👤 Takuya Omura

Cerebral small vessel disease (SVD) is prevalent in older adults with type 2 diabetes and contributes to an elevated risk of cognitive decline. Although physical activity (PA) is a potentially modifiable factor in SVD prevention, previous findings remain inconsistent, particularly regarding activity intensity. This study aimed to investigate the association between accelerometer-measured PA and SVD severity in older adults with type 2 diabetes. This cross-sectional study analyzed 66 adults aged ≥70 years with type 2 diabetes. PA was objectively measured using a tri-axial accelerometer over 14 days. Time spent in sedentary behavior (≤1.5 metabolic equivalents [METs]), light-intensity PA (LPA; 1.6-2.9 METs), and moderate-to-vigorous PA (MVPA; ≥3.0 METs) were assessed. Lacunes, cerebral microbleeds, enlarged perivascular spaces, and white matter hyperintensities were evaluated using brain magnetic resonance imaging. The total SVD score (range, 0-4) was calculated, and participants were categorized into either mild (score 0-1) or moderate-to-severe (score 2-4) groups. To estimate the odds of having moderate-to-severe SVD associated with a hypothetical reallocation of 10 min of sedentary time to either LPA or MVPA, multiple logistic regression analysis using an isotemporal substitution model was performed. Of the 66 participants, 29 (43.9%) had moderate-to-severe SVD. A hypothetical reallocation of 10 min from sedentary time to MVPA was associated with lower odds of moderate-to-severe SVD (odds ratio, 0.78; 95% confidence interval, 0.61-1.00; p = 0.047). LPA exhibited no significant association. Engaging in MVPA is associated with lower SVD severity in older adults with type 2 diabetes. Show less

Chemoreception in the mouse olfactory system occurs primarily at two chemosensory epithelia in the nasal cavity: the main olfactory epithelium (MOE) and the vomeronasal epithelium. The canonical chemosensory neurons in the MOE, the olfactory sensory neurons (OSNs), express the odorant receptor (OR) gene repertoire, and depend on Adcy3 and Cnga2 for chemosensory signal transduction. The canonical chemosensory neurons in the vomeronasal epithelium, the vomeronasal sensory neurons (VSNs), express two unrelated vomeronasal receptor (VR) gene repertoires, and involve Trpc2 for chemosensory signal transduction. Recently we reported the discovery of two types of neurons in the mouse MOE that express Trcp2 in addition to Cnga2. These cell types can be distinguished at the single-cell level by expression of Adcy3: positive, type A and negative, type B. Some type A cells express OR genes. Thus far there is no specific gene or marker for type B cells, hampering further analyses such as physiological recordings. Here, we show that among MOE cells, type B cells are unique in their expression of the soluble guanylate cyclase Gucy1b2. We came across Gucy1b2 in an explorative approach based on Long Serial Analysis of Gene Expression (LongSAGE) that we applied to single red-fluorescent cells isolated from whole olfactory mucosa and vomeronasal organ of mice of a novel Trcp2-IRES-taumCherry gene-targeted strain. The generation of a novel Gucy1b2-IRES-tauGFP gene-targeted strain enabled us to visualize coalescence of axons of type B cells into glomeruli in the main olfactory bulb. Our molecular and anatomical analyses define Gucy1b2 as a marker for type B cells within the MOE. The Gucy1b2-IRES-tauGFP strain will be useful for physiological, molecular, cellular, and anatomical studies of this newly described chemosensory subsystem. Show less

The mouse olfactory system contains two distinct chemosensory epithelia, the main olfactory epithelium (MOE) and the vomeronasal epithelium (VNE). Their sensory neurons express odorant receptor genes and vomeronasal receptor genes, respectively, and differ fundamentally in their signal transduction pathways. Genes required for chemosensory transduction are the cyclic nucleotide-gated channel subunit Cnga2 and the transient receptor potential cation channel Trpc2, respectively. Here, we document two previously unrecognized types of Trpc2+ neurons in the MOE of mice of various ages, including adults. These cell types express Cnga2 and can be distinguished by expression of adenylate cyclase Adcy3 (positive: type A; negative: type B). A third of MOE neurons that express the odorant receptor genes Olfr68/Olfr69 coexpress Trpc2 and are type A cells. In Trpc2-IRES-taulacZ gene-targeted mice, some labeled axons coalesce into glomeruli in the main olfactory bulb. Our findings have implications for the conventional VNE-centric interpretation of the behavioral phenotypes of Trpc2 knockout mice. Show less