Intestinal Calbindin Research Articles

Calcium Metabolism and Requirements of Chickens Are Affected by Growth

The interaction between growth and calcium homeostasis was studied by comparing the responses of (a) fast-growing broiler chickens (Cobb) and slow-growing Leghorns, and (b) fast-growing chickens (Cobb) fed either high energy (12.13 kJ/g) or low energy (9.2 kJ/g) diets, to dietary calcium concentration ranging between 4 and 20 g/kg). Plasma calcium increased as dietary calcium increased, reaching an apparent plateau between 0.8 and 1.5% dietary calcium, regardless of basal growth rate. Dietary calcium levels of 1.5% and higher induced hypercalcemia and hypophosphatemia in fast- but not in slow-growing chickens. Weight gain was unaffected by dietary calcium in the slow-growing Leghorns, but followed a bell-shaped response pattern in the fast-growing Cobb chickens. Growth inhibition by feeding of low energy diets changed the response pattern from a quadratic form to that of an increase towards a plateau. The response of bone ash to dietary calcium was characterized as quadratic in fast-growing chicks, changing to a pattern of increase towards a plateau in slow-growing chicks. Intestinal calbindin was suppressed by dietary calcium and was higher in the fast-growing than in the slow-growing chicks. An increase in dietary phosphorus resulted in a shift in the response curves of weight gain and bone ash and an increase in the calcium requirements. The results indicate that the response of chicks to dietary calcium and calcium requirements is markedly modified by growth rate.

Effect of dietary nonphytate phosphorus on laying performance and small intestinal epithelial phosphate transporter expression in Dwarf pink-shell laying hens

This study examined the effects of various levels of dietary nonphytate phosphorus on laying performance and the expression patterns of phosphorus metabolism related genes in Dwarf pink-shell laying hens. A total of 405 28-week-old Dwarf pink-shell laying hens were fed the same corn-soybean basal meals but containing 0.20%, 0.25%, 0.30%, 0.35% or 0.40% nonphytate phosphorus. The results showed that feed intake, egg production, and average egg weights were quadratically correlated with dietary nonphytate phosphorus content (P < 0.05), and the highest egg production, feed intake and average egg weights were achieved when dietary nonphytate phosphorus was at 0.3% (P < 0.05). mRNA expression of intestinal sodium phosphorus co-transporter linearly decreased when dietary nonphytate phosphorus increased. mRNA and protein expression of intestinal calbindin and vitamin D receptor correlated quadratically with dietary nonphytate phosphorus, and the highest expression was found when dietary available phosphorus was at 0.25% to 0.3%. In conclusion, the ideal phosphorus requirement for Dwarf pink-shell layer hens is estimated to be 0.3% in a corn-soybean diet. With this level of phosphorus supplementation, calbindin and vitamin D receptor reached their highest expression.

Villin promoter-mediated transgenic expression of transient receptor potential cation channel, subfamily V, member 6 (TRPV6) increases intestinal calcium absorption in wild-type and vitamin D receptor knockout mice.

Transient receptor potential cation channel, subfamily V, member 6 (TRPV6) is an apical membrane calcium (Ca) channel in the small intestine proposed to be essential for vitamin D-regulated intestinal Ca absorption. Recent studies have challenged the proposed role for TRPV6 in Ca absorption. We directly tested intestinal TRPV6 function in Ca and bone metabolism in wild-type (WT) and vitamin D receptor knockout (VDRKO) mice. TRPV6 transgenic mice (TG) were made with intestinal epithelium-specific expression of a 3X Flag-tagged human TRPV6 protein. TG and VDRKO mice were crossed to make TG-VDRKO mice. Ca and bone metabolism was examined in WT, TG, VDRKO, and TG-VDRKO mice. TG mice developed hypercalcemia and soft tissue calcification on a chow diet. In TG mice fed a 0.25% Ca diet, Ca absorption was more than three-fold higher and femur bone mineral density (BMD) was 26% higher than WT. Renal 1α hydroxylase (CYP27B1) mRNA and intestinal expression of the natural mouse TRPV6 gene were reduced to <10% of WT but small intestine calbindin-D(9k) expression was elevated >15 times in TG mice. TG-VDRKO mice had high Ca absorption that prevented the low serum Ca, high renal CYP27B1 mRNA, low BMD, and abnormal bone microarchitecture seen in VDRKO mice. In addition, small intestinal calbindin D(9K) mRNA and protein levels were elevated in TG-VDRKO. Transgenic TRPV6 expression in intestine is sufficient to increase Ca absorption and bone density, even in VDRKO mice. VDR-independent upregulation of intestinal calbindin D(9k) in TG-VDRKO suggests this protein may buffer intracellular Ca during Ca absorption. © 2012 American Society for Bone and Mineral Research.

Differential Regulation of Calbindin in the Calcium-Transporting Organs of Birds with High Calcium Requirements

The present review focuses on the differential regulation and differential expression, as well as the possible differential functionality, of avian calbindin-D28k in the three major calcium-transporting tissues: intestine, eggshell gland (ESG) and kidney. Special emphasis is given to their relationships with fast growth and with the laying of long clutches, i.e., unbroken sequences of eggs, separated by one or more days, as affected by the three major regulators, cholecalciferol (vitamin D3), gonadal activity, and intra- or extracellular calcium or its fluxes. The accumulated evidence suggests that intestinal calbindin mostly depends on vitamin D3, ESG calbindin appears to depend on calcium-transport-related factor (s) and to lesser extent also on gonadal activity; whereas renal calbindin partly depends on vitamin D3 and extracellular calcium.

Effect of age and dietary calcium on intestinal calbindin D-9k expression in the rat

The capacity of rats and humans to adapt to low dietary Ca by increasing intestinal Ca absorption declines with age. The intestinal calbindin-D-9k protein (calbindin) is thought to play a role in the transcellular transport of Ca across the mammalian intestine. The purpose of these studies was to determine the effect of age and diet on the expression of calbindin at the protein and mRNA levels. Young (2 month) and adult (12 month) male F344 rats were placed on either a high Ca diet (1.2%) or a low Ca diet (0.02%) for four weeks. In the duodenum, the level of intestinal calbindin protein induced by a low Ca diet was 8-fold higher in young rats compared to adult rats. In the ileum, expression of calbindin protein was only about 10% that of the duodenum. In addition, the adult ileum showed the same decreased adaptation to a low Ca diet that was seen in the adult duodenum. In both the duodenum and the ileum, the changes in calbindin protein expression were highly correlated with calbindin mRNA expression and the correlations in each segment were quantitatively similar. In the duodenum, the changes in calbindin protein levels were strongly correlated with both Ca transport and Ca uptake. This quantitative correlation suggests a role for calbindin protein in the age-related decline in Ca absorption. In the ileum, the decreased adaptation to a low Ca diet may also be important given the long transit time through the distal intestine. The changes in both intestinal segments may contribute to the negative Ca balance seen in adult rats fed a low Ca diet.

Aluminum Toxicity Alters the Regulation of Calbindin-D28k Protein and mRNA Expression in Chick Intestine

Previous studies have shown that aluminum inhibits vitamin D-dependent calcium absorption. The mechanism involves reduced sensitivity to 1,25-dihydroxycholecalciferol and reduced expression of the calcium transport protein, calbindin-D28k. Reduced expression of calbindin protein may be due to decreased levels of calbindin mRNA. To test this hypothesis, we measured calbindin mRNA levels in chicks fed diets with and without added aluminum. Groups of chicks were fed one of four diets: control, control plus aluminum, low calcium, or low calcium plus aluminum. A fifth group was fed a vitamin D-free diet as a negative control. Calbindin protein was measured by immunoblotting. Serum calcium and inorganic phosphorus were determined. Intestinal mRNA was isolated and assayed by slot-blot hybridization to a fluorescein-conjugated oligonucleotide probe complementary to calbindin-D28k mRNA. Antifluorescein antibodies conjugated to alkaline phosphatase were used to detect hybrids and mRNA levels were quantified by densitometry. Specificity of the probe was verified by Northern analysis. Intestinal calbindin protein was greater in the control plus aluminum group than in controls, but no difference in calbindin mRNA was observed. These changes were associated with small decreases in serum phosphorus and calcium, suggesting a postranscriptional effect of aluminum. Chicks fed the low calcium diet had greater intestinal calbindin protein and mRNA levels relative to the control group in association with a 45% decrease in serum calcium. In contrast, no difference in calbindin protein, and significantly less mRNA were found in the low calcium plus aluminum group compared with controls, despite a decrease in serum calcium similar to that of chicks fed the low calcium diet without aluminum. These results show that in chicks fed a low calcium diet, aluminum intake decreases transcription and/or stability of intestinal calbindin mRNA, and that aluminum may inhibit the expression of vitamin D-dependent genes.

Modeling of transcellular Ca transport in rat duodenum points to coexistence of two mechanisms of apical entry.

Employing realistic parameters, we have demonstrated that a relatively simple mathematical model can reproduce key features of steady-state Ca2+ transport with the assumption of two mechanisms of Ca2+ entry: a channel-like flux and a carrier-mediated transport. At low luminal [Ca2+] (1-5 mM), facilitated entry dominates and saturates with Km = 0.4 mM. At luminal [Ca2+] of tens of millimolar, apical permeability is dominated by the channel flux that in turn is regulated by cytosolic Ca2+. The model reproduces the linear relationship between maximum Ca2+ transport rate and intestinal calbindin D9K (CaBP) content. At luminal [Ca2+] > 50 mM, local sensitivity analysis shows transcellular transport to be most sensitive to variations in CaBP. At low luminal [Ca2+], transport becomes sensitive to apical entry regulation. The simulations have been run within the Virtual Cell modeling environment, yielding the time course of external Ca2+ and spatiotemporal distributions of both intracellular Ca2+ and CaBP. Coexistence of two apical entry mechanisms accords with the properties of the duodenal Ca2+ transport protein CaT1 and the epithelial Ca2+ channel ECaC.

Glutathione plays a role in the chick intestinal calcium absorption.

DL-buthionine-S,R-sulfoximine (BSO) administration to vitamin D-deficient chicks treated with cholecalciferol produces a rapid decrease in the Ca2+ transfer from lumen-to-plasma and in the intestinal glutathione content. This response was reversed by addition of glutathione monoester to the intestinal sac. Variables related to the Ca2+ homeostasis such as plasma Ca and P, and intestinal calbindin D28k were not modified by BSO given to vitamin D-deficient chicks treated with cholecalciferol. Intestinal alkaline phosphatase activity, on the contrary, was highly reduced by BSO in vitamin D-deficient chicks treated with vitamin D3. This effect showed time and dose-dependency. Although the mechanism/s of action of BSO on the intestinal Ca absorption is unknown, it is quite possible that thiol groups of protein involved in the Ca2+ transport are affected by the GSH depletion and/or by block of the antioxidant ability of vitamin D3. Thus, reactive oxygen compounds would be increased and, therefore, the Ca2+ movement from lumen to plasma decreases.

Dietary Aluminum Chloride Reduces the Amount of Intestinal Calbindin D-28K in Chicks Fed Low Calcium or Low Phosphorus Diets1–4

The mechanism of aluminum (Al) toxicity may involve disturbances in calcium (Ca) metabolism. Aluminum compounds have been reported to reduce vitamin D-dependent Ca absorption in chicks, rats and humans. To investigate the mechanism by which Al reduces Ca absorption, we studied the effect of dietary aluminum chloride (AlCl3) on the relative amounts of intestinal calbindin D-28K in chicks fed diets varying in Ca and phosphorus concentration. AlCl3 was added so that Al constituted 0, 0.15 or 0.3 g/100 g of diets that were either adequate, low in Ca, low in P, or contained supplemental P. Diets were fed for 2 wk. Intestinal calbindin D-28K levels were assayed using SDS-PAGE and 45Ca binding to Western blots. Added dietary Al greatly reduced the amount of intestinal calbindin in chicks fed adequate diets, low Ca diets, or low P diets. When diets with supplemental P were fed, little calbindin was evident with or without added Al. Tibia ash, body weight and food intake were also reduced (P < 0.05) by added Al. These results indicate that dietary AlCl3 inhibits vitamin D-dependent Ca absorption by reducing the amount of intestinal calbindin D-28K. Aluminum, therefore, may interfere with the body's ability to regulate intestinal calbindin D-28K levels. This could have implications for other tissues that contain substantial levels of calbindin D-28K.

1,25-Dihydroxycholecalciferol Supplementation Prevents Hypocalcemia in Magnesium-Deficient Chicks

To determine the relevance of circulating 1,25-dihydroxycholecalciferol [1,25(OH)2D3] to the pathogenesis of hypocalcemia during magnesium deficiency, growing chicks were pair fed control or Mg-deficient diets with or without 1,25(OH)2D3 supplementation. Within 14 d, chicks fed the Mg-deficient diet without 1,25(OH)2D3 supplementation exhibited hypomagnesemia and hypocalcemia compared to control chicks. 1,25-Dihydroxycholecalciferol supplementation in Mg-deficient chicks elevated plasma 1,25(OH)2D3 twofold and increased plasma calcium to control levels. Supplementation with 1,25(OH)2D3 did not increase plasma Mg concentration in Mg-deficient chicks, indicating that exogenous 1,25(OH)2D3 prevented hypocalcemia in the absence of greater Mg availability. Magnesium-deficient chicks supplemented with 1,25(OH)2D3 had more intestinal calbindin D-28K relative to Mg-deficient nonsupplemented chicks, suggesting that increased absorption of dietary Ca may have contributed to the greater plasma Ca concentration in 1,25(OH)2D3 supplemented Mg-deficient chicks. Although clinical hypomagnesemia has been associated with vitamin D resistance, our data indicate that primary Mg deficiency did not impair target tissue responsiveness to 1,25(OH)2D3, at least at the level of the intestine. Supplementation with 1,25(OH)2D3 did not increase bone Mg concentration and did not alter the characteristic skeletal morphology. It also did not increase bone Ca concentration in Mg-deficient chicks. The data suggest that skeletal alterations during Mg deficiency result from hypomagnesemia per se, rather than hypocalcemia or insufficient 1,25(OH)2D3.

Regulation of calbindin D 28K and its mRNA in the intestine of the domestic hen

Intestinal calbindin synthesis in laying hens was analyzed to assess controlling factors operating during egg formation. In the absence of vitamin D, calbindin was not induced by estrogen and testosterone. In immature vitamin D-replete pullet, blood levels of 1,25(OH) 2D 3 increased in response to estrogen but the duodenal concentration of calbindin and its mRNA were increased only when testosterone was given together with estrogen. The plasma concentration of 1,25(OH) 2D 3 and the duodenal levels of calbindin and its mRNA were substantially higher in laying hens than in immature pullets. No differences in these parameters were observed between the stages of the ovulatory cycle. Suppression of shell formation for a week decreased the concentration of 1,25(OH) 2D 3 and of duodenal calbindin but did not affect the level of its mRNA. When egg shell formation resumed in hens previously laying shell-less eggs, the concentrations of 1,25(OH) 2D 3 and of calbindin and its mRNA increased toward the end of shell formation. A most important factor regulating intestinal calbindin synthesis in laying hens turned out to be 1,25(OH) 2D 3. Intestinal calbindin mRNA is more stable in laying hens than in young birds as its concentration declines more slowly when the stimulation provided by 1,25(OH) 2D 3 is withdrawn, as occurs following suppression of shell formation and after parathyroidectomy in laying birds. Intestinal calbindin mRNA is therefore increased by a process other than increasing 1,25(OH) 2D 3 formation. The factor influencing the stability of this mRNA in laying hens could be calcium. It is concluded that in hens the increased duodenal calbindin synthesis elicited by plasma 1,25(OH) 2D 3 at sexual maturity primarily involves a transcriptional process and the stabilization of the mRNA. Shell formation further increases the calbindin concentration, possibly by more effective translation of the calbindin mRNA.

Modulation of quail intestinal and egg shell gland calbindin ( Mr 28,000) gene expression by vitamin D 3, 1,25-dihydroxyvitamin D 3 and egg laying

The effects of vitamin D 3 sources, egg production and egg cycle on the genomic expression of calbindin (M r 28,000) in the intestine and egg shell gland (ESG) of quail were characterized by Northern blot and solution hybridization, using synthetic oligonucleotide probe. In vitamin D 3- or 1,25-dihydroxyvitamin D 3 (1,25-(OH) 2D 3)-fed quail, onset of egg production induced duodenal and ESG calbindin mRNA and calbindin synthesis. Duodenal calbindin mRNA was slightly higher during the period of shell calcification as compared with the period during which shells were not formed (ESG inactivity). ESG calbindin mRNA was markedly higher during the period of shell calcification than of ESG inactivity. Increasing dietary intake of [ 3H]1α-hydroxyvitamin D 3 increased the duodenal, but not ESG, content of 1,25-(OH) 2D 3 and calbindin. Duodenal calbindin and its mRNA were absent in vitamin D-deficient quail and were not affected by egg laying. ESG calbindin in the vitamin D-deficient quail was not affected by egg laying, but calbindin mRNA increased in the vitamin D-deficient birds during shell calcification. The results suggest that: (a) intestinal calbindin mRNA and calbindin are induced and/or regulated, either directly or indirectly, by 1,25-(OH) 2D 3; (b) intestinal calbindin and its mRNA are further induced at the onset of egg laying by an additional stimulator besides 1,25-(OH) 2D 3; (c) 1,25-(OH) 2D 3 is required for the expression of the latter stimulator; (d) ESG calbindin mRNA and calbindin are induced in egg-laying birds by a stimulator associated with the egg cycle; and (e) the induction of ESG calbindin mRNA does not need vitamin D metabolites, but 1,25-(OH) 2D 3 is required for the translation of the mRNA.

Structure of the human brain calcium‐binding protein calretinin and its expression in bacteria

Calbindin D28k and calretinin are two closely related intracellular calcium-binding proteins belonging to the troponin C superfamily. Calbindin is known to be involved in the vitamin-D-dependent calcium absorption through intestinal and renal epithelia, while the function of neuronal calbindin and calretinin is poorly understood. Using antibodies directed against chick intestinal calbindin D28k, human calretinin cDNA clones were isolated from brain cDNA libraries. The sequence of the calretinin cDNA revealed an open reading frame of 271 codons coding for a protein of 31,520 Da, and sharing 58% identical residues with human calbindin D28k. Calretinin contains five presumably active and one presumably inactive calcium-binding domains. Comparison with the partial sequences available for chick and guinea pig calretinins revealed that the protein is highly conserved in evolution (evolutionary rate: 0.27 x 10(-9) amino acid-1 year-1). The calretinin message was detected in the brain, while absent from heart muscle, kidney, liver, lung, spleen, stomach and thyroid gland. Recombinant calretinin was expressed in Escherichia coli, and the calcium-binding properties were confirmed on both the natural and the recombinant proteins. Part of the human gene coding for calretinin was isolated and the region corresponding to the promoter and the first exon was sequenced.

Modulation of chick intestinal and renal calbindin gene expression by dietary vitamin D 3, 1,25-dihydroxyvitamin D 3, calcium and phosphorus

Synthetic oligonucleotide probes complementary to chick calbindin-28 kDa-mRNA were used to study the latter's regulation and relationship to calbindin in the chick. The effects of vitamin D 3 sources and dietary alteration on the genomic expression were characterized by Northern blot and solution hybridization. Intestinal calbindin and its mRNA were almost absent in vitamin D-deficient chicks and were not affected by dietary alteration. Renal calbindin and its mRNA were lower in the vitamin D-deficient than in vitamin D 3- or 1,25-dihydroxyvitamin D 3 (1,25(OH) 2D 3)-fed chicks. In the same animal, renal calbindin mRNA and calbindin were higher than intestinal. In vitamin D 3-fed chicks, dietary calcium (Ca) or phosphorus (P) restriction induced, and high dietary Ca inhibited, intestinal calbindin and its mRNA synthesis. In the same chicks, dietary P restriction induced renal calbindin mRNA and calbindin synthesis. In 1,25-(OH) 2D 3-fed chicks, dietary P restriction induced and high dietary Ca inhibited the synthesis of intestinal and renal calbindin. The results suggest that: (a) most of the changes in renal and intestinal calbindin could be attributed to the changes in the mRNA; (b) the adaptation to dietary Ca and P alterations requires vitamin D metabolites; (c) high dietary Ca affects intestinal and renal calbindin-mRNA and calbindin via mechanisms independent of kidney 1-hydroxylase; and (d) plasma Ca and renal calbindin or its mRNA tend to change together in vitamin D-deficient or vitamin D 3-fed, but not in 1,25(OH) 2D 3-fed chicks.

Poly‐ and Monoclonal Antibodies Against Recombinant Rat Brain Calbindin D‐28K Were Produced to Map Its Selective Distribution in the Central Nervous System

Many processes in the CNS depend on calcium. The calcium signal is transduced into an intracellular response via Ca2(+)-binding proteins, including calbindin D-28K. In many laboratories, polyclonal antibodies against chicken intestinal calbindin D-28K have been used to study its localization in the brain (normal and degenerated) of various species, including humans, but some of these antisera cross-reacted with other proteins, including calretinin. We purified recombinant rat brain calbindin D-28K to raise antisera in rabbits and purified a recombinant rat-chicken calbindin D-28K hybrid protein to immunize mice for the generation of monoclonal antibodies. These antisera were highly specific for calbindin D-28K, as demonstrated by two-dimensional Western blotting analysis. Immunohistochemical analyses combined with in situ hybridization studies demonstrated that calbindin D-28K in the Purkinje cells of the cerebellum is independent of vitamin D. The antibodies described here will be important tools for studying the regulation of expression of calbindin D-28K and its biological function in the brain and in the PNS.

Effect of dietary calcium and lead status on intestinal calcium absorption

Dietary lead intake was demonstrated to result in two very different effects on intestinal calcium absorption and associated parameters, depending on dietary calcium status. Normal growing 14-day-old chicks were fed diets either low (0.05%) or adequate (1.2%) in calcium and containing varying levels of lead (0%-0.8%) for an additional 10 days. In chicks fed the low calcium diet, ingested lead inhibited intestinal 47Ca absorption, and intestinal calbindin D and alkaline phosphatase synthesis in a dose-dependent fashion. Even at the highest levels of lead, however, this inhibition was limited to the stimulation of these parameters by low dietary calcium. In chicks fed the normal calcium diet, lead exposure did not diminish intestinal 47Ca absorption, or calbindin D or alkaline phosphatase synthesis, but actually elevated the values of these parameters at the higher lead exposure levels. The results indicate that the primary effect of lead, in both cases, occurs at or prior to intestinal protein synthesis and most likely involves the cholecalciferol endocrine system rather than any direct interactions between lead and calcium at the intestinal level.

Effect of Hormones and Development on the Expression of the Rat 1,25-Dihydroxyvitamin D3 Receptor Gene: Comparison with calbindin gene expression

We have used specific cDNAs to the rat vitamin D receptor (VDR) and to the mammalian vitamin D-dependent calcium-binding proteins (calbindin-D9k in intestine and calbindin-D28k in kidney) in order to obtain a better understanding of the regulation of the VDR gene and its relationship to calbindin gene expression. Hormonal regulation and development expression of the rat VDR gene were characterized by both Northern and slot blot analyses. Administration of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3; 25 ng/day for 7 days) to vitamin D-deficient rats resulted in an increase in calbindin mRNA in intestine and kidney but no change in VDR mRNA in these tissues. Vitamin D-deficient rats responded to dexamethasone treatment (100 micrograms/100 g of body weight/day for 4 days) with a 2.5-fold increase in intestinal VDR mRNA which was accompanied by a 4-fold decrease in intestinal calbindin-D9k mRNA. Developmental studies indicated a pronounced increase in renal VDR mRNA and calbindin-D28k mRNA between birth and 1 week of age. In the intestine, an induction of VDR and calbindin-D9k gene expression was observed at a later time, during the 3rd postnatal week (the period of increased duodenal active transport of calcium). Taken collectively, our data indicate that in the adult rat, target tissue response to hormone is not modified by a corresponding alteration in new receptor synthesis. However, developmental studies indicate that the induction of 1,25(OH)2D3 receptor mRNA is correlated with the induction of calbindin gene expression. Our results also demonstrate that glucocorticoid administration can result in an alteration in intestinal calbindin and VDR gene expression.

Vitamin D-dependent calcium binding proteins: chemistry, distribution, functional considerations, and molecular biology.

I. Forward One of the most important contributions to the vitamin D field has been the discovery by Wasserman and Taylor in 1966 (1) of vitamin D-dependent calcium binding protein [calbindin-D (2)]. Early studies using competitive ion exchange methods as well as equilibrium dialysis indicated that administration of vitamin D to rachitic chicks resulted in an increase in the calcium binding activity of crude extracts of intestinal mucosa (1). Further investigations showed that the calcium binding activity was associated with a protein of about 28,000 mol wt (3, 4). Soon after the discovery of avian intestinal calbindin (1), a vitamin D-responsive calcium binding protein was also shown to be present in rat intestine (5, 6). Since the initial discoveries of the avian and rat intestinal calbindins, calbindins have been reported in a variety of species (7–19) and in many other tissues including kidney (20–25), bone (26), and tissues which are not regulators of serum calcium such as pancreas (27–32), placenta (...

Calbindin immunoreactivity is a characteristic of enterochromaffin-like cells (ECL cells) of the human stomach.

Immunoreactivity for the calcium binding protein, calbindin D28k has been localized in enterochromaffin-like (ECL) cells of the human stomach. The reactivity was observed with three different antisera, raised against bovine brain, primate brain, and chicken intestinal calbindin. The ECL cells were closed endocrine cells located at the bases of the oxyntic glands. They were not found in other regions of the stomach. No other gastric endocrine cells were reactive with these antisera.

Loss of calbindin-28K immunoreactive neurones from the cortex in Alzheimer-type dementia

An antibody raised against chick intestinal calbindin D28K was used to study the number and size of calbindin immunoreactive neurones in postmortem human brains from neurologically normal controls and from patients with neuropathologically diagnosed Alzheimer-type dementia (ATD). In the controls, calbindin immunoreactive neurones were observed in all cerebral cortex areas examined including the frontal, temporal and parietal cortices. When compared with the controls, the number and size of calbindin immunoreactive neurones were significantly reduced in the cortices of patients with ATD. These findings suggest that calbindin containing neurones are affected in ATD.