Building a 5-HT3A Receptor Expression Map in the Mouse Brain

Of the many serotonin receptors, the type 3 receptors (5-HT3R) are the only ionotropic ones, playing a key role in fast synaptic transmission and cognitive and emotional brain function through controlled neuronal excitation. To better understand the various functions of 5-HT3Rs, it is very important to know their expression pattern in the central nervous system (CNS). To date, many distributional studies have shown localized 5-HT3R expression in the brain and spinal cord. However, an accurate pattern of 5-HT3R expression in the CNS remains to be elucidated. To investigate the distribution of 5-HT3R in the mouse brain in detail, we performed immunofluorescent staining using 5-HT3AR-GFP transgenic mice. We found strong 5-HT3AR expression in the olfactory bulb, cerebral cortex, hippocampus, and amygdala; and partial expression in the pons, medulla, and spinal cord. Meanwhile, the thalamus, hypothalamus, and midbrain exhibited a few 5-HT3AR-expressing cells, and no expression was detected in the cerebellum. Further, double-immunostaining using neural markers confirmed that 5-HT3AR is expressed in GABAergic interneurons containing somatostatin or calretinin. In the present study, we built a 5-HT3AR expression map in the mouse brain. Our findings make significant contributions in elucidating the novel functions of 5-HT3R in the CNS.

14-3-3ζ-Mediated Stimulation of Oxidative Phosphorylation Exacerbates Oxidative Damage Under Hypothermic Oxygenated Conditions in Human Renal Tubular Cells (HK-2)

Cellular survival and death are at least partially regulated by the phosphorylation of proteins. A chaperon protein, 14-3-3ζ, regulates the activity of many proteins by covering the phosphorylation site within a 14-3-3 binding motif. Therefore, regulation of 14-3-3ζ activity may affect the fate of cells subjected to cold preservation and/or hypothermic oxygenated conditions. The present study assessed whether 14-3-3ζ protects cells from hypothermic oxygenation-induced injury and clarified its role in mitochondrial functions. Human renal tubular cell line HK-2 or 14-3-3ζ-overexpressed HK-2 (ζHK-2) cells were subjected to 72 hours of normoxic cold preservation in UW solution with or without antioxidants and hydroperoxides. Cellular death, adenosine triphosphate (ATP) content, and MTT catabolism were evaluated. Deferoxamine treatment reduced cellular death and augmented ATP content in both cell types. These indices were higher in ζHK-2, regardless of deferoxamine treatment. Exposure to hydroperoxides did not affect cellular death in either cell type, whereas hydroperoxide supplementation significantly reduced ATP content, except for low-dose hydrogen peroxide in HK-2 cells. MTT assay at normal state showed higher values in ζHK-2 cells, whereas it was impaired by hydroperoxides in both cell types. These results suggest that accumulation of hydroperoxides as a byproduct of the augmented oxidative phosphorylation by 14-3-3ζ overexpression causes mitochondrial dysfunction. In conclusion, despite possessing many potentially protective functions, 14-3-3ζ exacerbates cellular injury under hypothermic oxygenated conditions. 14-3-3ζ accelerates mitochondrial functions together with iron-dependent oxidative damage. Although further investigations are necessary, upregulation of 14-3-3ζ could be a method to maintain mitochondrial function under hypothermic oxygenated conditions, as shown in hypothermic machine preservation of renal grafts, when appropriate antioxidant treatment is administered.

Characterization by Electron Spin Resonance Spectroscopy of Reactive Oxygen Species Generated by Titanium Dioxide and Hydrogen Peroxide

The influence of reactive oxygen species (ROS) on the surface modification of titanium implants and osseointegration is unclear. The aim of this study was to evaluate the ability of titanium dioxide (TiO2) to generate ROS in the presence of H2O2 and to determine whether any ROS thus generated play a role in osseointegration, as measured by electron spin resonance (ESR) spin-trapping with 5,5-dimethyl-1-pyrolline- N-oxide (DMPO). We demonstrate that TiO2 together with H2O2 generated hydroxyl radicals (HO•), as shown by a time-dependent increase in the spin concentration of the ESR signal for the DMPO-OH spin adduct, indicating HO• generation. Interestingly, irradiated TiO2 with H2O2 generated the superoxide (O2•-), as shown by an increase in the spin concentration of the signal for the DMPO-OOH spin adduct, indicating O2•- generation during the period of irradiation (0–5 min). These results suggest that ROS generated from the TiO2 layer may be involved in creating appropriate conditions for the osseointegration of dental implants into alveolar bone tissues.

Functional Expression of an Osmosensitive Cation Channel, Transient Receptor Potential Vanilloid 4, in Rat Vestibular Ganglia

Transient receptor potential vanilloid (TRPV) 4 is a nonselective cation channel expressed in sensory neurons such as those in the dorsal root and trigeminal ganglia, kidney, and inner ear. TRPV4 is activated by mechanical stress, heat, low osmotic pressure, low pH, and phorbol derivatives such as 4α-phorbol 12,13-didecanoate (4α-PDD). We investigated the expression of TRPV4 in rat vestibular ganglion (VG) neurons. The TRPV4 gene was successfully amplified from VG neuron mRNA using reverse-transcription polymerase chain reaction. Furthermore, immunoblotting showed positive expression of TRPV4 protein in VG neurons. Immunohistochemistry indicated that TRPV4 was localized predominantly on the plasma membrane of VG neurons. Calcium (Ca2+) imaging of VG neurons showed that 4α-PDD and/or hypotonic stimuli caused an increase in intracellular Ca2+ concentration ([Ca2+]i) that was almost completely inhibited by ruthenium red, a selective antagonist of TRPV channels. Interestingly, a [Ca2+]i increase was evoked by both hypotonic stimuli and 4α-PDD in approximately 38% of VG neurons. These data indicate that TRPV4 is functionally expressed in VG neurons as an ion channel and that TRPV4 likely participates in VG neurons for vestibular neurotransmission as an osmoreceptor and/or mechanoreceptor.

Cisplatin-induced toxicity decreases the mouse vestibulo-ocular reflex

Cisplatin is a chemotherapeutic agent commonly used for the treatment of solid tumors, and its side-effects include vestibulotoxicity. Previous studies have reported cisplatin-induced vestibulotoxicity in various animal models, but no study has investigated in vivo mouse vestibular dysfunction after cisplatin. The aim of this study was to investigate cisplatin-induced vestibulotoxicity in C57BL/6J mice. Vestibular function was assessed by recording the vestibulo-ocular reflex (VOR). This was done during sinusoidal rotations in the horizontal plane at three frequencies (0.5, 1.0 and 2.5Hz). A high-resolution, high-frequency digital infra-red camera was used with eye-tracking algorithms. Cisplatin at 16mg/kg, but not 8mg/kg, decreased the VOR gain at 2.5Hz compared with the vehicle control. Following 16mg/kg cisplatin treatment, the animals showed no change in the optokinetic nystagmus response, suggesting that no major changes in visual or oculomotor functions had occurred. This mouse model may be useful for studying cisplatin-induced vestibulotoxicity and its treatment.

Urothelial ATP signaling: what is its role in bladder sensation?

AIM

Bladder functional disorders are common health problems; however, their pathologies are poorly understood. Adenosine triphosphate (ATP) released from the urothelium has been suggested to have an essential role in the micturition reflex, and its involvement in bladder functional disorders has been intensively investigated. Here, we review the latest advances in research on urothelial ATP signaling.

METHODS

We reviewed research articles on the role of the urothelium and urothelial ATP release in bladder function.

RESULTS

Mice lacking purinergic receptors have been reported to exhibit marked bladder hyporeflexia. Based on this observation, it was commonly believed, according to the widely held ATP urothelial signaling theory, that stretch-induced urothelial ATP release mediates the sensation of bladder filling via purinergic receptors. However, recent studies employing novel experimental methods and approaches have demonstrated that there are no significant differences in bladder function between wild-type and purinergic receptor knockout mice under physiological conditions. Nonetheless, under pathological conditions, inhibition of purinergic receptors has been shown to improve bladder hyperactivity. Moreover, enhanced urothelial ATP release has been reported in patients with bladder functional disorders.

CONCLUSIONS

Recently, conflicting evidence has led us to question the role of urothelial ATP signaling in normal micturition reflex. In contrast, under pathological conditions, it seems likely that enhanced urothelial ATP signaling mediates bladder hyperactivity. These recent findings suggest that the urothelial ATP signaling pathway is a potential therapeutic target for bladder functional disorders.

Donor Left-Sided Heptectomy by Use of the Real-Time Moving Windows Method With 8-Centimeter Transverse Skin Incision

BACKGROUND

In this study, we demonstrated our new device for open donor liver surgery with left-sided heptectomy by use of the real-time moving windows (RTMW) method with 8-cm transverse skin incision for living donors from the viewpoints of cosmetic, economic, and safety procedures.

METHODS

After the upper abdominal 8-cm transverse skin incision was made, the subcutaneous area was exfoliated and the reverse T-shaped-abdominal incision was made, as in open surgery. After that, the 2 Kent hooks for the upper region and the 2 surgical arms for the lower region were placed. The operative fields of hepatic vein, hepatic hilus, and common hepatic artery were explored, respectively, by use of the RTMW method with the use of the 4 surgical hooks. Hepatic parenchymal dissection was carried out with the use of CUSA and laparosonic coagulating shears. Manipulations of 3 hepatic vessels and the hepatic duct were done by the usual procedure of open surgery.

RESULTS

This operative procedure could be performed without laparoscopic techniques. The operative time was 7 hours, without blood transfusion. The operative course was uneventful, and the patient was discharged on postoperative day 11.

CONCLUSIONS

Our RTMW method for donor left-sided hepatectomy is considered to be a useful operative procedure from the viewpoints of donor safety, cosmetic advantage, and cost performance.

High-Speed Video-Oculography for Measuring Three-Dimensional Rotation Vectors of Eye Movements in Mice

Background

The mouse is the most commonly used animal model in biomedical research because of recent advances in molecular genetic techniques. Studies related to eye movement in mice are common in fields such as ophthalmology relating to vision, neuro-otology relating to the vestibulo-ocular reflex (VOR), neurology relating to the cerebellum’s role in movement, and psychology relating to attention. Recording eye movements in mice, however, is technically difficult.

Methods

We developed a new algorithm for analyzing the three-dimensional (3D) rotation vector of eye movement in mice using high-speed video-oculography (VOG). The algorithm made it possible to analyze the gain and phase of VOR using the eye’s angular velocity around the axis of eye rotation.

Results

When mice were rotated at 0.5 Hz and 2.5 Hz around the earth’s vertical axis with their heads in a 30° nose-down position, the vertical components of their left eye movements were in phase with the horizontal components. The VOR gain was 0.42 at 0.5 Hz and 0.74 at 2.5 Hz, and the phase lead of the eye movement against the turntable was 16.1° at 0.5 Hz and 4.88° at 2.5 Hz.

Conclusions

To the best of our knowledge, this is the first report of this algorithm being used to calculate a 3D rotation vector of eye movement in mice using high-speed VOG. We developed a technique for analyzing the 3D rotation vector of eye movements in mice with a high-speed infrared CCD camera. We concluded that the technique is suitable for analyzing eye movements in mice. We also include a C++ source code that can calculate the 3D rotation vectors of the eye position from two-dimensional coordinates of the pupil and the iris freckle in the image to this article.

Development and analysis of patient-derived xenograft mouse models in intravascular large B-cell lymphoma

Intravascular large B-cell lymphoma (IVLBCL) is a distinct disease entity with the peculiar characteristic that tumor cells proliferate within vessels. Despite recent advances in understanding the disease from clinical aspects, the underlying pathogenesis remains unknown. Here we demonstrate analyses of IVLBCL biology using four xenograft mouse models established from primary IVLBCL samples. In all four models, the main characteristic of IVLBCL tumor cell proliferation within vessels was retained. Time-lapse engraftment analyses revealed that the tumor cells initially engrafted and proliferated in the sinusoids and vessels in the liver and then engrafted and proliferated in multiple organs. Intriguingly, serial passage of tumor cells from the adrenal gland of a transplanted mouse developed from primary patient bone marrow cells into a second mouse showed that the tumor cells mainly distributed into the adrenal gland in the second mouse, implying the existence of clonal selection and/or evolution at engraftment of a specific organ. Gene expression profiling analyses demonstrated that the gene set associated with cell migration was enriched for normal peripheral blood B cells, indicating that inhibition of cell migration might be involved in IVLBCL pathogenesis. In conclusion, the mouse xenograft models described here are essential tools for uncovering IVLBCL biology.

Authentic role of ATP signaling in micturition reflex

Adenosine triphosphate (ATP) is a signaling molecule that regulates cellular processes. Based on previous studies of bladder function over the past decade, bladder ATP signaling was thought to have an essential role in the normal micturition reflex. In this study, we performed detailed analyses of bladder function in purinergic receptor-deficient mice using the automated voided stain on paper method and video-urodynamics. Unexpectedly, a lack of P2X₂ or P2X₃ receptors did not affect bladder function under normal physiological conditions, indicating that bladder ATP signaling is not essential for normal micturition reflex. In contrast, we found that lipopolysaccharide (LPS) induced markedly high levels of ATP release from the urothelium. In addition, LPS-induced rapid bladder hyperactivity was attenuated in P2X₂^−/− and P2X₃^−/− mice. Contrary to the previous interpretation, our present findings indicate that bladder ATP signaling has a fundamental role in the micturition reflex, especially in bladder dysfunction, under pathological conditions. Therefore, the bladder ATP signaling pathway might be a highly promising therapeutic target for functional bladder disorders. This study newly defines an authentic role for bladder ATP signaling in the micturition reflex.

Olefin hydrosilylation catalyzed by cationic nickel(ii) allyl complexes: a non-innocent allyl ligand-assisted mechanism

Cationic nickel allyl complexes catalyse selective monohydrosilylation of α-olefins with sec-silanes via a unique mechanism assisted by a non-innocent allyl ligand.

Serotonergic regulation of distention-induced ATP release from the urothelium

Serotonin [5-hydroxytryptamine (5-HT)] is involved in both motor and sensory functions in hollow organs, especially in the gastrointestinal tract. However, the involvement of 5-HT in visceral sensation of the urinary bladder remains unknown. Because distention-induced ATP release from the urothelium plays an essential role in visceral sensation of the urinary bladder, we investigated the regulation of urothelial ATP release by the 5-HT signaling system. RT-PCR and immunohistochemical analyses of the urothelium revealed specific expression of 5-HT_1D and 5-HT₄ receptors. The addition of 5-HT did not affect urothelial ATP release without bladder distention, but it significantly reduced distention-induced ATP release by physiological pressure during urine storage (5 cmH₂O). The inhibitory effect of 5-HT on distention-elicited ATP release was blocked by preincubation with the 5-HT_1B/1D antagonist GR-127935 but not by the 5-HT₄ antagonist SB-204070. mRNA encoding tryptophan hydroxylase 1 was detected in the urinary bladder by nested RT-PCR amplification, and l-tryptophan or the selective serotonin reuptake inhibitor citalopram also inhibited ATP release, indicating that 5-HT is endogenously synthesized and released in the urinary bladder. The addition of GR-127935 significantly enhanced the distention-elicited ATP release 40 min after distention, whereas SB-204070 reduced the amount of ATP release 20 min after distention. These data suggest that 5-HT₄ facilitates the distention-induced ATP release at an earlier stage, whereas 5-HT_1D inhibits ATP release at a later stage. The net inhibitory effect of 5-HT indicates that the action of 5-HT on the urothelium is mediated predominantly by 5-HT_1D.

The 5-HT3 receptor is essential for exercise-induced hippocampal neurogenesis and antidepressant effects

Exercise has a variety of beneficial effects on brain structure and function, such as hippocampal neurogenesis, mood and memory. Previous studies have shown that exercise enhances hippocampal neurogenesis, induces antidepressant effects and improves learning behavior. Brain serotonin (5-hydroxytryptamine, 5-HT) levels increase following exercise, and the 5-HT system has been suggested to have an important role in these exercise-induced neuronal effects. However, the precise mechanism remains unclear. In this study, analysis of the 5-HT type 3A receptor subunit-deficient (htr3a(-/-)) mice revealed that lack of the 5-HT type 3 (5-HT3) receptor resulted in loss of exercise-induced hippocampal neurogenesis and antidepressant effects, but not of learning enhancement. Furthermore, stimulation of the 5-HT3 receptor promoted neurogenesis. These findings demonstrate that the 5-HT3 receptor is the critical target of 5-HT action in the brain following exercise, and is indispensable for hippocampal neurogenesis and antidepressant effects induced by exercise. This is the first report of a pivotal 5-HT receptor subtype that has a fundamental role in exercise-induced morphological changes and psychological effects.