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PubMed2005

Temperature sensitivity of calcium binding for parvalbumins from Antarctic and temperate zone teleost fishes.

Parvalbumin (PV) is a soluble calcium-binding protein that is especially abundant in fast-twitch muscles of fish and other lower vertebrates. Despite its prevalence in ectothermic taxa, few data address the effects of temperature on PV binding function. In this study, calcium dissociation constants (KD) were measured as a function of temperature (0-25 degrees C) for PV from two Antarctic (Gobionotothen gibberifrons and Chaenocephalus aceratus) and two temperate zone fish species (Cyprinus carpio and Micropterus salmoides). Measurements by fluorometric competitive binding assay show that KD values for PVs from the Antarctic species were significantly higher at all assay temperatures and were less sensitive to temperature relative to carp and bass. However, estimates of KD are fundamentally similar for PVs from the Antarctic and temperate zone species when examined at their native physiological temperature. Variation in pH and ionic strength within a physiologically relevant range had only modest effects on KD. Thermodynamics of calcium binding to PV from G. gibberifrons and C. carpio was measured by isothermal microcalorimetry. When measured at 15 degrees C, the Gibbs free energy change (deltaG) was significantly greater for calcium binding to PV from G. gibberifrons than from carp (-43.4+/-1.5 kJ mol(-1) and -46.6+/-3.0 kJ mol(-1), respectively), and the relative contribution of entropy to deltaG for calcium binding to PV from the Antarctic species was about twice that of carp (deltaS=16.0+/-0.8 J degrees C(-1) mol(-1) for G. gibberifrons; deltaS=7.5+/-0.8 J degrees C(-1) mol(-1) for C. carpio).

Animals↗
PubMed2004

Ectopic parvalbumin expression in mouse forebrain neurons increases excitotoxic injury provoked by ibotenic acid injection into the striatum.

A neuroprotective role for Ca(2+)-binding proteins in neurodegenerative conditions ranging from ischemia to Alzheimer's disease has been suggested in several studies. A key phenomenon in neurodegeneration is the Ca(2+)-mediated excitotoxicity brought about by the neurotransmitter glutamate. To evaluate the relative ability to resist excitotoxicity of neurons containing the slow-onset Ca(2+)-binding protein parvalbumin (PV), we injected the glutamate agonist ibotenic acid (IBO) into the striatum of adult mice ectopically expressing PV in neurons. Striatal ibotenic acid injection results in local nerve cell loss and reactive astrogliosis. Light microscopic evaluation, carried out after a delay of 2 and 4 weeks, reveals an enlarged and accelerated neurodegenerative process in mice ectopically expressing neuronal PV. Thus, PV is not neuroprotective, it rather enhances nerve cell death. This result implicates that the increase in cytosolic Ca(2+)-buffering capacity in the transgenic mice impairs other systems involved in Ca2+ sequestration. In addition, ultrastructural morphometric analysis shows that in neurons the mitochondrial volume is reduced in mice ectopically expressing neuronal PV. This is paralleled by a reduction in the amount of the mitochondrial marker enzyme cytochrome c oxidase subunit I (COXI). We conclude that alterations in the Ca(2+) homeostasis present in mice ectopically expressing neuronal PV are more deleterious under excitotoxic stress and largely outweigh the potential benefits of an increased Ca(2+)-buffering capacity resulting from PV.

Animals↗
PubMed2005

Modulation of parvalbumin expression in the motor cortex of parkinsonian rats.

Dopamine deficiency in Parkinson's disease leads to numerous molecular changes in basal ganglia. However, the consequences of these changes on the motor cortex remain unclear. Here we show that the immunoreactivity of parvalbumin, which is expressed in GABAergic interneurons, increases in the primary motor cortex of parkinsonian rats. This increase can be reversed by a subsequent lesion of the subthalamic nucleus. These results suggest that dopamine deficiency induces reversible changes in GABAergic cortical cells, which might be linked with parkinsonian symptoms.

Animals↗
PubMed2005

Allergy to fish parvalbumins: studies on the cross-reactivity of allergens from 9 commonly consumed fish.

BACKGROUND: Fish-hypersensitive patients can probably tolerate some fish species while being allergic to others. OBJECTIVE: To determine the allergenic cross-reactivity between 9 commonly edible fish: cod, salmon, pollack, mackerel, tuna, herring, wolffish, halibut, and flounder. METHODS: Sera from 10 patients allergic to fish and rabbit antisera against 3 parvalbumins (Gad c 1, Sal s 1, and The c 1) were used. Cross-reactivity was investigated by SDS/PAGE and IgE immunoblotting, IgG ELISA, IgE ELISA inhibition, and skin prick test (SPT). RESULTS: Cod (Gad c 1), salmon (Sal s 1), pollack (The c 1), herring, and wolffish share antigenic and allergenic determinants as shown by immunoblots and IgE ELISA, whereas halibut, flounder, tuna, and mackerel displayed lowest cross-reactivities. The highest mean IgE ELISA inhibition percent of 10 sera was obtained by Gad c 1, followed by The c 1, herring, Sal s 1, wolffish, halibut, flounder, tuna, and mackerel with the least inhibition. Nine of the 10 patients showed positive SPT to cod, salmon, and pollack; 8 patients reacted to recombinant (r) Sal s 1. Positive SPTs to rGad c 1 and rThe c 1 were demonstrated in 1 patient. CONCLUSION: Gad c 1, Sal s 1, The c 1, herring, and wolffish contained the most potent cross-reacting allergens, whereas halibut, flounder, tuna, and mackerel were the least allergenic in the current study. The latter could probably be tolerated by some of the tested patients.

Adult↗
PubMed2005

Visually-induced NGFI-A protein expression in the calbindin-, parvalbumin- and nitric oxide synthase-neuronal populations of the rat superior colliculus.

The expression of the immediate early gene NGFI-A in the nervous system is induced by sensory stimulation and seems to be related to long-term synaptic plasticity. We have used double-labeling immunohistochemistry to identify calbindin (CB)(+), parvalbumin (PV)(+) and neuronal nitric oxide synthase (nNOS)(+) neurons that also expressed the protein encoded by this immediate early gene after light-exposure on in the superficial layers of the rat superior colliculus (sSC). The majority of the NGFI-A(+) cells were not double-labeled for the tested markers. In the stratum zonale+stratum griseum superficiale (SZ/SGS), only 17.8%, 8.0% and 12.1% of NGFI-A(+) cells were also labeled for CB, PV or nNOS, respectively. In the stratum opticum (SO), only 10.5% of the NGFI-A(+) cells were also CB(+). Furthermore, only a small subset of each population expressed the NGFI-A protein after light-exposure. In the SZ/SGS, 35.7% of the CB(+), 32.1% of the PV(+) and 26.6% of the nNOS(+) neurons also expressed the NGFI-A. In the SO, 31.7% of the CB(+) neurons also expressed the NGFI-A. The proportional distribution of the nNOS(+)/NGFI-A(+) neurons throughout the SZ/SGS layers showed a slight but significant rostro-caudal gradient. No significant difference was observed for the other markers, indicating homogeneous activation of these populations throughout the retinotopic map. Our results suggest that the visually-driven NGFI-A expression is not restricted to a specific population of the sSC and that visual processing in this structure, as assessed by the expression of this candidate-plasticity protein, involves the activation of subsets of ascending and non-ascending projection neurons.

Animals↗
PubMed2004

Parvalbumin deficiency affects network properties resulting in increased susceptibility to epileptic seizures.

Networks of GABAergic interneurons are of utmost importance in generating and promoting synchronous activity and are involved in producing coherent oscillations. These neurons are characterized by their fast-spiking rate and by the expression of the Ca(2+)-binding protein parvalbumin (PV). Alteration of their inhibitory activity has been proposed as a major mechanism leading to epileptic seizures and thus the role of PV in maintaining the stability of neuronal networks was assessed in knockout (PV-/-) mice. Pentylenetetrazole induced generalized tonic-clonic seizures in all genotypes, but the severity of seizures was significantly greater in PV-/- than in PV+/+ animals. Extracellular single-unit activity recorded from over 1000 neurons in vivo in the temporal cortex revealed an increase of units firing regularly and a decrease of cells firing in bursts. In the hippocampus, PV deficiency facilitated the GABA(A)ergic current reversal induced by high-frequency stimulation, a mechanism implied in the generation of epileptic activity. We postulate that PV plays a key role in the regulation of local inhibitory effects exerted by GABAergic interneurons on pyramidal neurons. Through an increase in inhibition, the absence of PV facilitates synchronous activity in the cortex and facilitates hypersynchrony through the depolarizing action of GABA in the hippocampus.

Action Potentials↗
PubMed2004

Differential effects of spontaneous versus forced exercise in rats on the staining of parvalbumin-positive neurons in the hippocampal formation.

To investigate whether the type of physical activity, voluntary or forced, would promote different morphological changes in hippocampal formation we performed an immunocytochemical study using the parvalbumin (PV) distribution as a marker. Animals submitted to the voluntary exercise were placed in a voluntary wheel running and those submitted to the forced exercise were placed in a motor driven treadmill. Both exercise groups were submitted to 10 consecutive days of physical activity. It was observed a higher number of PV-positive cells in the hilus of dentate gyrus (DG) in the voluntary and forced exercise groups when compared to the control group. The voluntary exercise group also presented a stronger fiber staining in the DG hilus than the forced exercise and control groups. In contrast, no differences were found in the pattern of PV staining in CA1/CA3 region between exercise and control groups. These findings demonstrate that physical activity leads to prominent plastic changes in the hippocampal formation of rats that were more evident following voluntary activity.

Animals↗
PubMed2005

Chronic haloperidol or clozapine treatment does not alter parvalbumin immunoreactivity in the rat frontal cortex or hippocampus.

GABAergic neuronal subpopulations, defined by the presence of the calcium binding proteins, parvalbumin (PV) and calretinin (CR) are differentially affected in schizophrenia, with selective PV deficits reported in the prefrontal cortex and hippocampus. To assess the possible contribution of antipsychotic treatment to these effects we examined the size and density of PV-and CR-IR neurons in the rat frontal cortex and hippocampus following three weeks of chronic haloperidol or clozapine administration. Neither antipsychotic significantly altered PV- or CR-IR neuronal cell parameters in these areas or in any of their subregions, relative to controls. These results suggest antipsychotic exposure does not contribute to PV-IR neuronal deficits in schizophrenic patients, providing further evidence in support of a developmental abnormality in specific subpopulations of GABAergic neurons in schizophrenia.

Animals↗
PubMed2004

Ethanol withdrawal reduces cerebellar parvalbumin expression in a manner reversed by estrogens.

Parvalbumin (PA) is a calcium-binding protein that has been implicated in neuroprotection. We examined whether the stimulus effect of ethanol withdrawal (EW) alters the expression of PA in a manner that is prevented by 17beta-estradiol (E2). Ovariectomized rats implanted with E2 (EW/E2) or oil (EW/Oil) pellets received chronic ethanol (7.5%, w/v, 5 weeks) or control dextrin diets (Dex/Oil). At 24h of EW, rats were tested for overt EW signs, and the cerebellum was prepared for immunoblotting and immunohistological assessment for PA. The EW/Oil group showed a higher EW sign score, a lower PA expression, and fewer PA-positive Purkinje neurons than the dextrin control group. In the EW/E2 group, EW sign scores, PA expression, and PA-positive Purkinje neurons were not significantly different from those in the control dextrin group. These data suggest that E2 treatment protects against the PA-suppression associated with EW toxicity.

Animals↗
PubMed2005

Changes of parvalbumin immunoreactive neurons and GFAP immunoreactive astrocytes in the rat lateral geniculate nucleus following monocular enucleation.

The expression of calcium binding proteins (CaBPs) has been linked to protection of neurons. The present study investigated the effects of monocular enucleation on the distribution of parvalbumin immunoreactive (PV-IR) neurons and glial fibrillary acidic protein immunoreactive (GFAP-IR) astrocytes in both the dorsal (dLGN) and ventral (vLGN) regions of the lateral geniculate nucleus (LGN). Our results demonstrated an increase in PV-IR neuronal density on the contralateral vLGN at 1-week post-enucleation (PE), which was maintained without significant change for 12 weeks. By contrast, PV-IR neurons in dLGN decreased significantly at all time point examined. The number of GFAP-IR astrocytes showed an initial increase from 1 to 4 weeks PE and then gradually decreased until 48 weeks in both regions of the LGN with contralateral side predominance. The present results suggest that monocular enucleation results in variable expression of PV-IR neurons and GFAP-IR astrocytes in the LGN complex, which may play an important role in neuronal degeneration and neuroplasticity of the rat visual system.

Animals↗
PubMed2006

Mu opioid receptors are extensively co-localized with parvalbumin, but not somatostatin, in the dentate gyrus.

In the rat dentate gyrus, mu opioid receptor (MOR) agonists disinhibit principal cells, promoting excitation, but whether MOR protein is differentially distributed to interneuron subtypes is unknown. Here, the distribution of MOR immunoreactivity was semi-quantitatively examined in neurochemically identified interneurons using fluorescence microscopy. We find that MOR- and parvalbumin-immunoreactivities are frequently co-localized, while MOR- and somatostatin-immunoreactivities are less commonly co-localized. This suggests that MORs are most frequently on interneurons specialized to inhibit granule cell output, and are on a limited number of interneurons that inhibit granule cell distal dendrites.

Animals↗
PubMed2006

Up-regulation of P/Q-type voltage-gated Ca2+ channel immunoreactivity within parvalbumin positive neurons in the rat hippocampus following status epilepticus.

To identify the roles of VGCC subtypes in damages/impairs of inhibitory transmission during epileptogenesis, we investigated temporal- and spatial-specific alterations in voltage-gated Ca(2+) channel (VGCC) immunoreactivities within parvalbumin (PV, a Ca(2+) binding protein) positive neurons in the rat hippocampus following status epilepticus (SE). Compared to controls, only P/Q-type (alpha1A) VGCC immunoreactivity was enhanced in PV positive neurons at the early point following SE. The alteration in P/Q-type (alpha1A) VGCC immunoreactivity showed an inverse proportionality to that in PV immunoreactivity in the dentate gyrus and the CA1 region. These findings suggest that SE may induce prolonged up-regulation in P/Q-type VGCC expression within PV positive neurons.

Animals↗
PubMed2004

Repeated application of ketamine to rats induces changes in the hippocampal expression of parvalbumin, neuronal nitric oxide synthase and cFOS similar to those found in human schizophrenia.

Treatment with the phencyclidine derivative ketamine, a non-competitive N-methyl-D-aspartate receptor antagonist and a well known anesthetic, has recently been introduced to mimic schizophrenia in animals. Using rats repeatedly treated with sub-anesthetic doses we demonstrate in the hippocampal formation the cellular distribution patterns of proteins being relevant to the pathogenesis of schizophrenia. Compared with controls an increase in the density of reduced nicotinamide adenine dinucleotide phosphate diaphorase-, neuronal nitric oxide synthase- and cFOS-positive hippocampal interneurons was found, whereas the density of parvalbumin expressing cells was decreased. Our experiments show that repeated injections of sub-anesthetic doses of ketamine induce significant changes in the nitrergic and GABAergic system which, in part, resemble those described in postmortem brains of human schizophrenics indicating that sub-chronic treatment with sub-anesthetic doses of ketamine might be a useful animal model to study schizophrenia.

Animals↗
PubMed2005

Localization of M2 muscarinic receptor protein in parvalbumin and calretinin containing cells of the adult rat entorhinal cortex using two complementary methods.

We investigated parvalbumin (PV) and calretinin (CR) containing interneurons in the rat entorhinal cortex. RNA amplification following single cell dissection of immunohistochemically labeled cells from layers II to VI revealed that PV cells, in contrast to CR cells, express the m2 muscarinic receptor (M2AchR) protein. Double immunostaining to confirm the results of RNA amplification indicated that the majority of PV cells contain M2AchR protein, whereas only a small proportion of CR cells do. In contrast, a large number of layer I CR cells, which are mostly Cajal-Retzius cells, were positive for M2AchR. RNA amplification following dissection of these cells also revealed that they contain the M2AchR protein. These findings emphasize that there are significant differences in the expression of different proteins, even among similar neuronal types in the same brain region. This highlights the importance of accurately collecting single cells, and knowledge of anatomical details in molecular biological studies.

Animals↗
PubMed2006

Amygdala input monosynaptically innervates parvalbumin immunoreactive local circuit neurons in rat medial prefrontal cortex.

The projection from the basolateral nucleus of the amygdala (BLA) conveys information about the affective significance of sensory stimuli to the medial prefrontal cortex (mPFC). By using an anterograde tract-tracing procedure combined with immunocytochemistry and correlated light/electron microscopical examination, labeled BLA afferents to layers 2-6 of the rat mPFC are shown to establish asymmetrical synaptic contacts, not only with dendritic spines (approximately 95.7% of targets innervated), but also with the aspiny dendritic shafts and somata of multipolar parvalbumin immunopositive (PV+) neurons. A population of PV- dendritic shafts was also innervated. Labeled BLA synaptic input to identified PV+ structures occurred in layers 2-6 of mPFC. The results indicate that labeled BLA afferents predominantly contact the spiny processes of presumed pyramidal cells and also provide a direct and specific innervation to a sub-population of local circuit neurons in mPFC containing PV. Since PV+ cells include two significant classes of fast-spiking GABAergic inhibitory interneuron (basket and axo-axonic cells), these novel observations indicate that the amygdalocortical pathway in the rat has the ability to directly influence functionally strategic 'feed-forward' inhibitory mechanisms at the first stage of processing amygdalocortical information.

Afferent Pathways↗
PubMed2006

Deficiency in parvalbumin, but not in calbindin D-28k upregulates mitochondrial volume and decreases smooth endoplasmic reticulum surface selectively in a peripheral, subplasmalemmal region in the soma of Purkinje cells.

The Ca(2+)-binding proteins parvalbumin (PV) and calbindin D-28k (CB) are key players in the intracellular Ca(2+)-buffering in specific cells including neurons and have profound effects on spatiotemporal aspects of Ca(2+) transients. The previously observed increase in mitochondrial volume density in fast-twitch muscle of PV-/- mice is viewed as a specific compensation mechanism to maintain Ca(2+) homeostasis. Since cerebellar Purkinje cells (PC) are characterized by high expression levels of the Ca(2+) buffers PV and CB, the question was raised, whether homeostatic mechanisms are induced in PC lacking these buffers. Mitochondrial volume density, i.e. relative mitochondrial mass was increased by 40% in the soma of PV-/- PC. Upregulation of mitochondrial volume density was not homogenous throughout the soma, but was selectively restricted to a peripheral region of 1.5 microm width underneath the plasma membrane. Accompanied was a decreased surface of subplasmalemmal smooth endoplasmic reticulum (sPL-sER) in a shell of 0.5 microm thickness underneath the plasma membrane. These alterations were specific for the absence of the "slow-onset" buffer PV, since in CB-/- mice neither changes in peripheral mitochondria nor in sPL-sER were observed. This implicates that the morphological alterations are aimed to specifically substitute the function of the slow buffer PV. We propose a novel concept that homeostatic mechanisms of components involved in Ca(2+) homeostasis do not always occur at the level of similar or closely related molecules. Rather the cell attempts to restore spatiotemporal aspects of Ca(2+) signals prevailing in the undisturbed (wildtype) situation by subtly fine tuning existing components involved in the regulation of Ca(2+) fluxes.

Animals↗
PubMed2004

Parvalbumin gene delivery improves diastolic function in the aged myocardium in vivo.

Abnormal relaxation of the heart, termed diastolic dysfunction, is a significant and growing problem that is a major cause of heart failure in the aged population. The potential of gene transfer of parvalbumin (Parv), a cytoplasmic calcium-binding protein, to improve diastolic function in the aged myocardium in vivo was evaluated. Despite evidence for an early developmental influence on the efficiency of Ad5 striated muscle transduction, results show that Ad5 gene transfer efficiency to adult cardiac myocytes in vitro is identical in young and old rats, suggesting that the basic processes of adenovirus binding and internalization are unaffected by aging. In contrast, Ad5-mediated Parv gene transfer to the myocardium in vivo is reduced in old rats compared to young rats. Nonetheless, Parv gene transfer and expression in vivo were sufficient to improve tau, a load-independent indicator of diastolic function, assessed using catheter-based micromanometry in the aged myocardium. These results suggest that expression of the calcium buffer Parv may represent an effective approach to functional correction of the failing heart in the aging.

Adenoviridae↗
PubMed2002

Optimal range for parvalbumin as relaxing agent in adult cardiac myocytes: gene transfer and mathematical modeling.

Parvalbumin (PV) has recently been shown to increase the relaxation rate when expressed in intact isolated cardiac myocytes via adenovirus gene transfer. We report here a combined experimental and mathematical modeling approach to determine the dose-response and the sarcomere length (SL) shortening-frequency relationship of PV in adult rat cardiac myocytes in primary culture. The dose-response was obtained experimentally by observing the PV-transduced myocytes at different time points after gene transfer. Calcium transients and unloaded mechanical contractions were measured. The results were as follows. At low estimated [PV] (approximately 0.01 mM), contractile parameters were unchanged; at intermediate [PV], relaxation rate of the mechanical contraction and the decay rate of the calcium transient increased with little effects on amplitude; and at high [PV] (approximately 0.1 mM), relaxation rate was further increased, but the amplitudes of the mechanical contraction and the calcium transient were diminished when compared with control myocytes. The SL shortening-frequency relationship exhibited a biphasic response to increasing stimulus frequency in controls (decrease in amplitude and re-lengthening time from 0.2 to 1.0 Hz followed by an increase in these parameters from 2.0 to 4.0 Hz). The effect of PV was to flatten this frequency response. This flattening effect was partly explained by a reduction in the variation in fractional binding of PV to calcium during beats at high frequency. In conclusion, experimental results and mathematical modeling indicate that there is an optimal PV range for which relaxation rate is increased with little effect on contractile amplitude and that PV effectiveness decreases as the stimulus frequency increases.

Animals↗