ABSTRACT Objective Epilepsy treatments often lead to vitamin D (VitD) deficiency. Although vitamin D₃ (VitD3) has been shown to reduce epileptic symptoms by 43%, its preventive effects remain unclear. This study investigated the potential of VitD pretreatment in two common acute epilepsy mouse models and explored its effects on seizure severity, latency, and molecular mechanisms involving calcium-sensing receptor (CaSR), phosphatase and tensin homolog (PTEN), and autophagy. Methods Mice were randomly divided into nine groups (n = 15). VitD or vehicle was administered 40 min before pentylenetetrazole (PTZ) or kainic acid (KA) given intraperitoneal injection (i.p). Seizure behavior and electroencephalograms (EEGs) were recorded for 60 min. After 24 h, hippocampal tissues were analyzed histologically and assessed for expression of autophagy-related proteins, CaSR, and PTEN. Results Both PTZ and KA induced acute seizures (Racine Grade IV+), with corresponding high-amplitude EEG spikes, neuronal damage, and mossy fiber sprouting. CaSR and autophagy markers were upregulated, while PTEN was downregulated, especially in the KA group. VitD pretreatment reduced seizure frequency, prolonged latency, alleviated hippocampal damage, downregulated CaSR and autophagy markers, and upregulated PTEN. These effects were milder than those of valproate. Combined VitD and Oroxin B treatment further improved outcomes. Conclusions (1) PTZ-induced seizures increased CaSR and decreased PTEN, triggering autophagy and worsening symptoms. (2) KA-induced epilepsy caused more severe damage with stronger autophagy activation. (3) VitD pretreatment mitigated seizures by modulating CaSR, PTEN, and autophagy, showing greater efficacy in the PTZ model.

Given the limited research on the use of water ionization devices for broiler chickens, this study aimed to explore the impact of ionized drinking water on their growth performance, oxidative status, and DNA damage. Six hundred one-day-old broiler chicks were randomly divided into two equal groups of six replicates (50 birds each). The control group (C) received tap water, and the treatment group (T) received ionized water. Water analysis for each treatment was performed. Productive traits, including water consumption and body weight, were recorded. Biochemical parameters, such as total protein, triiodothyronine (T3), total antioxidant capacity (TAC), and reactive oxygen species (ROS), were determined. Additionally, alkaline single-cell gel electrophoresis (SCGE) was performed to assess primary DNA damage. The results indicated that ionized water exhibited a negative oxidation-reduction potential (ORP), a characteristic often associated with antioxidant properties, and lower total dissolved solids (TDS) compared to tap water. The treated chicks showed higher water intake rates and final body weights than the control group. They also exhibited elevated levels of total protein, globulin, T3, TAC, and lower ROS levels than the control. Furthermore, the current results indicate that the use of ionized drinking water increases growth hormone (GH), insulin-like growth factor 1 (IGF-1), and aquaporin1 (AQP1) expression levels while decreasing calcium-sensing receptor (CaSR) and DNA damage. Consequently, the application of water ionization for broiler chicken drinking water is recommended to enhance animal productivity and health.

Large-scale high-throughput screen for cardiac ryanodine receptor targeted therapeutics.

Familial hypocalciuric hypercalcemia (FHH) is a genetically heterogeneous autosomal dominant disorder of calcium homeostasis, which is usually asymptomatic and characterized by low or normal phosphorus, inappropriately normal or elevated PTH, and low fractional excretion of calcium (FECa) in addition to hypercalcemia. Loss-of-function mutations in the G protein subunit alpha 11 (GNA11) gene, an important downstream signaling partner of the Calcium-sensing receptor (CaSR), cause FHH type 2. We reviewed the GNA11 gene-associated FHH type 2. A 14-year-old male was referred due to hypercalcemia (2.89 mmol/L). Slightly elevated PTH (7.95 pmol/L), but normal phosphorus (1.19 mmol/L), alkaline phosphatase (271 U/L), magnesium (0.95 mmol/L), and albumin (43 g/L) levels were detected. The FECa was found to be low when serum calcium was high (FECa was <0.01%, and <0.01% on two separate tests). A homozygous c.301T > C, p.Y101H variant was detected in the GNA11 gene. The same variant was detected heterozygous for both parents. While the calcium levels of the mother and father were normal, their spot urinary FECa was found low (Ca: 2.47 mmol/L, FECa: <0.01%, and Ca: 2.45 mmol/L, FECa: 0.01%, respectively). Hypocalciuria without hypercalcemia can be detected in cases heterozygous for the GNA11 gene mutation. Severe hypercalcemia may not occur in homozygous cases.

Abstract Background Familial Hypocalciuric Hypercalcemia (FHH) is a group of rare inherited diseases caused by loss-of-function mutations in the calcium-sensing receptor (CaSR) gene or related proteins. A significant link has not been discovered between germline inactivating CaSR mutations and parathyroid tumors in sporadic PHPT. However, it has been observed that most adenomatous and hyperplastic tumors have decreased CaSR expression. Case presentation A 59-year-old woman was referred to our clinic for evaluation of hypercalcemia despite having no active complaints. She underwent total thyroidectomy and parathyroidectomy due to parathyroid adenoma and multinodular goiter. Pathology revealed a parathyroid lipoadenoma. Postoperatively, calcium levels did not return to physiological ranges, raising suspicion of FHH. Genetic analysis identified compound heterozygosity for CASR c.665G &gt; A (p.Gly222Glu) and CASR c.2027 C &gt; G (p.Tyr676Arg) variants, confirming the diagnosis of FHH. Conclusion Co-existence of PHPT due to a parathyroid lipoadenoma and FHH is rare. Patients may still exhibit mild to moderate hypercalcemia following surgery, thus more invasive procedures should be avoided; failure of parathyroid exploration should not be assumed.

Glucagon-like peptide-1 (GLP-1) is a key metabolic hormone secreted by intestinal L-cells in response to nutrient ingestion. It plays a central role in regulating glucose homeostasis by enhancing insulin secretion, inhibiting glucagon release, delaying gastric emptying, and suppressing appetite. While glucose, fat, and protein are established stimulators of GLP-1 release, calcium has emerged as a key modulator of this enteroendocrine axis. Recent studies have shown that extracellular calcium, acting through the calcium-sensing receptor (CaSR) and voltage-gated calcium channels, triggers intracellular calcium influx, which is essential for GLP-1 exocytosis from L-cells. This highlights the role of calcium not merely as a dietary mineral but as a signaling ion that links nutrient sensing in the gastrointestinal tract to the hormonal regulation of blood glucose homeostasis. This chapter briefly explains how calcium influences the GLP-1-mediated gut-glucose axis.

The discovery of the bioactive constituents from herbal medicines remains a huge challenge in front of us. Here, a rapid approach was established by immobilizing full-length calcium sensing receptor (CaR) on the solid supports to screen the bioactive constituents from Epimedii Folium. The results indicated that the immobilized CaR can recognize specifically agonist Ca2+ as well as allosteric modulators cinacalcet and NPS2143, and the four bioactive compounds including epimedin A, epimedin B, epimedin C, and icariin were simultaneously screened from over 100 constituents in one injection of the Epimedii Folium extract. The chromatographic competitive binding experiment in combination with molecular docking gave the evidence that epimedin B and epimedin C were bound to the CaR's transmembrane domain whereas epimedin A and icariin interacted with the CaR's extracellular domain. These findings contributed to understanding the action mechanism of the four bioactive compounds with the CaR at the molecular level. Our work broke through the conventional way to isolate the interested molecules first and then testify their pharmacological and pharmacodynamic effects, establishing a rapid approach to discover simultaneously multiple active constituents from an herbal medicine.

Mandibular prognathism (MP) is the most common type of dentomaxillofacial deformity in East Asian populations. Genetic studies have revealed several MP-associated loci, suggesting that MP could be inherited as familial MP (fMP). However, functional verifications and in-depth mechanistic investigations of these loci are limited. For this study, we recruited 5 fMP families with 17 fMP members and 7 normal members. We first compared the clinical features of the 17 fMP members with 31 nonfamilial MP patients, finding a stronger mandibular overgrowth phenotype in the fMP subjects. Next, we performed whole-exome sequencing analysis with members of the 5 fMP families and singled out a potential fMP-associated pathogenic variant in the CASR gene (namely, rs117375173); the mutation introduces an amino acid substitution (A601G) in exon 7 and confers gain of function in Calcium-Sensing Receptor (CaSR). The rs11735173 variant changes the CaSR protein structure toward a semiactive state, similar to CaSR activated by L-tryptophan (L-Trp). To verify the regulating roles of CASR in mandibular bone growth, we further generated different mouse models with abnormal CaSR function. L-Trp administration effectively activated CaSR/GNAQ expression in vivo and in vitro. The MC3T3-E1 cell line transfected with CaSR with rs117375173 (CaSRA601G) showed increased osteogenic differentiation and collagen synthesis at the transcriptional level. Local injection of L-Trp in the mandible of growing mice significantly increased the mandibular length and BMD, due to activated osteogenic activity and suppressed bone resorption. At the same time, loss of function of CaSR in osteogenic progenitors caused mandibular growth retardation in Gli1-CreER; Casrfl/fl; tdTomatofl/+ mice. In conclusion, our study reveals that abnormal functioning of CaSR affects mandibular bone development and may contribute to the pathogenesis of fMP, providing a theoretical and experimental basis for the early diagnosis of and therapeutic strategies for fMP in clinical practice.

Both calcium-sensing receptor intracellular C-terminal domains support homodimer signaling.

Volatile medium-chain lactones function as taste modifiers, kokumi substances, by activating the calcium-sensing receptor in the oral cavity.

Insights into the effect and mechanism of low-bitterness porcine hemoglobin hydrolysates produced by γ-glutamyl transpeptidase.

Anti-urolithiatic potential of Pleurolobus gangeticus against calcium-sensing receptor and oxalate oxidase targets

Strontium and barium in deciduous teeth and infant feeding methods: A birth cohort adjunct study to the Japan environment and children's study.

Uncoupling toxic NO signaling: Progress, challenges, and therapeutic promise of disrupting the PSD-95/nNOS protein-protein interaction.

Calcium plays a central role in gastrointestinal (GI) physiology through regulating smooth muscle contractility, acid secretion, epithelial barrier integrity, and immune signaling. The dysregulation of calcium homeostasis has been increasingly implicated in the pathogenesis of GI disorders, including colorectal cancer, inflammatory bowel disease, peptic ulcer, and pancreatitis. Specifically, aberrant calcium-sensing receptor (CaSR) signaling has emerged as a critical molecular mechanism in colorectal tumorigenesis; meanwhile, calcium-mediated pathways influence gastric acid production and intestinal motility. This review critically evaluated recent advances in calcium signaling within the GI tract, highlighting the crosstalk involved with the gut microbiota and the roles of downstream effectors, including transient receptor potential vanilloid type 6 and store-operated calcium entry. This review also examined the therapeutic implications of calcium supplementation across various GI conditions, including bioavailability challenges under different disease states and nutrient interactions involving vitamin D and phosphate. Our review further addresses the role of calcium in mucosal immunity, the clinical relevance of hypocalcemia in GI diseases, and the potential of microbiome-guided nutritional interventions. However, despite growing mechanistic insights, considerable gaps remain in understanding host-microbiota-calcium interactions, genotype-specific responses to calcium, and long-term clinical outcomes. Thus, future research should clarify the dose-response relationships, stratify patient populations by CaSR polymorphisms and microbiome profiles, and establish precision strategies for calcium-based interventions in digestive health.

Familial hypocalciuric hypercalcemia (FHH) is a rare, usually benign, autosomal dominant disorder caused by mutations in the calcium-sensing receptor (CaSR) gene. It is typically characterized by mild, lifelong hypercalcemia, relative hypocalciuria, and normal or mildly elevated parathyroid hormone levels. Here we present a case of a 38-year-old male with newly diagnosed diabetes mellitus for 3 months who had recurrent episodes of acute pancreatitis for the last 1 year. Recurrent pancreatitis, a recognized complication of primary hyperparathyroidism, has rarely been reported on FHH, which made our case a unique one. Studying the case might help to develop insight into the diagnosis and management of this rare entity. [J Assoc Clin Endocrinol Diabetol Bangladesh, 2025;4(Suppl 1): S56]

Accurate quantification of calcium ions (Ca2+) in biologicalfluids is essential for elucidating cellular physiology and diagnosingcalcium-associated disorders, yet conventional analytical tools oftenface challenges, including limited sensitivity, interference fromcomplex matrices, and the need for large sample volumes. Here, wereport nanoengineered calcium receptors, Sens4Ca and Sens2Ca, integratedwith microscale thermophoresis (MST) to achieve sensitive, robustCa2+ detection using minimal sample volumes. The calciumreceptors are modular fusion proteins that combine calmodulin andcalmodulin-binding peptides with rigid structural domains to tailorbinding affinities and stoichiometries, enabling Ca2+ detectionacross nanomolar to micromolar concentrations. Unlike traditionalfluorescence-based assays, our MST platform monitors shifts in thermophoreticmobility, mitigating matrix interference and enhancing assay precision.We validate this approach for accurate Ca2+ quantificationin minimally processed biological and diagnostic samples, includingtumorigenic cells, tears, blood, and urine, demonstrating broad applicabilityunder diverse physiological conditions. This MST-based calcium sensingplatform offers a low-volume, interference-resistant approach forhigh-performance Ca2+ quantification, with broad potentialfor different disciplines ranging from fundamental biological researchto clinical diagnostics and environmental monitoring.

Human calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor (GPCR) that directly regulates parathyroid hormone release and maintains calcium homeostasis. The discovery of potent CaSR agonists with computer-aided drug design (CADD) has been appealing. Herein, we report the discovery of a series of new CaSR agonists by enhancing the molecular binding affinity through the replacement of key residues via the iCVETide platform. Ac-D-Cys(L-Cys)-D-Arg-D-(3-Gu)-Phe-D-Abu-D-Arg-D-Ala-D-Arg-NH2 (compound 6g) with an outstanding activity and a satisfactory ADME profile is discovered, and the interaction mode between 6g and CaSR is elucidated through molecular docking and molecular dynamics simulations, showing hydrogen bonds, salt bridges, and π-π stacking. In addition, 6g is capable of activating human CaSR as a calcimimetic positive allosteric modulator. Our results provide a viable alternative to approved calcimimetics and a novel protocol for the discovery of CaSR agonists.

Disclosure: A.D. Conigrave: None. M.A. Goolam: None. Q. Fan: None. D.T. Ward: None. S.J. Simpson: None.The calcium-sensing receptor (CaSR) is critical for calcium homeostasis by mediating calcium-stimulated inhibition of PTH secretion and promotion of renal calcium excretion. In a second major endocrine action, the CaSR is required for L-amino acid stimulated release of gastrointestinal hormones including GLP-1, GIP and PYY, with impacts on insulin release and postprandial blood glucose levels, and also energy intake. Amino acids (AAs) and calcium (Ca2+) interact mutually via linked CaSR binding sites to promote potency (AAs on Ca2+) and efficacy (Ca2+ on AAs), supporting interactions between calcium and amino acids upon the digestion of complex foods. Previous work has demonstrated that AAs robustly raise intracellular Ca2+ levels(1) and either stimulate (GLP-1, GIP, PYY (2)) or inhibit (PTH (3)) hormone secretion. Surprisingly, AAs have been reported to have no effect on accumulation of the inositol phosphate IP1 which, like Ca2+ mobilization, measures receptor-dependent activation of Gq/11 and PI-PLC. In the present study we hypothesized that autocrine production and release of local activators of the CaSR AA binding site might compete with exogenous AAs in static cell culture-based assays but not in assays in which cells are continuously perifused. In static cultures we found that washing cultured HEK-293 cells that were stably transfected with the CaSR with fresh AA-free medium markedly reduced Ca2+ sensitivity and exposed AA stimulation of IP1 accumulation. Since glutathione has been reported to stimulate the CaSR via the AA binding site(4), we also tested whether inhibition of glutathione synthesis with buthionine sulfoximine might expose AA stimulated IP1 accumulation. The effects of BSO treatment exceeded those of concerted washing.We conclude that the effects of AAs in CaSR expressing cells are dependent on the following factors: (i) Ca2+ concentration; (ii) AA concentration; (iii) local release of competing autocrine activators; (iv) the rate of exchange with systemic plasma. 1. Proc Natl Acad Sci USA. 2000;97:4814-92. J Physiol. 2012;590:2917-363. J Biol Chem. 2004;279:38151-94. J Biol Chem. 2011;286:8786-97Presentation: Sunday, July 13, 2025

Disclosure: L.I. Guerrero Arroyo: None. A.R. Gonciulea: None. S.K. Majumdar: None.Introduction: Familial Hypocalciuric Hypercalcemia (FHH) is an autosomal dominant condition characterized by hypercalcemia, relative hypocalciuria, and non-suppressed parathyroid hormone (PTH) levels, resulting from inactivating mutations in the CASR and associated genes. FHH usually follows a benign course and does not require surgical treatment but occasionally its features overlap with primary hyperparathyroidism (PHPT) making diagnosis and clinical management challenging. We describe three family members harboring a heterozygous variant in the CASR gene associated with FHH in whom calcium levels appear to increase with successive generations and two of whom have kidney stones and osteopenia. Case: Three women from successive generations of the same family were evaluated for hypercalcemia. They presented at ages 60, grandmother (G), 47, mother (M), and 17, daughter (D). Clinical follow up has been available for 10, 13, and 5 years, respectively for G, M, and D. The following laboratory results are notable during follow up (ranges for G, M, D): Calcium (mg/dL) 9.6-11.9, 8.8-12.4, and 11.4-12.5, Phosphorus (mg/dL) 2.5-2.6, 1.1-3.5, 2.4-2.8, Magnesium (mg/dL) 1.9-2.1, 1.5-2.4, 2.2-2.4, PTH (pg/mL) 88-122, 49-118, 34.8-102, 24h urine calcium (mg) 166, 60-248, 93-270, and calcium to creatinine clearance ratios of 0.009, 0.006, and 0.006. Bone density testing (Hologic) revealed a femoral neck (FN) T score of -2.1 at age 67 (G) and FN -1.3, spine -2.4 and distal radius -0.5 (T scores) in the daughter (age 49). G and M both have kidney stones documented on imaging studies and M had a 4D-CT of the neck with equivocal findings suggestive of 2 enlarged parathyroid glands. G had no imaging, and D had a negative parathyroid ultrasound. Genetic testing was performed to differentiate between FHH and PHPT which revealed a heterozygous pathogenic variant in the CASR gene in each patient: NM_000388:exon4:c.C658T:p. R220W (chr3:121980540) [hg19]. Discussion: PHPT and FHH are important to consider in the differential diagnosis of hypercalcemia with non-suppressed PTH since their management approaches differ, making it essential to differentiate between these conditions. We report a family with a R220W variant in the CASR gene in whom some members have features that overlap between PHPT and FHH. The variability in urine calcium, presence of kidney stones and low bone density, and successive generational increase in serum calcium may be features of the R220W variant. It is possible that our patients have independent genetic or sporadic risks for bone loss and kidney stones and the overall benefit of medical or surgical intervention remains uncertain.Presentation: Monday, July 14, 2025