Calbindin D28k Research Articles

Changes in the distribution of calbindin D28-k, parvalbumin, and calretinin in the hippocampus of the circling mouse

The circling (cir) mouse strain, a murine model of deafness caused by a spontaneous mutation, exhibits characteristic behaviors of circling and hyperactivity. In an induced-noise paradigm, cir mice display a significant loss in their spatial orientation abilities, and this has been suggested to be due at least in part to changes in calcium homeostasis. Auditory information is transferred from the cochlear nucleus to the hippocampus, where it is processed to modulate motor and sensory activity. Such a pathway could be affected at the cellular level by alterations in neurotransmission, including alterations that involve Ca2+. However, there have been no studies in a hearing deficit model examining the concomitant molecular alterations in the hippocampus. Thus, in the present study we used immunohistochemistry to compare the distribution of the calcium-binding proteins (CaBPs) calbindin D-28k, parvalbumin, and calretinin in the hippocampi of heterozygous (+/cir), homozygous (cir/cir), and wild-type (+/+) mice. The expression of the CaBPs in various hippocampal subfields appeared to be significantly lower in cir mice (+/− and −/−) than in +/+ mice. Such a decrease in CaBP expression in cir/cir mice would alter calcium homeostasis, which in turn could affect the connection of the tri-synaptic circuit of the hippocampus as well as the cortical region. A decrease in CaBPs and the probable resultant glutamate-mediated excitability could contribute to the functional changes that lead to the characteristic behavioral features of cir mice.

Participation of calbindin-D28K in nociception: results from calbindin-D28K knockout mice

Since calbindin-D(28K) (CB-D(28K))-positive neurons have been related to nociceptive sensory processing, we have hypothesized that altered CB-D(28K) expression could alter nociceptive transmission. We have used +/+ and -/- knockout (KO) mice for CB-D(28k) in different behavioral models of pain and sensory responses at the caudalis subdivision of the trigeminal spinal nucleus in order to understand how this protein may participate in nociception. Behavioral responses to formalin injection in the hind paw or at the whisker pad or in the hind paw glutamate or i.p. acetic acid tests showed an increase of the pain threshold in CB-D(28k) -/- mice. KO mice showed a diminution of the inhibitory activity at Sp5C nucleus and a marked reduction of GABA content. Sp5C neurons from CB-D(28k) -/- mice did not change their spontaneous activity or tactile response after formalin injection in the whisker pad. In contrast, Sp5C neurons increased their spontaneous firing rate and tactile response after formalin injection in their receptive field in CB-D(28k) +/+ mice. The results of this study demonstrate the active role played by CB-D(28k) in nociceptive sensory transmission. The lack of this calcium binding protein, associated to deficient GABAergic neurotransmission, translates into dysfunction of sensory processing of nociceptive stimuli.

Peptide 19-containing neurons in the medullary dorsal horn, subnuclei interpolaris and oralis, and nucleus principalis of the rat

Peptide 19 (PEP 19) is a 7.6 kDa polypeptide which can bind to calmodulin and inhibit calcium-calmodulin signaling. In this study, PEP 19-immunoreactivity (ir) was examined in the rat trigeminal sensory nuclei. Numerous PEP 19-immunoreactive (ir) neurons were detected in the medullary dorsal horn (MDH) and rostral parts of the trigeminal sensory nuclei (subnuclei interpolaris and oralis, and nucleus principalis). The mean numbers ± S.D. per section of PEP 19-ir neurons were 104.2 ± 30.4 in the MDH, 137.8 ± 39.5 in the subnucleus interpolaris, 129.2 ± 46.9 in the subnucleus oralis and 157.2 ± 34.1 in the nucleus principalis. In the MDH, small to medium-sized PEP 19-ir neurons were abundant within superficial laminae. PEP 19-ir neurons with various cell body sizes were also distributed in the rostral parts of the trigeminal sensory nuclei. A double immunofluorescence analysis also demonstrated that many PEP 19-ir neurons co-expressed parvalbumin (PV)-ir in the MDH (9.0%), subnucleus oralis (7.7%) and nucleus principalis (19.7%). In the subnucleus interpolaris, such neurons were relatively rare (1.7%). PEP 19-ir neurons were mostly devoid of calbindin D-28k. In addition, a retrograde tracing method revealed that a substantial number of PEP 19-ir neurons projected to the thalamus. PV-ir was common in thalamus-projecting PEP 19-ir neurons. These findings suggest that PEP 19-ir neurons in the MDH may have a function in modulation of nociceptive and thermo-receptive signaling. It is also likely that PEP 19-ir neurons in rostral parts of the trigeminal sensory nuclei are related to transduction of mechano-receptive information from facial regions to the thalamus.

Calcium-binding proteins and GFAP immunoreactivity alterations in murine hippocampus after 1 month of exposure to 835 MHz radiofrequency at SAR values of 1.6 and 4.0 W/kg

Widespread use of wireless mobile communication has raised concerns of adverse effect to the brain owing to the proximity during use due to the electromagnetic field emitted by mobile phones. Changes in calcium ion concentrations via binding proteins can disturb calcium homeostasis; however, the correlation between calcium-binding protein (CaBP) immunoreactivity (IR) and glial cells has not been determined with different SAR values. Different SAR values [1.6 (E1.6 group) and 4.0 (E4 group) W/kg] were applied to determine the distribution of calbindin D28-k (CB), calretinin (CR), and glial fibrillary acidic protein (GFAP) IR in murine hippocampus. Compared with sham control group, decreased CB and CR IRs, loss of CB and CR immunoreactive cells and increased GFAP IR exhibiting hypertrophic cytoplasmic processes were noted in both experimental groups. E4 group showed a prominent decrement in CB and CR IR than the E1.6 group due to down-regulation of CaBP proteins and neuronal loss. GFAP IR was more prominent in the E4 group than the E1.6 group. Decrement in the CaBPs can affect the calcium-buffering capacity leading to cell death, while increased GFAP IR and changes in astrocyte morphology, may mediate brain injury due to radiofrequency exposure.

Suppression of Calbindin-D28k Expression Exacerbates SCA1 Phenotype in a Disease Mouse Model

Spinocerebellar ataxia type1 (SCA1) is an autosomal dominant neurological disorder caused by the expansion of a polyglutamine tract in the mutant protein ataxin-1. The cerebellar Purkinje cells (PCs) are the major targets of mutant ataxin-1. The mechanism of PC death in SCA1 is not known; however, previous work indicates that downregulation of specific proteins involved in calcium homeostasis and signaling by mutant ataxin-1 is the probable cause of PC degeneration in SCA1. In this study, we explored if targeted deprivation of PC specific calcium-binding protein calbindin-D28k (CaB) exacerbates ataxin-1 mediated toxicity in SCA1 transgenic (Tg) mice. Using behavioral tests, we found that though both SCA1/+ and SCA1/+: CaB null (-/+) double mutants exhibited progressive impaired performance on the rotating rod, a simultaneous enhancement of exploratory activity, and absence of deficits in coordination, the double mutants were more severely impaired than SCA1/+ mice. With increasing age, SCA1/+ mice showed a progressive loss in the expression and localization of CaB and other PC specific calcium-binding and signaling proteins. In double mutants, these changes were more pronounced and had an earlier onset. Gene expression profiling of young mice exhibiting no behavior or biochemical deficits revealed a differential expression of many genes common to SCA1/+ and CaB-/+ lines, and unique to SCA1/+: CaB-/+ phenotype. Our study provides further evidence for a critical role of CaB in SCA1 pathogenesis, which may help identify new therapeutic targets to treat SCA1 or other cerebellar ataxias.

Altered expression of neuropeptides in the primary somatosensory cortex of the Down syndrome model Ts65Dn

Down syndrome is the most common genetic disorder associated with mental retardation. Subjects and mice models for Down syndrome (such as Ts65Dn) show defects in the formation of neuronal networks in both the hippocampus and the cerebral cortex. The principal neurons display alterations in the morphology, density and distribution of dendritic spines in the cortex as well as in the hippocampus. Several evidences point to the possibility that the atrophy observed in principal neurons could be mediated by changes in their inhibitory inputs and, in fact, an imbalance between excitation and inhibition has been observed in Ts65Dn mice in these regions, which are crucial for learning and information processing. These animals have an increased density of interneurons in the primary somatosensory cortex, especially of those expressing calretinin and calbindin D-28k. Here, we have analysed the expression and distribution of several neuropeptides in the primary somatosensory cortex of Ts65Dn mice in order to investigate whether these subpopulations of interneurons are affected. We have observed an increase in the total density of somatostatin expressing interneurons and of those expressing VIP in layer IV in Ts65Dn mice. The typology of the somatostatin and VIP interneurons was unaltered as attested by the pattern of co-expression with other markers. Somatostatin immunoreactive neurons co-express mainly D-28k calbindin and VIP expressing interneurons maintain its pattern of co-expression with calcium binding proteins. These alterations, in case they were also present in subjects with Down syndrome, could be related to their impairment in cognitive profile and could be involved in the neurological defects observed in this disorder.

Different pattern of changes in calcium binding proteins immunoreactivity in the medial prefrontal cortex of rats exposed to stress models of depression

Reductions in the number and size of neurons in the medial prefrontal cortex (mPFC) have been documented in many post-mortem studies of depressed patients and animals exposed to stress. Here, we examined the effect of chronic unpredictable stress (CUS) and chronic mild stress (CMS) on specific populations of neurons in the rat mPFC. Antibodies directed against parvalbumin (PV), calbindin D-28K (CB) and active caspase-3 have been used to quantify the numerical density of PV-immunoreactive (PV-ir), CB-ir and active caspase-3-ir cells, and to measure the relative optical density of neuropil. CUS decreased the density of CB-ir neurons and the optical density of CB-ir neuropil. In turn, CMS increased the densities of both CB-ir neurons and neuropil, while PV-ir neurons and PV-ir neuropil were not changed. The frequency distribution of neuronal surface areas was significantly different only for PV-ir neurons, and only between the control and CUS group. CMS reduced the density of active caspase-3-ir cells while CUS did not. We concluded that the mPFC reveals a different pattern of changes in neurons containing calcium binding proteins and active caspase-3 immunoreactivity in response to CUS and CMS.

Hypothyroid States Mitigate the Diabetes-Induced Reduction of Calbindin D-28k, Calretinin, and Parvalbumin Immunoreactivity in Type 2 Diabetic Rats

In this study, we investigated the differences in calbindin D-28k (CB), calretinin, (CR) and parvalbumin (PV) immunoreactivity in the hippocampus of Zucker diabetic fatty (ZDF) rats and Zucker lean control (ZLC) rats. In addition, we observed the effects of hypothyroidism on the levels of immunoreactivity of these proteins in ZDF rats. For this study, 7-week-old ZDF rats were used, and methimazole treatment was continued for 5 weeks to induce hypothyroidism. The animals were sacrificed at 12 weeks of age. ZDF rats showed increased blood glucose levels compared to those in ZLC rats. Methimazole intervention significantly reduced total and free T3 levels, and it ameliorated the increase of blood glucose levels in ZDF rats. In ZLC rats, CB, CR, and PV immunoreactivity was detected in regions of the hippocampus proper. In vehicle-treated ZDF rats, CB, CR, and PV immunoreactivity was significantly decreased in the hippocampus. However, in the methimazole-treated rats, CB, CR, and PV immunoreactivity was significantly increased compared to that in the vehicle-treated rats. These results suggest that hypothyroidism ameliorated the diabetes-induced reduction of CB, CR, and PV immunoreactivity in the hippocampus.

Immunolocalization of steroidogenic acute regulatory protein-related lipid transfer (START) domain-containing proteins in the developing cerebellum of normal and hypothyroid rats

Cholesterol transport proteins are a prerequisite for neurosteroidogenesis. Steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domain-containing proteins, such as StAR and START domain-containing 6 (StarD6), are known to be distributed in the brain. Since perinatal hypothyroidism affects cerebellar development, we examined postnatal changes in StAR and StarD6 immunolocalization in the developing cerebellum of control and hypothyroid rats. Pregnant Sprague-Dawley rats were given 0.05% 6-propyl-2-thiouracil (PTU) or water from gestation day 11 until postnatal day (P) 28, and were then killed together with age-matched control rats. As shown by calbindin D-28k immunostaining, the developing cerebellar cytoarchitecture and Purkinje cells were affected by PTU-induced hypothyroidism as compared to control rats. The immunolocalization of StAR and StarD6 generally followed the maturation pattern of Purkinje cells from the vermis to the cerebellar hemisphere. StAR immunostaining first appeared in the Purkinje cells of the vermis at P7 in both control and hypothyroid rats. In control rats, a few StarD6 immunoreactive cells were seen at birth and a nuclear localization of StarD6 in Purkinje cells was obvious at P14. PTU-induced hypothyroidism delayed the appearance of StarD6 immunopositive cells until P7. Moreover, the nuclear localization of StarD6 in PTU-treated rats was not obvious at P14. An adult-like distribution of StAR and StarD6 was achieved by P21 in control and hypothyroid rats. These results suggest that StarD6 may affect the development of Purkinje cells during the first and second postnatal weeks, a known period of thyroid hormone action.

Calbindin D28K expression in relation to granule cell dispersion, mossy fibre sprouting and memory impairment in hippocampal sclerosis: A surgical and post mortem series

Reorganisation of the dentate gyrus, including granule cell dispersion (GCD) and mossy fibre sprouting, typically accompany hippocampal sclerosis (HS) in temporal lobe epilepsy. Calbindin (CB) expression in granule cells increases during infancy, influences granule cell excitability, vulnerability to excitotoxicity in addition to important physiological functions in memory. Our aim was to study CB patterns in relation to dentate gyrus re-organisation, epilepsy history and memory function. Forty-five surgical cases and 11 post mortems were examined from patients with drug-resistant epilepsy in addition to three post mortem controls. In the surgical cases, CB expression, and the degree of GCD and mossy fibre sprouting were measured. In post mortem cases, CB expression was assessed in relation to the pattern of HS along the rostral-caudal axis of the hippocampus, and compared to PM controls. Three patterns were identified. In Group 1 (40%), the most dispersed granule cells were CB-positive and basal cells negative imitating developmental patterns. In Group 2 (47%), normal CB expression was retained and in Group 3 (13%), CB was predominantly lost in granule cells. These patterns correlated with GCD, the presence of mossy fibre sprouting and the pattern of HS. Group 1 was associated with early onset of seizures but not independently predictive of outcome. In post mortem cases, altered CB expression lateralised to the side of HS and persisted despite seizure remission in some patients. No significant correlation between CB expression and memory function was identified. CB expression patterns in HS may indicate developmental dysmaturation and are associated with the extent of GCD and mossy fibre sprouting in HS. The functional significance of CB loss, in terms of epileptogenesis and effects on memory, remain uncertain.

Immunocytochemical Localization of Calcium-Binding Proteins, Calbindin D28K-, Calretinin-, and Parvalbumin-Containing Neurons in the Dog Visual Cortex

Although the dog is widely used to analyze the function of the brain, it is not known whether the distribution of calcium-binding proteins reflects a specific pattern in the visual cortex. The distribution of neurons containing calcium-binding proteins, calbindin D28K, calretinin, and parvalbumin in adult dog visual cortex were studied using immunocytochemistry. We also compared this labeling to that of gamma-aminobutyric acid (GABA). Calbindin D28K-immunoreactive (IR) neurons were predominantly located in layer II/III. Calretinin- and parvalbumin-IR neurons were located throughout the layers with the highest density in layers II/III and IV. The large majority of calbindin D28K-IR neurons were multipolar stellate cells. The majority of the calretinin-IR neurons were vertical fusiform cells with long processes traveling perpendicular to the pial surface. And the large majority of parvalbumin-IR neurons were multipolar stellate and round/oval cells. More than 90% of the calretinin- and parvalbumin-IR neurons were double-labeled with GABA, while approximately 66% of the calbindin D28K-IR neurons contained GABA. This study elucidates the neurochemical structure of calcium-binding proteins. These data will be informative in appreciating the functional significance of different laminar distributions of calcium-binding proteins between species and the differential vulnerability of calcium-binding proteins-containing neurons, with regard to calcium-dependent excitotoxic procedures.

Inflammation-Induced Changes in the Chemical Coding Pattern of Colon-Projecting Neurons in the Inferior Mesenteric Ganglia of the Pig

The present study examines the chemical coding of the inferior mesenteric ganglia after chemically induced colitis in the pig animal model. In all animals (n = 6), a median laparotomy was performed under anesthesia, and the Fast Blue retrograde tracer was injected into the descending colon wall. In experimental animals (n = 3), the thick descending colon were injected with formalin solution to induce inflammation. The animals were euthanized and the inferior mesenteric ganglion was harvested and processed for double-labeling immunofluorescence for calbindin-D28k (CB) in combination with either tyrosine hydroxylase (TH), neuropeptide Y (NPY), somatostatin (SOM), vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), Leu-enkephalin (LENK), substance P (SP), vesicular acetylcholine transporter (VAChT), or galanin (GAL). Immunohistochemistry revealed significant changes in the chemical coding pattern of inferior mesenteric ganglion neurons. In control animals, Fast Blue-positive neurons were immunoreactive to TH, NPY, SOM, VIP, LENK, CB, and NOS. In the experimental group, TH, NPY, SOM, VIP, and LENK expressing neurons were reduced, whereas the number of neurons immunoreactive to CB, NOS, and GAL were increased. The increase of so-called neuroprotective neuropeptides suggests that the changes in the chemical coding of inferior mesenteric ganglion neurons reflect adaption under pathological conditions to promote their own survival.

The effect of different maternal deprivation paradigms on the expression of hippocampal glucocorticoid receptors, calretinin and calbindin-D28k in male and female adolescent rats

Maternal deprivation (MD) is a well-established protocol used to investigate neurobiological changes that are associated with the etiology of and vulnerability to stress-related diseases in animal models. The resulting psychophysiological effects, the timing and duration of these adverse stimuli, and the method by which they exert their effects on the animals remain unclear. This study characterized differences in the hippocampal expression of glucocorticoid receptors (GRs) and the calcium-binding proteins calretinin (CALR) and calbindin-D28k (CALB) in male and female rats that underwent different MD paradigms during the stress hyporesponsive period (SHRP). Both GRs and the two calcium-binding proteins were much more abundant in females than in males. MD paradigms had a significant effect on CALR and CALB expression in both males and females but affected GR levels only in males. Additionally, expression of the two calcium-binding proteins in the hippocampus responded differently to MD-induced stress, especially in females. Taken together, these results indicate that females are able to modulate their response to stress better than males.

Development of calbindin-containing neurons in sympathetic ganglia of rats and cats

Calcium-binding proteins, like calretinin, calbindin (CA) D28K, and parvalbumin, are present in many types of cells, including neurons. CA-immunoreactive nerve cell bodies are common in adult rats in the sympathetic ganglia. In order to gain further insight into the neuroplasticity of sympathetic neurons during early postnatal ontogenesis, the purpose of this study was to immunocytochemically investigate the development of CA-containing neurons in para- and prevertebral ganglia in rats and cats.

Phenotypic changes in calbindin D28K immunoreactivity in the hippocampus of Fmr1 knockout mice

Fragile X syndrome (FXS), the most prevalent form of inherited mental retardation, is caused by the lack of FMRP (fragile mental retardation protein) as a result of the transcriptional silencing of the FMR1 gene. Here we analyze the immunohistochemical expression of the calbindin D28K protein in the hippocampus of Fmr1 knockout (KO) mice and compare it with that of their wildtype (WT) littermates. The spatial distribution pattern of calbindin-immunoreactive cells in the hippocampus was similar in WT and KO mice but for each age studied (ranging from 3.5-8 months) the dentate gyrus of Fmr1-KO mice showed a significant reduction in calbindin-immunoreactive granule cells. Also, the number of calbindin-immunoreactive cells was reduced in the CA1 pyramidal layer in KO mice compared to their WT littermates. In addition, Frm1-KO mice showed a group of calbindin-immunoreactive cells located only in the left CA3b subregion that was only sometimes observed in WT mice. Overall, the absence of FMRP results in a dysregulation of the calbindin protein expression in the hippocampus. This dysregulation is cell type- and time-dependent and as a consequence key elements of the hippocampal trisynaptic circuitry may lack calbindin in critical periods for normal memory/learning abilities to be achieved and may explain some of the FXS symptoms observed in the Fmr1-KO mouse model.

Two types of tyrosine hydroxylase-immunoreactive neurons in the zebrafish retina

The purpose of the present study is to identify the dopaminergic amacrine (DA) cells in the inner nuclear layer (INL) of zebrafish retina through immunocytochemistry and quantitative analysis. Two types of tyrosine hydroxylase-immunoreactive (TH-IR) cells appeared on the basis of dendritic morphology and stratification patterns in the inner plexiform layer (IPL). The first (DA1) was bistratified, with branching planes in both s1 and s5 of the IPL. The second (DA2) was diffuse, with dendritic processes branched throughout the IPL. DA1 and DA2 cells corresponded morphologically to A on −s1/s5 and A diffuse −1 ( Connaughton et al., 2004). The average number of total TH-IR cells was 1088 ± 79 cells per retina ( n = 5), and the mean density was 250 ± 27 cells/mm 2. Their density was highest in the mid central region of ventrotemporal retina and lowest in the periphery of dorsonasal retina. Quantitatively, 45.71% of the TH-IR cells were DA1 cells, while 54.29% were DA2 cells. No TH-IR cells expressed calbindin D28K, calretinin or parvalbumin, markers for the various INL cells present in several animals. Therefore the TH-IR cells in zebrafish are limited to very specific subpopulations of the amacrine cells.

Localization of Canine, Feline, and Mouse Renal Membrane Proteins

Immunohistochemistry allows the localization of proteins to specific regions of the nephron. This article reports the identification and localization of proteins in situ within normal canine, feline, and mouse kidney by immunohistochemistry; maps their distribution; and compares results to previously reported findings in other species. The proteins investigated are aquaporin 1, aquaporin 2, calbindin D-28k, glutathione S-transferase-α, and Tamm-Horsfall protein. Aquaporins are integral membrane proteins involved in water transport across cell membranes. Calbindin D-28k is involved in renal calcium metabolism. Glutathione S-transferase-α is a protein that aids in detoxification and drug metabolism. The role of Tamm-Horsfall protein is not fully understood. Proposed functions include inhibition of calcium crystallization and reduction of bacterial urinary tract infection. The authors' findings in the dog are similar to those in other species: Specifically, the authors localize aquaporin 1 to the proximal convoluted tubule epithelium, vasa recta endothelium, and descending thin limbs; aquaporin 2 to collecting duct epithelium; and calbindin D-28k within distal convoluted tubule epithelium. Glutathione S-transferase-α has variable expression and is found in only the renal transitional epithelium in some individuals, in only the proximal straight tubules in others, or in both locations in others. Tamm-Horsfall protein localizes to thick ascending limb epithelium. These findings are similar in the cat, with the exception that aquaporin 1 is located in glomerular podocytes, in addition to proximal convoluted tubule epithelium, and glutathione S-transferase-α is found solely within the proximal convoluted tubule within all kidney samples examined. The mouse kidney is almost identical to the dog but expresses glutathione S-transferase-α in the glomeruli only.

Upregulation of calbindin D28k in the late distal tubules in the potassium-loaded adrenalectomized mouse kidney

The calcium (Ca)-activated potassium (K) channel is an alternative K-secretory pathway in the apical membranes of the distal nephrons of adrenalectomized (ADX) animals. As a potential approach for estimating intracellular Ca(2+) increase, we investigated normal and ADX mice to determine whether dietary K intake would stimulate the expression of the calbindin D28k protein, a cytosolic Ca(2+)-binding protein, along the distal nephron consisting of the early and late portions of the distal convoluted tubule (DCT1 and DCT2, respectively), the CNT, and CCD. ADX mice received a control diet plus either 0.3% NaCl solution (C) or a 0.3% NaCl plus 3% KCl solution (HK) for 7 days before the experiment. The mean plasma K concentration and pH were significantly (P < 0.001) higher (7.9 ± 0.3 mEq/l) and lower (7.28 ± 0.02) in the K-loaded ADX mice than in the control ADX mice. The mean urinary K excretion (mEq/day) and urine flow (ml/day) increased significantly (P < 0.0001) from 0.47 ± 0.07 (C) to 4.80 ± 0.57 (HK) and from 1.1 ± 0.2 (C) to 8.8 ± 1.0 (HK). Urinary Ca excretion significantly (P < 0.005 and P < 0.05, respectively) increased in K-loaded normal and ADX mice compared with control normal and ADX mice. Immunofluorescence studies revealed that the relative staining of calbindin was 167.0 ± 15.4%, 291.3 ± 13.8%, and 206.3 ± 11.3% for DCT1, DCT2/CNT, and CCD of normal control mice, respectively. These values increased significantly (P < 0.0001) only in DCT2/CNT (574.8 ± 42%) of the K-loaded ADX mice. Upregulation of calbindin in the late distal tubule suggests that Ca(2+)-dependent K transport may function as an alternative mechanism for urinary K excretion in ADX mice.

Calcitriol in combination with dl-buthionine-S,R-sulfoximine induces alterations in growth, redox state and differentiation in neoplastic intestinal cells

Diabetes mellitus (DM) type I is a disorder characterized by hyperglycemia due to a deficient insulin secretion. Alterations in different organs have been observed in DM. The aim of this work was to study intestinal calcium absorption, alkaline phosphatase (AP) activity and the expression of some genes involved in calcium transport in an experimental diabetes model. Two-month old male Wistar rats were divided into two groups: control (n=5) and treated rats (n=5). Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) (60 mg/kg) after fasting for 12-hours. Control rats were injected with the vehicle. Serum and urine glucose were determined before and 5 days after STZ induction. Rats with glycemia over 250 mg/dL were considered diabetic. Intestinal calcium absorption was measured and AP activity from duodenal mucosa was assayed. Ca-ATPase pump and calbindin D28K gene expressions were analyzed by RT-PCR. The weight of the STZ-injected rats decreased after 5 days of the induction and the glucose levels were significantly higher than those of the control group (406±13 mg/dL vs 142±17 mg/dL, p<0.001). Diabetic rats had polyuria and glycosuria. Calcium absorption was lower in diabetic rats than in controls (0.26±0.01 nmol Ca/mL plasma vs 0.65±0.05 nmol Ca/mL plasma, p<0.001). AP activity was significantly lower in diabetic rats than in controls (0.31±0.06 IU/mg protein vs 0.59±0.10 IU/mg protein, p<0.05). Preliminary determinations show that the expression of the studied genes would be similar in both groups. To conclude, the metabolic alteration in DM would alter intestinal calcium absorption and AP activity. The molecular mechanisms responsible of these effects are under investigation. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.

Sodium deoxycholate alters the transcellular pathway of intestinal calcium absorption

Diabetes mellitus (DM) type I is a disorder characterized by hyperglycemia due to a deficient insulin secretion. Alterations in different organs have been observed in DM. The aim of this work was to study intestinal calcium absorption, alkaline phosphatase (AP) activity and the expression of some genes involved in calcium transport in an experimental diabetes model. Two-month old male Wistar rats were divided into two groups: control (n=5) and treated rats (n=5). Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) (60 mg/kg) after fasting for 12-hours. Control rats were injected with the vehicle. Serum and urine glucose were determined before and 5 days after STZ induction. Rats with glycemia over 250 mg/dL were considered diabetic. Intestinal calcium absorption was measured and AP activity from duodenal mucosa was assayed. Ca-ATPase pump and calbindin D28K gene expressions were analyzed by RT-PCR. The weight of the STZ-injected rats decreased after 5 days of the induction and the glucose levels were significantly higher than those of the control group (406±13 mg/dL vs 142±17 mg/dL, p<0.001). Diabetic rats had polyuria and glycosuria. Calcium absorption was lower in diabetic rats than in controls (0.26±0.01 nmol Ca/mL plasma vs 0.65±0.05 nmol Ca/mL plasma, p<0.001). AP activity was significantly lower in diabetic rats than in controls (0.31±0.06 IU/mg protein vs 0.59±0.10 IU/mg protein, p<0.05). Preliminary determinations show that the expression of the studied genes would be similar in both groups. To conclude, the metabolic alteration in DM would alter intestinal calcium absorption and AP activity. The molecular mechanisms responsible of these effects are under investigation. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.