Real-time monitoring of cortical brain activity in response to acute pain using wide-area Ca2+ imaging

Previous human and rodent studies indicated that nociceptive stimuli activate many brain regions that is involved in the somatosensory and emotional sensation. Although these studies have identified several important brain regions involved in pain perception, it has been a challenge to observe neural activity directly and simultaneously in these multiple brain regions during pain perception. Using a transgenic mouse expressing G-CaMP7 in majority of astrocytes and a subpopulation of excitatory neurons, we recorded the brain activity in the mouse cerebral cortex during acute pain stimulation. Both of hind paw pinch and intraplantar administration of formalin caused strong transient increase of the fluorescence in several cortical regions, including primary somatosensory, motor and retrosplenial cortex. This increase of the fluorescence intensity was attenuated by the pretreatment with morphine. The present study provides important insight into the cortico-cortical network during pain perception.

Phenotypes for general behavior, activity, and body temperature in 3q29 deletion model mice

Whole genome analysis has identified rare copy number variations (CNV) that are strongly involved in the pathogenesis of psychiatric disorders, and 3q29 deletion has been found to have the largest effect size. The 3q29 deletion mice model (3q29-del mice) has been established as a good pathological model for schizophrenia based on phenotypic analysis; however, circadian rhythm and sleep, which are also closely related to neuropsychiatric disorders, have not been investigated. In this study, our aims were to reevaluate the pathogenesis of 3q29-del by recreating model mice and analyzing their behavior and to identify novel new insights into the temporal activity and temperature fluctuations of the mouse model using a recently developed small implantable accelerometer chip, Nano-tag. We generated 3q29-del mice using genome editing technology and reevaluated common behavioral phenotypes. We next implanted Nano-tag in the abdominal cavity of mice for continuous measurements of long-time activity and body temperature. Our model mice exhibited weight loss similar to that of other mice reported previously. A general behavioral battery test in the model mice revealed phenotypes similar to those observed in mouse models of schizophrenia, including increased rearing frequency. Intraperitoneal implantation of Nano-tag, a miniature acceleration sensor, resulted in hypersensitive and rapid increases in the activity and body temperature of 3q29-del mice upon switching to lights-off condition. Similar to the 3q29-del mice reported previously, these mice are a promising model animals for schizophrenia. Successive quantitative analysis may provide results that could help in treating sleep disorders closely associated with neuropsychiatric disorders.

Visualization of Brain Activity in a Neuropathic Pain Model Using Quantitative Activity-Dependent Manganese Magnetic Resonance Imaging

Human brain imaging studies have revealed several regions that are activated in patients with chronic pain. In rodent brains, functional changes due to chronic pain have not been fully elucidated, as brain imaging techniques such as functional magnetic resonance imaging and positron emission tomography (PET) require the use of anesthesia to suppress movement. Consequently, conclusions derived from existing imaging studies in rodents may not accurately reflect brain activity under awake conditions. In this study, we used quantitative activation-induced manganese-enhanced magnetic resonance imaging to directly capture the previous brain activity of awake mice. We also observed and quantified the brain activity of the spared nerve injury (SNI) neuropathic pain model during awake conditions. SNI-operated mice exhibited a robust decrease of mechanical nociceptive threshold 14 days after nerve injury. Imaging on SNI-operated mice revealed increased neural activity in the limbic system and secondary somatosensory, sensory-motor, piriform, and insular cortex. We present the first study demonstrating a direct measurement of awake neural activity in a neuropathic pain mouse model.

Chronic brain blood-flow imaging device for a behavioral experiment using mice

A chronic brain blood-flow imaging device was developed for cerebrovascular disease treatment. This device comprises a small complementary metal-oxide semiconductor image sensor and a chronic fiber-optic plate window on a mouse head. A long-term cerebral blood-flow imaging technique was established in a freely moving mouse. Brain surface images were visible for one month using the chronic FOP window. This device obtained brain surface images and blood-flow velocity. The blood-flow changes were measured in behavioral experiments using this device. The chronic brain blood-flow imaging device may contribute to determining the cause of cerebrovascular disease and the development of cerebrovascular disease treatment.

Effect of Ninjin'yoeito on the Loss of Skeletal Muscle Function in Cancer-Bearing Mice

Ninjin'yoeito (NYT), a traditional Japanese Kampo medicine formula, is used as a remedy for conditions, and physical weakness. Cancer cachexia is seen in advanced cancer patients and is defined by an ongoing loss of skeletal-muscle mass that leads to progressive functional impairment. In the present study, we examined the hypothesis whether NYT improves the functional loss of skeletal muscle cancer cachexia. Male C57/BL 6J mice with B16BF6 melanoma tumor showed decreased expression of myosin heavy chain (MHC) in the gastrocnemius muscle. Moreover, the expression of SOCS3 and phosphorylated STAT3 and AMPK was increased, and the expression of phosphorylated 4E-BP1 was decreased in the gastrocnemius muscle of tumor-bearing mice. These data suggested that amino acid metabolism was altered in tumor-bearing mice, which were normalized by the NYT intervention. The present study showed that NYT might be a novel therapeutic option for the treatment of sarcopenia occurring cancer cachexia.