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L Lachowicz

Publications and source records attributed to L Lachowicz.

At least 19 recordsLinked to original sources
PubMed2005

Estradiol modulates the synapsins phosphorylation by various protein kinases in the rat brain under in vitro and in vivo conditions.

Synapsins are the neuronal phosphoproteins which play very important role in processes of synaptic neurotransmission. They are physiological substrates for Ser/Thr protein kinases. The reversible phosphorylation of synapsins may be modified by several compounds including steroid hormones. The aim of our study was to investigate, if the one of neuroactive steroid--17beta-estradiol--could modulate the phosphorylation of synapsins by PKA, CaM-PK and PKC in rat brain and what type of mechanism of their action is possible. The activity of kinases was evaluated as phosphorylation of synapsin in cerebral cortex and hippocampus in vivo and in vitro conditions. We conclude that 17E2 has inhibitory effect on synapsins phosphorylation by all tested kinases in vitro and in vivo conditions. The lack of nuclei in synaptosomal membrane fraction and short time of hormone exposure can be evidence of direct, non-genomic mechanism of estradiol action.

Animals↗
PubMed2001

Calmodulin effect on purified rat cortical plasma membrane Ca(2+)-ATPase in different phosphorylation states.

The plasma membrane Ca(2+)-ATPase in neuronal tissue plays an important role in fine tuning of the intracellular Ca(2+) concentration. The enzyme exhibits a high degree of tissue specificity and is regulated by several mechanisms. Here we analysed the relationship between separate modes of Ca(2+)-ATPase regulation, i.e., reversible phosphorylation processes mediated by protein kinases A and C, protein phosphatases PP1 and PP2A, and stimulation by calmodulin. The activity of PKA- or PKC-phosphorylated Ca(2+)-ATPase was influenced by the further addition of calmodulin, and this effect was more pronounced for PKC-phosphorylated calcium pump. In both cases the fluorescence study revealed the increased calmodulin binding, and for PKA-mediated phosphorylation it was correlated with a higher affinity of calcium pump for calmodulin. The incubation of Ca(2+)-ATPase with CaM prior to protein kinases action revealed that CaM presence counteracts the stimulatory effect of PKA and PKC. Under the in vitro assay cortical Ca(2+)-ATPase was a substrate for PP1 and PP2A. Protein phosphatases decreased both the basal activity of Ca(2+)-ATPase and its affinity for calmodulin. Fluorescence analysis confirmed the lowered ability of dephosphorylated Ca(2+)-ATPase for calmodulin binding. These results may suggest that interaction of CaM with calcium pump and its stimulatory action could be a partly separate phenomenon that is dependent on the phosphorylation state of Ca(2+)-ATPase.

Animals↗
PubMed1999

Short-time effects of neuroactive steroids on rat cortical Ca2+-ATPase activity.

Recent experimental evidence indicates that some steroid hormones, apart from their well-documented genomic actions, could produce non-genomic rapid effects, and are potent modulators of the plasma membrane proteins, including voltage- and ligand-operated ion channels or G protein-coupled receptors. Neuroactive steroids, 17beta-estradiol, testosterone, pregnenolone sulfate and dehydroepiandrosterone sulfate, after a short-time incubation directly modulated the activity of plasma membrane Ca2+-ATPase purified from synaptosomal membranes of rat cortex. The sulfate derivatives of dehydroepiandrosterone and pregnenolone applied at concentrations of 10-11-10-6 M, showed an inverted U-shape potency in the regulation of Ca2+-ATPase activity. At physiologically relevant concentrations (10-8-10-9 M) a maximal enhancement of the basal activity reached 200%. Testosterone (10-11-10-6 M) and 17beta-estradiol (10-12-10-9 M) caused a dose-dependent increase in the hydrolytic ability of Ca2+-ATPase, and the activity with the highest concentration of steroids reached 470% and 200%, respectively. All examined steroids decreased the stimulatory effect of a naturally existing activator of the calcium pump, calmodulin. The present study strongly suggests that the plasma membrane calcium pump could be one of the possible membrane targets for a non-genomic neuroactive steroid action.

Animals↗
PubMed1998

Protein kinases A and C phosphorylate purified Ca2+-ATPase from rat cortex, cerebellum and hippocampus.

The plasma membrane Ca2+-ATPase (PMCA), the enzyme responsible for the maintenance of intracellular calcium homeostasis, is regulated by several independent mechanisms. In this paper we report that the protein kinases A and C differentially activate the Ca2+-ATPase purified from synaptosomal membranes of rat cortex, cerebellum and hippocampus. The effect of protein kinases was more pronounced for the cortical enzyme, whereas cerebellar and hippocampal Ca2+-ATPases were activated to a lesser degree. The preparation of Ca2+-ATPase contained the phosphoamino acids, i.e., P-Ser and P-Thr, indicating that the enzyme was purified in phosphorylated state. The phosphorylation of Ca2+-ATPase by PKA and PKC increased the amount of phosphoamino acids, but in a region-dependent manner. Using the specific antibodies against N-terminal portion of four main PMCA isoforms we have characterized the isoforms composition of Ca2+-ATPase purified from the nervous endings of examined brain areas. Our results indicate that the activity of calcium pump is related to its phosphorylated state, and that the phosphorylation is region-dependent. Moreover, the differences observed could be related to the composition of PMCA isoforms in the different brain areas. Phosphorylation of the plasma membrane Ca2+-ATPase appears to be a mechanism to control its activity. The results support also the possible involvement of PKA and PKC.

Animals↗
PubMed1998

Differential effects of somatostatin and its analog on protein tyrosine kinases activity in the rat pituitary and the murine colonic tumors.

The effects of the native somatostatin-14 (SST-14) and of its analog octreotide (OCT) on the activity of protein tyrosine kinases (PTK) in the normal rat anterior pituitary gland, diethylstilbestrol (DES)-induced rat pituitary tumor and murine colonic cancer Colon 38 were studied in vitro. PTK activity was estimated in tissue homogenates using gamma-[32P]ATP and poly (Glu80, Tyr20) as a substrate. It was found that both SST-14 and OCT suppressed the PTK activity in all examined tissues. The suppressive effect was more pronounced in DES-induced pituitary tumor than in normal anterior pituitary gland, and in the former, OCT was more effective than SST-14. In contrast, SST-14 stronger suppressed PTK activity in colonic cancer than OCT. We hypothesize that SST-14 acts on PTK activity in colonic cancer mainly via SSTR-1 subtype of somatostatin receptors.

Animals↗
PubMed1996

Okadaic acid as a probe for regulation in vitro of Mg(2+), Ca(2+)-ATPase activity in rat cortical and cerebellar synaptosomal membranes.

The in vitro effect of okadaic acid on basal phorbol 12-myristate 13-acetate (PMA)-, and cyclic adenosine monophosphate (cAMP)-stimulated Mg(2+)-dependent Ca(2+)-adenosine triphosphatase (ATPase) activity in synaptosomal membranes isolated from rat brain cortex and cerebellum was investigated. The basal activity was enhanced by okadaic acid in both examined regions. This inhibitor differed in the regulation of Mg2+, Ca(2+)-ATPase activity in PMA- and cAMP-incubated membranes. Stimulation by calmodulin (CaM) of basal Mg2+, Ca(2+)-ATPase activity declined in cortex and cerebellum after treatment with okadaic acid. The presence of PMA or cAMP decreases the stimulatory effect of CaM. These results suggest that Mg2+, Ca(2+)-ATPase activity in the rat-brain synaptosomal membrane may be regulated in vitro by dephosphorylation processes.

Animals↗
PubMed1995

Neuroactive steroids modulate in vivo the Mg2+/Ca(2+)-ATPase activity in rat cortical and cerebellar synaptosomal membranes.

Estradiol and pregnenolone sulfate administered in vivo inhibited the Mg2+/Ca(2+)-ATPase activity in synaptosomal membranes from rat cortex by 20% and 30%, respectively. In cerebellum, estradiol decreased the activity up to 43%. The calmodulin-stimulated activity declined in cortex after treatment with estradiol and pregnenolone sulfate, but significantly increased in cerebellar membranes. Dehydroepiandrosterone sulfate had influence neither on enzyme activity, nor on stimulation by calmodulin in both examined rat brain regions.

Animals↗
PubMed1995

Estradiol and pregnenolone sulfate could modulate PMA-stimulated and Ca2+/calmodulin-dependent synaptosomal membrane protein phosphorylation from rat brain in vivo.

We have examined the effect of two steroids, pregnenolone sulfate and 17-beta-estradiol, on the activity of two protein kinases: protein kinase C and Ca2+/calmodulin-dependent protein kinase. The activity of the kinases was evaluated as phosphorylation of two synapsins Ia and Ib in cerebral cortex and hippocampus of the rat brain. Both steroids decreased phosphorylation of both synapsins to a great extent; however, in hippocampus neither pregnenolone nor estradiol influenced the reaction catalyzed by Ca2+/calmodulin-protein kinase. In the remaining areas of the brain estradiol decreased the activity of both studied kinases to a greater degree than pregnenolone sulfate. Our study suggests that pregnenolone sulfate and 17-beta-estradiol could modulate directly Ca2+/calmodulin-dependent protein kinase and protein kinase C and thus directly influence processes of neurotransmission.

Animals↗
PubMed1995

[Acid-base balance in capillary blood of newborns with perinatal hypoxemia symptoms].

The purpose of the study was to compare acid-base parameters in capillary blood of newborns from groups with hypoxaemia symptoms and from the control group (physiological deliveries). 111 newborns were divided into 8 groups. Group I consisted of 33 newborns from uncomplicated labour while groups II-VIII involved newborns from complicated labor with symptoms of hypoxaemia. Capillary blood was taken in the 10th and 60th minute and after 24 hours of newborn's life. In newborns with pathological CTG, green amniotic fluid and prolonged first stage of labour--higher duration of acidosis was observed.

Acid-Base Equilibrium↗
PubMed1995

[Analysis of mean differences for acid-base balance parameters in blood from umbilical arteries and veins of newborns with perinatal hypoxemia].

Arterio-venous differences in acid-base parameters of umbilical vessels blood using Nickelsen and Weber method and SPSS/PC+ computer's program were calculated. The mean differences are dependent on fetal metabolism, umbilical blood flow and placental gas exchange. Arterio-venous differences--normal or increased for pH, PCO2, PO2 and SO2 are valuable diagnostic indicators of accurate gas exchange while decreased values of these differences should predict placental dysfunction. Small differences are signs of chronic fetus hypoxaemia originated by anaerobic metabolism and increased the fetal lactic acid production, respectively.

Acid-Base Equilibrium↗
PubMed1994

Vanadium inhibition of human parietal lobe ATPases.

In vitro influence of vanadate and vanadyl ions on the activities of Na,K- and Ca,Mg-ATPase from synaptosomal membranes of the parietal lobe of the human brain were compared. 1. Vanadate and vanadyl inhibit the enzymes activities in the investigated fraction. 2. Vanadate is a more effective inhibitor of both ATPases in the concentrations above 50 microM and vanadyl is an effective inhibitor in a very low concentration (10 nM). 3. Vanadate seems to be an uncompetitive inhibitor of Na,K-ATPase (K1 = 880 nM).

Ca(2+) Mg(2+)-ATPase↗