👤 Wayne Lok

Intrinsic Capacity (IC) is defined as the composite of physical and mental abilities an individual possesses, encompassing five domains: cognition, psychological health, sensory function, vitality, and locomotion. This construct is central to the World Health Organization's framework for assessing functional ability in older adults. Growing evidence highlights the critical role of the musculoskeletal system in maintaining these domains, while conditions such as sarcopenia, osteoporosis, and their coexistence as osteosarcopenia (OS) are increasingly associated with IC decline. This narrative review compiles current evidence on the modulatory role of muscles and bones in IC and the impacts of sarcopenia, osteoporosis, and OS. Most findings suggest that musculoskeletal tissues influence IC not only through biomechanical functions but also as secretory organs, releasing myokines and osteokines with endocrine, paracrine, and autocrine effects. Among the most studied are brain-derived neurotrophic factor, irisin, osteocalcin, and interleukin-6. Dysregulation of these pathways, along with biomechanical dysfunction and systemic inflammation, links sarcopenia, osteoporosis, and OS to IC impairment. Further research is needed to clarify the specific mechanisms involved, particularly in the sensory and vitality domains, to inform targeted interventions that promote healthy aging. Show less

Despite available therapies for depression, many patients do not achieve adequate improvement, illustrating the need for innovative treatment strategies. Nutritional psychiatry is an emerging area, with increasing evidence that microbially derived butyrate contributes to the beneficial effects of dietary, pre-, pro- and synbiotics interventions - raising the exciting possibility that direct butyrate administration might alleviate depressive symptoms. The main objective was to systematically review the effects of butyrate on depressive symptoms in humans and depressive-like behavior in animals (PROSPERO; CRD42023g0739). A search was conducted in MEDLINE, Embase, PsycINFO, and Web of Science, ICTPR and ClinicalTrials.gov up to October 2025. Studies were included if they examined depressive symptoms in humans or relevant behaviors in animal models of depression/anxiety, involved treatment with butyrate formulations, included a control or pre-post comparison, and reported behavioral or clinical outcomes. Eligible designs included case-control, cohort, (randomized) controlled trials, experimental, or in vivo studies published in English or Dutch. Studies were excluded if depression was not the primary focus or if butyrate was combined with another treatment. Risk of bias was assessed with SYRCLE for animal studies and RoB 2 for the human studies. Of the two randomized controlled trials, one found no measurable effect of 1-week oral butyrate in healthy males, whereas the other found reductions in depressive and anxiety symptoms in patients with ulcerative colitis after 12-weeks oral butyrate. Thirty-two animal studies showed that butyrate generally modulated depressive- and anxiety-like phenotypes in rodents, potentially via anti-inflammatory, neuroplastic, epigenetic and gut-mediated mechanisms. Preclinical findings support the therapeutic promise of butyrate as a novel intervention for depression, warranting further clinical investigation. BDNF, Brain-derived neurotrophic factor; CRS, Chronic restraint stress; CSD, Chronic social defeat; CUMS, Chronic unpredictable mild stress; DASS, Depression, anxiety, Stress Scales; EPM, Elevated plus maze; FMT, Fecal microbiota transplant; FST, Forced swim test; HDAC, Histone deacetylase; HFD, High-fat diet; HPA, Hypothalamic-pituitary-adrenal; ICTRP International Clinical Trials Registry Platform; IL, Interleukin; LDB, Light-dark box; LEIDS-R, Leiden Index of Depression Severity-Revised; LPS, Lipopolysaccharide; MD, Maternal deprivation; MDD, Major depressive disorder; MGBA, Microbiota-gut-brain axis; NORT, Novel object recognition test; OFT, Open field test; PFC, Prefrontal cortex; PRISMA Preferred reporting items for systematic reviews and meta-analyses; SCFA, Short-chain fatty acid; SPT, Sucrose preference test; SYRCLE, Systematic Review Centre for Laboratory Animal Experimentation; TCA, Tricarboxylic acid; TNF, Tumor necrosis factor; TST, Tail suspension test; ZO-1, Zonulin-1. Show less

Pituitary adenylate cyclase-activating peptide (PACAP) receptor (PAC1R) is a class B Gprotein-coupled receptor (GPCR) that is widely expressed in the human body and is involved in neuronal differentiation. As class B GPCRs are known to form heterocomplexes with family members, we hypothesized that PAC1R mediates neuronal differentiation through interaction with a class B GPCR. We used the BRET assay to identify potential interactions between PAC1R and 11 class B GPCRs. Gastric inhibitory polypeptide receptor (GIPR) and secretin receptor were identified as putative binding partners of PAC1R. The effect of heterocomplex formation by PAC1R on receptor activation was evaluated with the cyclic (c)AMP, luciferase reporter, and calcium signaling assays; and the effects on receptor internalization and subcellular localization were examined by confocal microscopy. The results suggested he PAC1R/GIPR heterocomplex suppressed signaling events downstream of PAC1R, including cAMP production, serum response element and calcium signaling, and β-arrestin recruitment. Protein-protein interaction was analyzed in silico, and induction of neuronal differentiation by the PAC1R heterocomplex was assessed in SH-SY5Y neuronal cells by measure the morphological changes and marker genes expression by real-time quantitative PCR and western blot. Over-expression of GIPR suppressed PACAP/PAC1R-mediated neuronal differentiation and the differentiation markers expression in SH-SY5Y cells. GIPR regulates neuronal differentiation through heterocomplex formation with PAC1R. Show less