirmed by polysomnography. RBD preceded dementia or parkinsonism in 10 (66.7%) patients by a median of 10 (range 2 to 29) years. The clinical diagnoses included dementia with Lewy bodies (DLB) (n = 6); multiple-system atrophy (MSA) (n = 2); combined DLB, AD, and vascular dementia (n = 1); dementia (n = 1); dementia with parkinsonism (n = 1); PD (n = 1); PD with dementia (n = 1); dementia/parkinsonism/motor neuron disease (n = 1); and AD/Binswanger's disease (n = 1). The neuropathologic diagnoses were Lewy body disease (LBD) in 12 (neocortical in 11 and limbic in 1) and MSA in 3. Three also had argyrophilic grain pathology. In the LBD cases, concomitant AD pathology was present in six (one also with Binswanger's pathology, and one also with multiple subcortical infarcts). CONCLUSION: In the setting of degenerative dementia or parkinsonism, RBD often reflects an underlying synucleinopathy.