Neurohumoral regulation of spontaneous constrictions in suburothelial venules of the rat urinary bladder

Venules of the bladder suburothelium develop spontaneous phasic constrictions that may play a critical role in maintaining venular drainage of tissue metabolites. We aimed to investigate neurohumoral regulation of the spontaneous venular constrictions (SVCs). Changes in venular diameter of the rat bladder suburothelium were monitored using a video tracking system, whilst the effects of electrical field stimulation (EFS) and bath-applied bioactive substances were investigated. The innervation of the suburothelial microvasculature was examined by immunohistochemistry. EFS (10 Hz for 30 s) induced an increase in the frequency of SVCs that was prevented by phentolamine (1 μM). In phentolamine-pretreated venules, EFS suppressed SVCs with a venular dilatation in a manner attenuated by propranolol (1 μM) or l-nitro arginine (LNA, 10 μM). BRL37344 (1 μM), a β₃ adrenoceptor agonist, dilated venules and reduced the frequency of SVCs in an LNA-sensitive manner. ACh (1–10 μM) increased the frequency of SVCs. ATP (1 μM) transiently constricted venules and then caused LNA-sensitive cessation of SVCs associated with a dilatation. Substance P (100 nM) caused a venular constriction, whilst calcitonin gene related peptide (CGRP, 100 nM) caused a dilatation of venules and suppression of SVCs that were not inhibited by LNA. Immunohistochemical staining demonstrated sympathetic as well as substance P- and CGRP-containing nerves running along the venules. Spontaneous constrictions of suburothelial venules are accelerated by sympathetic α-adrenergic stimulation, but suppressed upon β-adrenergic stimulation. In addition, suburothelial venular constrictions appear to be modulated by several bioactive substances that could be released from urothelium or suburothelial sensory nerves.     

Clinical features of argyrophilic grain disease: a retrospective survey of cases with neuropsychiatric symptoms.

OBJECTIVE: Although argyrophilic grain disease (AGD) appears common in post-mortem series, its clinical features are not widely known. The aim of this study was to explore such clinical features in neuropathologically-confirmed AGD cases. METHODS: After completing a neuropathological assessment of 386 patients, 33 cases (8.5%) were diagnosed as having AGD; 10 were diagnosed as "pure" cases. These subjects had been admitted to geriatric wards of mental hospitals because of behavioral or neuropsychiatric symptoms requiring medical management. Assessment of the clinical features of the pure cases was based on the evaluations in medical records. RESULTS: The average age at onset was 82.2 years. Amnesia was the most common initial symptom; irritability and agitation were also common as initial symptoms. During the course of the illness, irritability was the most frequently observed, followed by delusions (mostly delusions of persecution), dysphoria, and then agitation, and apathy. In contrast to the severity of amnesia, other cognitive functions were relatively spared, and the sensorimotor symptoms were not remarkable. CONCLUSIONS: AGD is a late-onset dementing disorder clinically characterized by amnesia, with other cognitive functions relatively spared, and prominent neuropsychiatric features. These features may correlate with the high level of AGD seen in limbic structures. Future studies are needed to elucidate whether these features are common to all AGD patients or to a clinical subtype with neuropsychiatric symptoms.     

Dementia with Lewy bodies]

"Dementia with Lewy bodies (DLB)" was proposed at the first international workshop in 1995. It has received much attention since we had proposed "Lewy body disease" in 1980 and "diffuse Lewy body disease" in 1984. In the CDLB guidelines, which were reported in 1996, the clinical and pathological diagnostic criteria for DLB were shown for the first time. At present, DLB as well as Alzheimer's disease (AD) and vascular dementia (VD) are known as the three major dementing illnesses. The second international workshop was held in 1998, and the third in 2003. One of the authors, K. Kosaka, presented a paper on DLB at each international workshop, based on series of our papers which we had reported since 1976. The revised CDLB guidelines will be reported soon. In addition, the fourth international workshop on DLB will be held by Kosaka in Yokohama in 2007. In this article, we review the history, the clinical, therapeutic, neuropathological, neurochemical and molecular biological issues, based on our previous papers and other important reports on DLB.     

Prolactin levels in schizophrenic patients receiving perospirone in comparison to risperidone

Serum prolactin levels were investigated in 41 patients with schizophrenia who were receiving clinically effective doses of perospirone or risperidone for more than 4 weeks. In order to determine baseline prolactin levels, blood samples were obtained in the morning, 10 - 14 h after antipsychotic medication. Median levels were within normal limits in both female and male patients receiving perospirone, while risperidone induced significant elevation. These results suggest that in contrast to risperidone, where baseline prolactin levels were elevated 5.3-fold in female and 4.2-fold in male patients, baseline prolactin levels are not elevated after treatment with perospirone. However, these results should be cautiously interpreted, because drug-by-time interaction has previously been reported in antipsychotic-induced hyperprolactinemia.     

Non‐uniformity in the regional pattern of Lewy pathology in brains of dementia with Lewy bodies

We examined the regional pattern of Lewy pathology in brains of dementia with Lewy bodies (DLB) to clarify whether Lewy pathology uniformly progresses or not. Thirty‐five autopsied DLB cases were examined using α‐synuclein‐immunohistochemistry, and the regional degree of Lewy pathology in the brainstem, diencephalon and cerebral cortex was quantitatively evaluated. Consequently, we found that the regional pattern of Lewy pathology differed according to the pathological subtype, and was divided into three types: type 1 showed a brainstem‐predominant pattern, type 2 was almost equal for the brainstem and cerebral cortex, and type 3 showed a cerebral cortex‐predominant pattern. The limbic type/pure and common forms were mainly composed of type 1, whereas the neocortical type/common and Alzheimer's disease (AD) forms were mainly composed of type 3. These findings suggest the possibility that Lewy pathology of the limbic type/pure and common forms mainly progresses from the brainstem to the cerebrum, whereas that of the neocortical type/common and AD forms mainly progresses from the cerebrum to the brainstem. Cases with type 1 Lewy pathology mainly developed parkinsonism, whereas those with type 3 Lewy pathology mainly developed dementia. This corresponded to most of the limbic type/pure and common forms which developed parkinsonism, whereas most of the neocortical type/common and AD forms developed dementia. Type 1 cases may thus be clinically diagnosed as having Parkinson's disease (PD) with dementia. These findings suggest that PD has clinico‐pathological continuity with DLB, and that the regional pattern of Lewy pathology is not uniform.     

Maintenance of paracellular barrier function by insulin-like growth factor-I in submandibular gland cells

Insulin-like growth factor-I (IGF-I) is expressed in salivary glands. We examined the effects of IGF-I on cell number, the expression and distribution of tight junction proteins and the paracellular barrier function in cells derived from rat submandibular glands. When those cells were cultured in medium containing 10% foetal bovine serum (FBS) or IGF-I, the number of cells was comparable at 10 days. However, in the presence of inhibitor of IGF-I receptors, the number of cells cultured with FBS only was clearly reduced. The tight junction proteins occludin and claudin-3 were similarly detected by Western blotting in cells cultured with IGF-I or FBS. Immunostaining revealed that occludin and another tight junction protein (ZO-1) were similarly localized at intracellular junctions of cells cultured with IGF-I or FBS. The barrier functions were evaluated by transepithelial resistance (TER) and by FITC-dextran permeability. The TER values and FITC-dextran permeability of cells cultured with IGF-I or FBS were comparable. These observations suggest that IGF-I contributes to the maintenance not only of the cell number of salivary gland cells but also of their paracellular barrier function via the expression and distribution of tight junction proteins.     

Distinct effects of CGRP on typical and atypical smooth muscle cells involved in generating spontaneous contractions in the mouse renal pelvis

Background and purpose:

We investigated the cellular mechanisms underlying spontaneous contractions in the mouse renal pelvis, regulated by calcitonin gene-related peptide (CGRP).

Experimental approach:

Spontaneous contractions, action potentials and Ca²⁺ transients in typical and atypical smooth muscle cells (TSMCs and ATSMCs) within the renal pelvis wall were recorded separately using tension and intracellular microelectrode recording techniques and Fluo-4 Ca²⁺ imaging. Immunohistochemical and electron microscopic studies were also carried out.

Key results:

Bundles of CGRP containing transient receptor potential cation channel, subfamily V, member 1-positive sensory nerves were situated near both TSMCs and ATSMCs. Nerve stimulation reduced the frequency but augmented the amplitude and duration of spontaneous phasic contractions, action potentials and Ca²⁺ transients in TSMCs. CGRP and agents increasing internal cyclic adenosine monophosphate (cAMP) mimicked the nerve-mediated modulation of TSMC activity and suppressed ATSMCs Ca²⁺ transients. Membrane hyperpolarization induced by CGRP or cAMP stimulators was blocked by glibenclamide, while their negative chronotropic effects were less affected. Glibenclamide enhanced TSMC Ca²⁺ transients but inhibited ATSMC Ca²⁺ transients, while both 5-hydroxydecanoate and diazoxide, a blocker and opener of mitochondrial ATP-sensitive K⁺ channels, respectively, reduced the Ca²⁺ transient frequency in both TSMCs and ATSMCs. Inhibition of mitochondrial function blocked ATSMCs Ca²⁺ transients and inhibited spontaneous excitation of TSMCs.

Conclusions and implications:

The negative chronotropic effects of CGRP result primarily from suppression of ATSMC Ca²⁺ transients rather than opening of plasmalemmal ATP-sensitive K⁺ channels in TSMCs. The positive inotropic effects of CGRP may derive from activation of TSMC L-type Ca²⁺ channels. Mitochondrial Ca²⁺ handling in ATSMCs also plays a critical role in generating Ca²⁺ transients.     

Muscarinic and 5-HT4 receptors participate in the regulation of the frequency of spontaneous contractions of the longitudinal muscle in rat distal colon

Spontaneous contractions of the intestine are thought to play an important role in the gastrointestinal motility, including peristalsis. In the present study, we investigated mechanisms for regulation of the frequency of spontaneous contractions, using longitudinal muscle strips in rat distal colon. Atropine significantly decreased the frequency of spontaneous contractions, indicating that neuromuscular transmission via muscarinic receptors increases the frequency of spontaneous contractions. SB-204070, 5-HT4 receptor antagonist also significantly decreased the frequency of spontaneous contractions, indicating that the activation of 5-HT4 receptors also increases the frequency of spontaneous contractions. In conclusion, it is suggested that muscarinic and 5-HT4 receptors participate in the regulation of the frequency of spontaneous contractions in the longitudinal muscle in rat distal colon, and that the frequency of spontaneous contraction is controlled by the enteric neurons.     

Localization of MAP1-LC3 in vulnerable neurons and Lewy bodies in brains of patients with dementia with Lewy bodies

There is emerging evidence implicating a role for the autophagy-lysosome pathway in the pathogenesis of Lewy body disease. We investigated potential neuropathologic and biochemical alterations of autophagy-lysosome pathway-related proteins in the brains of patients with dementia with Lewy bodies (DLB), Alzheimer disease (AD), and control subjects using antibodies against Ras-related protein Rab-7B (Rab7B), lysosomal-associated membrane protein 2 (LAMP2), and microtubule-associated protein 1A/1B light chain 3 (LC3). In DLB, but not in control brains, there were large Rab7B-immunoreactive endosomal granules. LC3 immunoreactivity was increased in vulnerable areas of DLB brains relative to that in control brains; computerized cell counting analysis revealed that LC3 levels were greater in the entorhinal cortex and amygdala of DLB brains than in controls. Rab7B levels were increased, and LAMP2 levels were decreased in the entorhinal cortex of DLB brains. In contrast, only a decrease in LAMP2 levels versus controls was found in AD brains. LC3 widely colocalized with several types of Lewy pathology; LAMP2 localized to the periphery or outside of brainstem-type Lewy bodies; Rab7B did not colocalize with Lewy pathology. Immunoblot analysis demonstrated specific accumulation of the autophagosomal LC3-II isoform in detergent-insoluble fractions from DLB brains. These results support apotential role for the autophagy-lysosome pathway in the pathogenesis of DLB.     

Neurofibrillary tangle-related synaptic alterations of spinal motor neurons of P301L tau transgenic mice

We investigated axosomatic synapses of anterior horn cells of transgenic (TG) mice expressing mutant P301L human tau and non-transgenic (NTG) mice using electron microscopic methods to demonstrate the relationship between neurofibrillary tangles (NFTs) and synaptic alterations. Animals aged 3.5-8.5 months were used because at this age many motor neurons in TG mice have NFTs. We measured the perimeter of anterior horn cell perikarya, the number of boutons and total length of boutons in contact with the neuronal perikarya from the micrographs of NFT and non-NFT-bearing neurons. We also calculated the proportion of the perimeter covered by boutons, density of boutons and mean size of boutons. The density of synaptic boutons in contact with NFT-bearing neurons was significantly decreased compared to non-NFT-bearing neurons. These findings suggest that synaptic reduction occurs during neurofibrillary degeneration and is probably associated with NFT. In addition, synaptic boutons were detached from NFT-bearing neurons with the resulting space occupied by astrocytic processes, suggesting that astrocytes may be involved in the observed synaptic alterations.