Osakabe, N. | Search bioRxiv

bioRxiv2025

Astringent flavanol fires the locus-noradrenergic system, regulating neurobehavior and autonomic nerves

Astringent flavanols (FLs) have shown enhanced cognitive function in a large intervention trial, but their mechanism remains unclear due to poor bioavailability. An oral dose of FLs increased spontaneous locomotion and memory, with activation of the sympathetic-adrenergic-medullary (SAM) and hypothalamic-pituitary-adrenal (HPA) axis, as shown by increased urinary catecholamine concentrations and corticotropin-releasing hormone (CRH) mRNA expression in the paraventricular nucleus (PVN) of mice. MS imaging showed high intensity of noradrenaline (NA) in the locus coeruleus (LC), which plays a key role in learning and memory, the hypothalamus lateral preoptic area, which affects sleep and arousal, and the brainstem as the origin of the sympathetic nervous system, immediately after FLs administration. Subsequent in situ hybridization (ISH) analysis showed that these NAs originated from LC. Astringent compounds like FLs influence brain function and physiological changes. Furthermore, the present series of results presents novel mechanisms by which food sensory properties maintain homeostasis. Highlights- A oral dose of astringent flavanols (FLs) immediately fires locus coeruleus-noradrenaline axis - FLs enhance spontaneous locomotion and short-term memory in mice - SAM and HPA axis are also activated by an oral dose of FLs - FLs astringency affects the brain and body, contributing to homeostasis.

synthetic biology↗

bioRxiv2018

Eldecalcitol is more effective for promoting osteogenesis than alfacalcidol in Cyp27b1-knockout Mice

Calcium (Ca) absorption from the intestinal tract is promoted by active vitamin D (1,25D3). Vitamin D not only promotes Ca homeostasis, but it also inhibits bone resorption and promotes osteogenesis, thus playing a role in the maintenance of normal bone metabolism. Because 1,25D3 plays an important role in osteogenesis, vitamin D formulations, such as alfacalcidol (ALF) and eldecalcitol (ELD), are used for treating osteoporosis. While it is known that, in contrast to ALF, ELD is an active ligand that directly acts on bone, the reason for its superior osteogenesis effects is unknown. Cyp27b1-knockout mice (Cyp27b1-/- mice) are congenitally deficient in 1,25D3 and exhibit marked hypocalcemia and high parathyroid hormone levels, resulting in osteodystrophy involving bone hypocalcification and growth plate cartilage hypertrophy. However, because the vitamin D receptor is expressed normally in Cyp27b1-/- mice, they respond normally to 1,25D3. Accordingly, in Cyp27b1-/- mice, the pharmacological effects of exogenously administered active vitamin D derivatives can be analyzed without being affected by 1,25D3. We used Cyp27b1-/- mice to characterize and clarify the superior osteogenic effects of ELD on the bone in comparison with ALF. The results indicated that compared to ALF, ELD strongly induces ECaC2, calbindin-D9k, and CYP24A1 in the duodenum, promoting Ca absorption and decreasing the plasma concentration of 1,25D3, resulting in improved osteogenesis. Because bone morphological measurements demonstrated that ELD has stronger effects on bone calcification, trabecular formation, and cancellous bone density than ALF, ELD appears to be a more effective therapeutic agent for treating postmenopausal osteoporosis, in which cancellous bone density decreases markedly. By using Cyp27b1-/- mice, this study was the first to succeed in clarifying the osteogenic effect of ELD without any influence of endogenous 1,25D3. Furthermore, ELD more strongly enhanced bone mineralization, trabecular proliferation, and cancellous bone density than did ALF. Thus, ELD is expected to show an effect on postmenopausal osteoporosis, in which cancellous bone mineral density decreases markedly.

biochemistry↗