A Review of Resistance Mechanisms to Bruton's Kinase Inhibitors in Chronic Lymphocytic Leukemia

Bruton's Tyrosine Kinase (BTK) inhibitors have become one of the most vital drugs in the therapy of chronic lymphocytic leukemia (CLL). Inactivation of BTK disrupts the B-cell antigen receptor (BCR) signaling pathway, which leads to the inhibition of the proliferation and survival of CLL cells. BTK inhibitors (BTKi) are established as leading drugs in the treatment of both treatment-naïve (TN) and relapsed or refractory (R/R) CLL. Furthermore, BTKi demonstrate outstanding efficacy in high-risk CLL, including patients with chromosome 17p deletion, TP53 mutations, and unmutated status of the immunoglobulin heavy-chain variable region (IGHV) gene. Ibrutinib is the first-in-class BTKi which has changed the treatment landscape of CLL. Over the last few years, novel, covalent (acalabrutinib, zanubrutinib), and non-covalent (pirtobrutinib) BTKi have been approved for the treatment of CLL. Unfortunately, continuous therapy with BTKi contributes to the acquisition of secondary resistance leading to clinical relapse. In recent years, it has been demonstrated that the predominant mechanisms of resistance to BTKi are mutations in BTK or phospholipase Cγ2 (PLCG2). Some differences in the mechanisms of resistance to covalent BTKi have been identified despite their similar mechanism of action. Moreover, novel mutations resulting in resistance to non-covalent BTKi have been recently suggested. This article summarizes the clinical efficacy and the latest data regarding resistance to all of the registered BTKi.

Real-World Outcome and Prognostic Factors in MDS Patients Treated with Azacitidine-A Retrospective Analysis

Azacitidine (AZA) is recognized as a vital drug used in the therapy of myelodysplastic syndromes (MDS) due to its beneficial effect on survival and quality of life. Nevertheless, many patients fail to respond to AZA treatment, as prognostic factors still are not identified. The present retrospective analysis included 79 patients with MDS treated with AZA as first-line therapy in a real-life setting. The percentage of patients with good, intermediate, and poor cytogenetics was 46.8%, 11.4%, and 34.2%, respectively. The overall response rate (complete remission [CR], partial remission [PR], and hematological improvement [HI]) was 24%. The CR, PR, and HI rates were 13.9%, 2.5%, and 7.6%, respectively. Stable disease (SD) was documented in 40.5% of patients. The median overall survival (OS) and progression-free survival (PFS) were 17.6 and 14.96 months, respectively. Patients with ORR and SD had a significantly longer median OS (23.8 vs. 5.7 months, p = 0.0005) and PFS (19.8 vs. 3.5 months, p < 0.001) compared to patients who did not respond to AZA. In univariate analysis, only an unfavorable cytogenetic group was a prognostic factor of a lower response rate (p = 0.03). In a multivariate model, older age (p = 0.047), higher IPSS (International Prognostic Scoring System) risk (p = 0.014), and higher IPSS-R cytogenetic risk (p = 0.004) were independent factors of shorter OS. Independent prognostic factors for shorter PFS were age (p = 0.001), IPSS risk (p = 0.02), IPSS cytogenetic risk (p = 0.002), and serum ferritin level (p = 0.008). The safety profile of AZA was predictable and consistent with previous studies. In conclusion, our study confirms the efficacy and safety of AZA in a real-world population and identifies potential biomarkers for response and survival.

Overlapping stimulation of subthalamic nucleus and dentato-rubro-thalamic tract in Parkinson's disease after deep brain stimulation

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces tremor, rigidity, and akinesia. According to the literature, the dentato-rubro-thalamic tract (DRTt) is verified target for DBS in essential tremor; however, its role in the treatment of Parkinson's disease is only vaguely described. The aim of our study was to identify the relationship between symptom alleviation in PD patients and the distance of the DBS electrode electric field (EF) to the DRTt.

METHODS

A single-center retrospective analysis of patients (N = 30) with idiopathic Parkinson's disease (PD) who underwent DBS between November 2018 and January 2020 was performed. DRTt and STN were visualized using diffusion-weighted imaging (DWI) and tractography protocol of magnetic resonance (MR). The EF was calculated and compared with STN and course of DRTt. Evaluation of patients before and after surgery was performed with use of UPDRS-III scale. The association between distance from EF to DRTt and clinical outcomes was examined. To confirm the anatomical variation between DRTt and STN observed in tractography, white matter dissection was performed with the Klingler technique on ten human brains.

RESULTS

Patients with EF overlapping STN and DRTt benefited from significant motor symptoms improvement. Anatomical findings confirmed the presence of population differences in variability of the DRTt course and were consistent with the DRTt visualized by MR.

CONCLUSIONS

DRTt proximity to STN, the main target in PD DBS surgery, confirmed by DWI with tractography protocol of MR combined with proper predefined stimulation parameters may improve efficacy of DBS-STN.

The Real-World Evidence on the Fragility and Its Impact on the Choice of Treatment Regimen in Newly Diagnosed Patients with Multiple Myeloma over 75 Years of Age

Fragility scales are intended to help in therapeutic decisions. Here, we asked if the fragility assessment in MM patients ≥ 75 years old qualified for treatment by the local physician correlates with the choice of treatment: a two- or three-drug regimens. Between 7/2018 and 12/2019, we prospectively enrolled 197 MM patients at the start of treatment from the 13 Polish Myeloma Group centers. The data to assess fragility were prospectively collected, but centrally assessed fragility was not disclosed to the local center. The activity of daily living (ADL) could be assessed in 192 (97.5%) and was independent in 158 (80.2%), moderately impaired in 23 (11.7%), and 11 (5.6%) in completely dependent. Patients with more than three comorbidities made up 26.9% (53 patients). Thus, according to the Palumbo calculator, 43 patients were in the intermediate fitness group (21.8%), and the rest belonged to the frailty group (153, 77.7%). Overall, 79.7% of patients (157) received three-drug regimens and 20.3% (40) received two-drug regimens. In each ECOG group, more than three out of four patients received three-drug regimens. According to the ADL scale, 82.3% of the independent 65.2% of moderately impaired, and 81.8% of the dependent received three-drug regimens. Out of 53 patients with at least four comorbidities, 71.7% received three-drug regimens, and the rest received two-drug regimens. Thirty-four patients from the intermediate fit group (79.0%), and 123 (79.9%) from the frail group received three-drug regimens. Early mortality occurred in 25 patients (12.7%). No one discontinued treatment due to toxicity. To conclude, MM patients over 75 are mainly treated with triple-drug regimens, not only in reduced doses, regardless of their frailty scores. However, the absence of prospective fragility assessment did not negatively affect early mortality and the number of treatment discontinuations, which brings into question the clinical utility of current fragility scales in everyday practice.

Importance of substratum quality for potential competitive niche overlap between native and invasive unionid mussels in Europe

Infaunal freshwater mussels are highly threatened and declining worldwide. One of the potential threats to mussels consists of biological invasions. We intended to investigate the habitat overlap and behavioural differences between native (Unio pictorum, Unio tumidus, Anodonta anatina, Anodonta cygnea) and invasive (Asian Sinanodonta woodiana) unionid bivalves to determine potential sources of competition. Furthermore, we investigated differences between S. woodiana from the established population in artificially heated waters and from the recent population in a natural thermal regime. We used pairwise choice tests on mud, medium, coarse and very coarse sand, mixture of medium and coarse sand, fine, medium and coarse gravel, and observed mussel locomotion and burrowing in preferred and non-preferred substrata. All species generally preferred fine-grained materials. The widest preference range was exhibited by S. woodiana (both populations), whereas A. cygnea was the most selective. The preferences of the cold-water population of S. woodiana were shifted towards coarser materials compared to conspecifics from the heated waters, and highly overlapped with the preferences of the native species. Anodonta cygnea most often moved horizontally and spent the shortest time deeply burrowed. Both Unio species were deeply burrowed for the largest amount of time and the horizontal locomotion of U. tumidus was the lowest among the test species. Sinanodonta woodiana, especially from the heated water population, exhibited relatively weak locomotion (compared to A. cygnea) and burrowing (compared to Unio spp. and A. anatina). Deep burrowing was more common on fine-grained materials. Our results suggest that the native mussels can be threatened by S. woodiana due to their overlapping habitat preferences, potentially hindering habitat separation. However, mobile native mussels may be capable of migrating and avoiding competition. Accumulating knowledge of the biology and ecology of freshwater mussels could contribute to the creation and improvement of conservation plans to protect these threatened animals.

Mean Platelet Volume Has Prognostic Value in Chronic Lymphocytic Leukemia

Purpose

Mean platelet volume (MPV) is a readily accessible and commonly tested hematological indicator. Recent studies revealed a significant impact of MPV on the course and prognosis of many diseases, including some types of cancer, as well as on the incidence of atrial fibrillation and bleeding. The study aimed to perform a retrospective analysis of MPV in terms of time to first treatment (TTFT) and to determine its prognostic value in the group of patients with chronic lymphocytic leukemia (CLL). Moreover, the study includes a retrospective analysis of platelet parameters in patients treated with ibrutinib concerning bleeding and atrial fibrillation.

Patients and Methods

The study included 523 patients with CLL, for 344 the most important cytogenetic aberrations were reported. The Mann–Whitney, Kruskal–Wallis, Kaplan–Meier, chi-squared, log‑rank tests and multivariate Cox proportional hazard regression model were used to analyze collected data.

Results

The receiver operating characteristic curve analysis was performed to identify optimal cut-off value for MPV. The analysis of survival curves showed that in the group of patients with higher values of MPV TTFT was significantly longer than in the group with lower MPV (17.9 vs 36 months, p=0.0015, cut-off value for MPV= 10.4 fl). In multivariate Cox proportional hazard regression model low MPV, the presence of del11q and del13q provided independent prognostic value for TTFT (HR=0.69, 95%-CI, 0.5293 to 0.9081; p=0.0078; HR=1.76, 95%-CI, 1.3000 to 2.3882, p=0.0003, HR=0.74, 95%-Cl, 0.5674 to 0.9588, p=0.0229, respectively). In the group treated with ibrutinib, 59 patients had no significant correlation between MPV level and the incidence of therapy complications, although in the group of patients with low MPV there was a tendency for more frequent occurrence of atrial fibrillation (p=0.259).

Conclusion

Low MPV values are associated with unfavorable prognosis and might represent a novel, independent prognostic factor in CLL.

Expression and variability of lipid metabolism genes in intracranial aneurysm

The objective of this study was to investigate the association between mRNA expression and single nucleotide polymorphisms (SNPs) of the ATP-binding cassette transporter (ABCA1) gene, apolipoprotein A1 (APOA1) gene, low-density lipoprotein (LDLR) gene and RNA gene located in the CDKN2B-CDKN2A cluster (CDKN2B-AS1) involved in lipid metabolism and the occurrence of intracranial aneurysm (IA). Fifty three IA patients, and 27 controls (IA-free) were enrolled in this study and were genotyped for seven single nucleotide polymorphisms. Increased expression of the LDLR gene in IA patients was observed. The A/G genotype and the A allele of the c. -113G>A polymorphism of the APOA1 gene were associated with increased occurrence of IA (ORs 12.36 and 14.14, respectively), while the G/G genotype and G allele showed the opposite tendency (ORs 0.06 and 0.07, respectively). We also detected that the A/A-G/A combined genotype of the c. -113G>A - APOA1 and g.46859A>G - LDLR SNPs was associated with a decreased occurrence of IA. Moreover, the A/G-G/G combined genotype of the c.656G>A - ABCA1 and c. -113G>A - APOA1 was associated with a decreased occurrence of IA. The results of our study suggest the association between expression and variability of lipid metabolism genes and occurrence of IA.

Temperature and pressure dependence of the luminescence of Eu(2+)-doped fluoride crystals Ba(x)Sr(1-x)F(2) (x = 0, 0.3, 0.5 and 1): experiment and model

This paper summarizes experimental evidence of anomalous luminescence in Eu(2+)-doped fluoride crystals Ba(x)Sr(1-x)F(2) (x = 0, 0.3, 0.5 and 1). Luminescence, luminescence excitation spectra and luminescence kinetics obtained at ambient and high hydrostatic pressure at various temperatures are discussed. Hydrostatic pressure was shown to cause a redshift of normal [Formula: see text] emission and anomalous luminescence. The experimental data shows the existence of temperature- and pressure-induced spectral transformations where the anomalous luminescence is replaced by normal emission of Eu(2+) centers. We present a model that predicts a strong electron-lattice coupling of the trapped excitons as well as the pressure effect of the spectral transformation from anomalous to normal emission.

Measurement of the in-medium K0 inclusive cross section in pi(-) -induced reactions at 1.15 GeV/c

The K0 meson production by pi(-) mesons of 1.15 GeV/c momentum on C, Al, Cu, Sn, and Pb nuclear targets was measured with the FOPI spectrometer at the Schwer-Ionen-Synchrotron accelerator of GSI. Inclusive production cross sections and the momentum distributions of K0 mesons are compared to scaled elementary production cross sections and to predictions of theoretical models describing the in-medium production of kaons. The data represent a new reference for those models, which are widely used for interpretation of the strangeness production in heavy-ion collisions. The presented results demonstrate the sensitivity of the kaon production to the reaction amplitudes inside nuclei and point to the existence of a repulsive KN potential of 20+/-5 MeV at normal nuclear matter density.

The influence of NMDA, a potent agonist of glutamate receptor, on behavioral activity of rats with experimental hyperammonemia evoked by liver failure

The study was designed to investigate the effects of NMDA receptor agonist on the behavioral activity in rats with experimental hyperammonemia. The experiments were performed on adult male Wistar rats. Experimental hyperammonemia was induced by intraperitoneal injections of tioacetamide (TAA, 200 mg/kg) for three consecutive days. Rats treated with saline (0.9%) served as control. Stimulation of the NMDA glutamatergic receptor was evoked by ip. injection of agonist N-methyl-D-aspartate acid (NMDA) in a dose of 30 mg/kg thirty minutes before experiments. Memory motivated affectively was evaluated in the passive avoidance responses. The speculative influence of the treatment on anxiety and motor activity was tested in elevated plus-maze and in open field respectively. To show change of NMDA receptor function after various doses of agonist, the seizures evoked by N-methyl-D-aspartate acid was carried out. This experiment showed that with rise of dose of NMDA time to appear of convulsions was contracted in rats with hyperammonemia as well as in control rats. Dose of NMDA caused convulsions was three times as less in rats with hyperammonemia than dose in control. Time of duration of convulsions was proportional to applied dose of NMDA and it lengthened with rise of agonist's dose in both groups of studied animals. Furthermore, we observed that NMDA increased motor activity of control rats in open field test, but not in rats with hyperammonemia (treated tioacetamide). Hyperammonemia did not have significant influence on motor activity and on a passive avoidance latency. The NMDA given in control and in hyperammonemia, increased acquisition, consolidation and recall of a passive avoidance responses. Moreover, NMDA had anxiogenic-like profile in elevated plus-maze. In rats with hyperammonemia NMDA had no influence on locomotor activity but it significantly increased memory in a passive avoidance responses. Furthermore, we observed that reactivity of NMDA glutamate receptor in rats with hyperammonemia was higher than in control rats.

2R,4R-APDC influence on hypoxia-induced impairment of learning and memory processes in passive avoidance test

We investigated the effects of 2R,4R-APDC, a selective group II metabotropic glutamate receptor (II mGluR) agonist, on certain behaviors in rats subjected and non-subjected to hypoxia. Short-term hypoxia was used as a model of experimentally induced amnesia. 2R,4R-APDC given intracerebroventricularly (icv) at doses of 1 mumol and 100 nmol decreased the number of crossings and rearings in the open field, impaired acquisition and consolidation but improved retrieval in the passive avoidance tests. It also shortened the time spent in open arms and prolonged the time spent in closed arms, reduced the number of open and closed arms entries in an elevated "plus" maze, which is a measure of anxiety. Four-minute hypoxia (2% O(2), 98% N(2)) retrieval of conditioned responses, and exhibited an anxiogenic effect in the elevated "plus" maze in rats, i.e. it reduced the time spent in open arms and the number of entries to closed and open arms. 2R,4R-APDC effect on locomotor and exploratory activity was not changed after hypoxia, i.e. we observed inhibition of motility. This agonist of II mGluRs used at both doses before hypoxia significantly improved acquisition and retrieval, and had dual effect on consolidation, viz. at a dose of 1 mumol, it impaired this process and at a dose of 100 nmol it improved it. In the elevated "plus" maze, rats pretreated with 2R,4R-APDC and then subjected to hypoxia shortened the time spent in open arms and prolonged the time spent in closed arms, reduced the time spent in open arms, i.e. the drug exhibited anxiogenic effect. We conclude, therefore, that 2R,4R-APDC itself impaired acquisition and consolidation, enhanced retrieval but in rats undergoing hypoxia, it improved acquisition, retrieval and when used at the dose of 100 nmol enhanced consolidation. 2R,4R-APDC had beneficial effect in hypoxia-induced memory impairment in passive avoidance test.

Nuclear stopping from 0.09A to 1.93A GeV and its correlation to flow

We present a complete systematics (excitation functions and system-size dependences) of global stopping and side flow for heavy ion reactions in the energy range between 0.09A and 1.93A GeV. For the heaviest system, Au+Au, we observe a plateau of maximal stopping extending from about 0.2A to 0.8A GeV with a fast drop on both sides. The degree of stopping, which is shown to remain significantly below the expectations of a full stopping scenario, is found to be highly correlated to the amount of side flow.

Azimuthal dependence of collective expansion for symmetric heavy-ion collisions

Detailed studies of the azimuthal dependence of the mean fragment and flow energies in the Au+Au and Xe+CsI systems are reported as a function of incident energy and centrality. Comparisons between data and model calculations show that the flow energy values along different azimuthal directions could be viewed as snapshots of the fireball expansion with different exposure times. For the same number of participating nucleons more transversally elongated participant shapes from the heavier system produce less collective transverse energy. Good agreement with Boltzmann-Uehling-Uhlenbeck calculations is obtained for a soft nuclear equation of state.

The role of ionotropic receptors of glutaminic acid in cardiovascular system. A. The influence of ionotropic receptor NMDA agonist - 1R,3R-ACPD and antagonist - DL-AP7 on the systemic pressure in rats

The aim of our study was to estimate the involvement of the peripheral N-methyl-D-aspartate receptors in regulation of cardiovascular function. For this purpose we examined the effects of intravenous injection of the agonists - NMDA (0.025; 0.05 and 1.0 mg/kg iv) and 1R-3R-ACPD (0.025; 0.05 and 1.0 mg/kg iv) - and antagonist of NMDA receptors DL-AP7 (0.02; 0.07 and 0.2 mg/kg iv). To determine if the effects of NMDA come from central or peripheral action we observed the effect during blockade of autonomic ganglion by using the nicotinic receptor antagonist - chlorisondamine (1.25 mg/kg iv). Administration of NMDA in three doses evoked slight hypotension after injection of the medium dose, 0.05 mg/kg. In the condition of pretreatment with 1.25 mg/kg chlorisondamine the hypotensive effect of NMDA was markedly reduced, what might suggest that NMDA-induced hypotension raised from the action within the brain. The competetive NMDA receptor antagonist DL-AP7 slightly increased the blood pressure. None of the injected drug had an influence on the heart rate in our in vivo study. It is concluded that the peripherally localized NMDA receptors may take a part in regulation of cardiovascular system, since their stimulation or blockade evoked the changes of systemic pressure.

6-Hydroxydopamine infusions into the structures of mesolimbic dopaminergic system alter the memory enhancing effect of CK-8US and caerulein in rats

The influence of bilateral destruction of dopaminergic endings in the anterior and in the posterior part of nucleus accumbens (NAS) and in the nucleus septi lateralis (NSL), by 6-hydroxydopamine (6-OHDA) infusions, on the facilitatory effect of cholecystokinin-unsulfated octapeptide (CCK-8US) and caerulein (CER) on memory motivated affectively was investigated in male Wistar rats. CCK-8US and CER were given s.c. at the doses of 10 microg/kg and 0.5 microg/kg respectively, immediately after a single learning trial in a passive avoidance situation, ten days after bilateral 6-OHDA lesions (desipramine pre-treatment; 25 mg/kg, i.p.) of these structures. Bilateral 6-OHDA lesions to the anterior and to the posterior part of NAS totally abolished and significantly attenuated, respective, the facilitatory effect of CCK-8US and CER on retention of a passive avoidance behaviour evaluated 24 h later, while bilateral lesions to NSL did not have any influence on it. Moreover, neither, destruction of dopaminergic endings in lesioned structures, nor application of CCK-8US and CER changed the spontaneous psychomotor activity of rats estimated in an "open field" test. These results may indicate that dopaminergic projection to the anterior part of NAS is mainly responsible for the facilitatory effect of CCK-8US and CER on memory motivated affectively.

Baclofen prevents hypoxia-induced consolidation impairment for passive avoidance in rats

We investigated the effects of baclofen, a selective GABA-B receptor agonist, on certain behaviours in rats after short-term hypoxia, as a model of experimentally induced amnesia. Baclofen given intraperitoneally (i.p.) in a dose of 0.25 mg kg(-1) increased the number of crossings and bar approaches in the open field, but was ineffective in the passive avoidance tests; it also shortened the time spent in open arms and reduced the number of open arms entries in an elevated 'plus' maze, being a measure of anxiety. Hypoxia (2% O2, 98% N2) within 4 min profoundly impaired locomotor activity, consolidation and retrieval of conditioned responses, and exhibited a proaxiogenic effect in the elevated 'plus' maze in rats--it reduced the time spent in open arms and the number of entries to closed and open arms. Baclofen's effect on locomotor and exploratory activity was substantially impaired after hypoxia, i.e. rats exhibited a significant reduction in those activities. This agonist of GABA-B receptor used before hypoxia significantly improved consolidation, but had no effect on retrieval. In the elevated 'plus' maze rats pre-treated with baclofen and then subjected to hypoxia prolonged the time spent in open arms, reduced the time spent in closed arms, and increased the number of entries to the arms, i.e. exhibited anxiolytic effect. We conclude, therefore, that baclofen improved consolidation of passive avoidance in rats undergoing hypoxia.

Genotype-dependent proteolytic response of spring wheat to water deficiency

Changes in proteolytic activities in response to water deficiency have been investigated in ten genotypes of spring wheat (Triticum aestivum L.) differing in response to water deficit stress and ability to acclimate. To determine subcellular localization and the type of proteases, mesophyll protoplasts isolated from wheat leaves were purified. Proteolytic activities were assayed using azocasein in the case of vacuolar proteinases at pH 5.0 and 125I-lysozyme in the case of extravacuolar ATP-dependent proteinases at pH 8.2. ATP-dependent proteolytic activity was found to be confined to the extravacuolar fraction while the azocaseinolytic activity to vacuoles. Dehydration increased vacuolar azocaseinolytic activity at both stages of plant development (shooting and heading), but the increase was significantly lower in more tolerant genotypes. The extravacuolar energy-dependent 125I-lysozyme degradation was low at the shooting stage but it was higher in the genotypes with a greater critical water saturation deficit. At the heading phase in the non-acclimated flag leaves ATP-dependent 125I-lysozyme degradation decreased in a genotype-dependent manner, but was enhanced upon acclimation to the same extent irrespective to the genotype ability to acquire dehydration tolerance during acclimation. The results presented indicate that both pathways of protein degradation are interlinked upon dehydration and are genotype dependent.

NMDA receptor antagonists change behavioral activity of rats treated with (S)-4CPG

The effect of (S)-4CPG [(S)-4-carboxyphenylglycine] (25, 50, 100 nmol icv) and the effect of AP-7 (5 nmol icv) or MK-801 (5 nmol icv) on the processes of acquisition, consolidation of conditioned reflexes and locomotor activity were tested in rats. Neither AP-7, MK-801 nor (S)-4CPG given alone changed locomotor activity. MK-801 significantly increased the effects of (S)-4CPG: on crossings at all applied doses, on rearings at 100 nmol, and on bar approaches at 50 nmol of (S)-4CPG. AP-7 enhanced the effects of 50 and 100 nmols of (S)-4CPG on crossings, 100 nmol of (S)-4CPG on rearings in the open field test. Neither AP-7, MK-801 nor (S)-4CPG at doses of 50 and 100 nmols influenced acquisition, but (S)-4CPG given alone at a dose of 25 nmol impaired acquisition. MK-801 impaired the action of 50 and 100 nmols of (S)-4CPG on acquisition. AP-7 only at a dose of 100 nmol inhibited (S)-4CPG-induced acquisition. Neither AP-7, MK-801 nor (S)-4CPG given alone changed consolidation in passive avoidance situation while co-administration of AP-7 and (S)-4CPG at the doses of 50 and 100 nmols, affected this process. The obtained results support our hypothesis concerning the co-operation between group I mGluRs and NMDA receptors in some behavioral tests and the modulating effect of group I mGluRs antagonist on central action of NMDA receptor antagonists.

Examination of the influence of 3,5-DHPG on behavioral activity of angiotensin II

The effects of the class I metabotropic glutamate receptor (mGluR) stimulation on the behavioral activity of angiotensin II (Ang II) was investigated in the present study. The experiments were performed on adult male Wistar rats. Stimulation of the group I of mGluR receptors was evoked by icv injection of (S)-3,5-dihydroxyphenylglycine (3,5-DHPG) at the dose of 0.01 and 1 nmol per rat. Fifteen minutes later, the animals were given icv solution containing 1 nmol of Ang II. Memory motivated affectively was evaluated in passive avoidance and active avoidance responses (CARs). Moreover, the speculative influence of the treatment on anxiety and motor activity was tested in elevated plus-maze and in open field, respectively. We observed that both compounds did not have statistically significant influence on motor activity of rats in open field test. However, 3,5-DHPG at the dose of 0.01 nmol given alone and combined with Ang II tended to increase locomotor activity. 3,5-DHPG, given alone, significantly facilitated consolidation process in a passive avoidance situation (only at the dose of 0.01 nmol) but had no influence on acquisition and recall of information. Examination of the influence of 3,5-DHPG on the acquisition and extinction of CAR proved that it did not alter acquisition and extinction of these responses. In the elevated plus-maze, 3,5-DHPG had anxiogenic-like profile. Ang II, as repeatedly shown before, greatly increased passive avoidance latency, rate of acquisition of CARs and decreased their extinction. On the other hand, Ang II induced anxiolytic-like effect in elevated plus-maze. The pre-treatment of rats with 3,5-DHPG tended to attenuate behavioral effects of the Ang II administration.

AIDA influences behavior in rats pretreated with baclofen

The influence of the blockade of group I metabotropic glutamate receptors (I mGluRs) by AIDA on some behavioral effects of rats pretreated with baclofen, an agonist of GABA-B receptor, was investigated using behavioral tests: the open field, the passive avoidance response and the elevated "plus" maze. Baclofen, applied intraperitoneally (ip) at a dose of 0.25 mg/kg, increased the number of crossed fields and bar approaches in rats in the open field test, and prolonged the time spent in the closed arms, shortened the time spent in the open arms and decreased the number of entries to the open arms in the elevated "plus" maze, but did not affect retrieval in the passive avoidance response. AIDA administered intracerebroventricularly (icv) alone at a dose of 100 nmol reduced crossings and rearings in the open field test, however, it had no effect on retrieval in the passive avoidance situation, nor did it show any influence in the elevated "plus" maze. AIDA given 15 min after baclofen significantly decreased mobility of rats (in the case of crossings to the level observed when AIDA was given alone), i.e. AIDA changed the effects of baclofen in the open field test. We also noted significant impairment of retrieval in rats pretreated with baclofen, which later received AIDA. AIDA significantly reduced the effect of baclofen on this memory process. In the elevated "plus" maze test, AIDA did not influence the behavior of rats pretreated with baclofen in comparison with the group treated with baclofen alone.

Synthesis of new chiral peptide nucleic acid (PNA) monomers

We have synthesised a series of new chiral type I peptide nucleic acid monomers in total yields of 36-53%, derived from Val, Ile, Ser(Bzl), Pro, and Trp, employing convenient procedure.

Influence of nitric oxide on the cardiovascular action of secretin in intact rats. Part A. Does nitric oxide influence the effect of secretin on arterial blood pressure?

The present study aimed to determine the influence of nitric oxide (NO) on the action of secretin in the cardiovascular system in intact rats. The studies involved the in vivo measurements of the systolic (SBP) and diastolic (DBP) blood pressure. The measurements were conducted when NO was absent, which was attained by the use of NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), and when NO was in excess which was obtained by the administration of L-arginine (L-arg), the substrate for NO synthase or exogenous donor of NO, sodium nitroprusside (SNP). Secretin given at the following three doses: 0.75, 1.5 and 3.0 micromoles/kg iv increased SBP and DBP. L-NAME inhibited the slight hypertensive effect of secretin. L-arg abolished the hypertensive effect of the peptide given at the smallest dose, did not change the effect of secretin administered at the medium dose (which did not raise the pressure) and preserved the action of the highest secretin dose. SNP abolished the hypertensive effect of all doses of the peptide. In conclusion, the study has shown that both the lack and excess of NO change the in vivo effect of secretin in intact rats.

Behavioural activity of (S)-3,5-DHPG, a selective agonist of group I metabotropic glutamate receptors

The influence of intracerebroventricular (i.c.v.) injections of (S)-3,5-dihydroxyphenyl-glycine (S)-3,5-DHPG, a selective agonist of group I metabotropic glutamate receptors (mGluRs), on the activity of the central nervous system was examined in male rats. (S)-3,5-DHPG at doses of 25, 50 and 100 nmol significantly attenuated crossings of squares and rearings, but not bar approaches, in an 'open field' test and failed to change apomorphine-induced stereotypy. (S)-3,5-DHPG at the above doses, given immediately after the learning trial, significantly facilitated the consolidation process in a passive avoidance situation, but given before the learning trial and before the retention testing did not have any influence on acquisition and retrieval processes, respectively. Moreover, (S)-3,5-DHPG did not influence recognition memory evaluated in an object recognition test. These results may suggest that activation of group I mGluRs takes part in the consolidation process in affectively-motivated memory, but is probably not necessary for processing of recognition memory, and that (S)-3,5-DHPG memory facilitation seems to be independent of glutamatergic and dopaminergic interaction.

Influence of nitric oxide on the cardiovascular action of secretin in intact rats. Part B. Does nitric oxide influence the effect of secretin on isolated heart function?

The present study was designed to examine the effect of absence or excess of NO on secretin-mediated responses in the isolated heart. This problem was investigated using the modified Langendorff's method. Secretin administered at two higher doses increased the cardiac contraction amplitude (p < 0.05), but did not change the heart rate and coronary outflow. NO was depleted from experimental system by perfusion of the isolated heart with NO synthase inhibitor L-NAME (NG-nitro-L-arginine methyl ester) at 10 microM. It caused a significant decrease in coronary outflow (p < 0.01) and the tendency to bradycardia (p > 0.05) with no change in cardiac contraction amplitude. L-NAME abolished the positive inotropic effect of the medium secretin dose and preserved the inotropic effect of the highest dose of the peptide. It reversed the tendency to decrease coronary outflow induced by secretin (and L-NAME) given separately. To study the effect of NO excess, we applied the substrate for NO synthesis, amino acid L-arginine (L-arg) (100 microM) or exogenous donor of NO--sodium nitroprusside (SNP) (100 microM). Both substances did not affect the isolated heart function. L-arg did not change the effect of secretin, however it abolished non significant decrease in coronary outflow evoked by the highest dose of secretin. SNP preserved the positive inotropic action of the peptide and expressively reversed the negative values of coronary outflow observed after its co-administration with the highest dose of secretin. These results indicate that both the absence and excess of NO change the cardiac effect of secretin in the same direction.

3,5-DHPG influences behavioral effects of baclofen in rats

The role of 3,5-DHPG, an agonist of group I metabotropic glutamate receptors (I mGluRs) in certain behavioral effects of baclofen, an agonist of GABA-B receptor, was assessed. Baclofen, given intraperitoneally (ip) at the dose of 0.25 mg/kg, enhanced the number of crossings and bar approaches in the open field and was ineffective in the passive avoidance tests, and it prolonged time spent in closed arms and shortened time spent in open arms, reduced number of entries into open arms in the elevated "plus" maze, measuring anxiety. 3,5-DHPG given intracerebroventricularly (icv) alone at doses of 0.01, 0.1 and 1.0 nmole did not change locomotor activity in the open field test, except bar approaches: when 3,5-DHPG was given at the dose of 0.01 nmole it enhanced the activity of rats. At doses of 0.01 and 1.0 nmole it improved, but at the dose of 0.1 nmole it significantly impaired retrieval in the passive avoidance situation. All used doses of 3,5-DHPG did not influence the time spent in closed or open arms and the number of entries into open or closed arms in the elevated "plus" maze. 3,5-DHPG, given at the doses of 0.01, 0.1 and 1.0 nmole 10 min after baclofen significantly changed the effect of baclofen decreasing crossings and rearings in the open field, while 3,5-DHPG used at the doses of 0.01 and 1.0 nmole in rats pretreated with baclofen reduced bar approaches. Rats which received baclofen and, 10 min later, 3,5-DHPG at doses of 0.1 and 1.0 nmole, showed significantly improved retrieval in the passive avoidance response. The effect of 3,5-DHPG and baclofen were changed, i.e. 3,5-DHPG and baclofen can cooperate in retrieval process. Coadministration of baclofen and 3,5-DHPG at the dose of 1.0 nmole reduced time spent in the open arms in comparison with baclofen, i.e. this dose of 3,5-DHPG changed the effect of baclofen evaluated in the "plus" maze. Summary, the activation of I mGluR by 3,5-DHPG modulates GABA-B neurotransmission stimulated by baclofen, which is reflected by changing behavioral activity of rats.

The synthesis of a new class of oxytocin antagonists

The synthesis of a new class of oxytocin antagonists, with significantly modified C-terminal part, is described. The chemistry of the Mitsunobu reaction was applied to obtain the key derivatives. In spite of the extensive modifications of previously described compound F792, the peptides retain biological activity as oxytocin antagonists.

Disruption of temporo-entorhinal connections abolishes recognition memory-enhancing effect of angiotensins in rats

In our laboratory, the positive influence of angiotensin II and its 3-7 fragment on learning and memory processes was found to be mediated by excitatory amino acids, because it was abolished by N-methyl-D-aspartate (NMDA) receptor antagonists. The purpose of the present study was to investigate whether bilateral disruption of glutamatergic temporo-entorhinal connections may have an influence on the facilitatory effect of both angiotensin peptides on recognition memory. The bilateral transections of temporo-entorhinal connections were made in 32 male rats 10 days before testing the effect of intracerebroventricular AII or AII(3-7) injection on the recognition of objects evaluated in an object-recognition test. Thirty additional rats served as sham-operated controls. The final analysis was based on 29 lesioned and 26 sham-operated animals. AII and its 3-7 fragment significantly improved object recognition in the sham-operated groups of rats. Bilateral disruption of temporo-entorhinal connections totally abolished the facilitatory effect of both angiotensins on object recognition. Moreover, bilateral disruption of temporo-entorhinal connections significantly attenuated crossings of squares and rearings, without affecting bar approaches and defecation evaluated in an open-field test. These results may suggest that the facilitatory recognition memory effect of AII and AII(3-7) requires a reciprocal glutamatergic connection between the lateral entorhinal cortex and the temporal cortex.

Dopaminergic projection to the central amygdala mediates the facilitatory effect of CCK-8US and caerulein on memory in rats

The involvement of dopaminergic projection to the central amygdala in the facilitatory effect of cholecystokinin unsulphated octapeptide (CCK-8US) and caerulein (CER) on memory motivated affectively was investigated in male rats. CCK-8US and CER were administered subcutaneously at the doses of 10 micrograms kg-1and 0.5 microgram kg-1, respectively, immediately after a single learning trial in a passive avoidance situation, after bilateral 6-OHDA lesions to the central amygdala. Bilateral 6-OHDA lesions to the central amygdala totally abolished the facilitatory effect of CCK-8US and CER on retention of passive avoidance behaviour evaluated 24 h after the learning trial. These results may indicate that the facilitatory effect of CCK-8US and CER on memory motivated affectively is mediated by dopaminergic projection from ventral tegmental area to the central amygdala.

Effects of sulfated cholecystokinin octapeptide and cholecystokinin tetrapeptide in rat behavior after blockade of nitric oxide synthase by L-NAME

This study was conducted to determine what, if any, role L-NAME (inhibitor of nitric oxide synthase) plays in the behavioral effects induced by sulfated cholecystokinin octapeptide CCK-8) and cholecystokinin tetrapeptide (CCK-4) in adult male rats. The motility, stereotypy, anxiety, extinction of conditioned avoidance responses and recall of passive avoidance behavior were estimated. CCK-8 (but not CCK-4) injected intracerebroventricularly (icv) at the dose 0.1 nmole decreased of locomotor activity in the "open field" test. Administration of CCK-8 intensified stereotypy evoked by apomorphine (1 mg/kg, i.p.). The CCK-4 was ineffective in this test. Both, CCK-8 and CCK-4 did not make any significant differences in passive avoidance behavior. Examine the influence of CCK-8 and CCK-4 on the extinction of conditioned avoidance responses (CAR) proved that both peptide tended to facilitate extinction of CAR's. CCK-8 and CCK-4 induced anxiogenic-like effect in the elevated 'plus' maze behavior. Application of L-NAME alone (50 nmole,-icv) decreased of motility and stereotypy behavior in control rats. It was ineffective in a passive avoidance behavior and extinction of CAR's. In elevated 'plus' maze behavior injection of L-NAME, similarly to cholecystokinin, induced anxiogenic-like effect. L-NAME induced of motility decreases in the "open field" test were blocked by injection of CCK-8 and CCK-4. Our results indicate that observed behavioral activity of CCK-8 and CCK-4 (except of influence on motility) is probably independent of NO concentration in the brain.

Similarities and interactions between GABAergic and glutaminergic systems

Harmonious interactions between neurotransmitter systems are important for regulating the activity in the central nervous system (CNS). gamma-Aminobutyric acid (GABA) and glutamate (Glu) are major inhibitory and excitatory neurotransmitters in the mammalian central nervous system. Neuronal excitability, probably synaptic plasticity, cognitive performance, learning and memory processes frequently the results of the balance of GABAergic inhibitory and glutaminergic excitatory inputs.

Baclofen and AII 3-7 on learning and memory processes in rats chronically treated with ethanol

The aim of this study was to determine the possible influence of baclofen, an agonist of the GABA(B) receptor on behavioral activity (recall, acquisition of conditioned reflexes) of angiotensin II fragment 3-7 (AII 3-7) in rats chronically treated with ethanol. Long-term (9 weeks) ethanol intoxication profoundly impaired learning and memory processes in all tests used. The GABA(B) receptor agonist baclofen (0.75 mg/kg i.p.) did not influence exploratory and motor activity in the control rats, but we observed a tendency (without significance) to decrease the psychomotor activity in the alcohol-intoxicated groups of animals, when it was injected together with AII 3-7 (2 microg i.c.v.). Baclofen did not influence the retrieval process in the passive avoidance recall, and when it was given together with AII 3-7 did not change the positive action of this fragment in control groups, but significantly enhanced its action in the animals chronically treated with ethanol. Baclofen showed significant improvement of acquisition in the active avoidance test only in the alcohol-intoxicated groups. Baclofen, injected together with AII 3-7, yielded important attenuation action of AII 3-7 in the control groups in the first 3 days of test, but did not produce any changes during the fourth and fifth day of the experiment. Baclofen did not provoke any changes in activity of AII 3-7 (when it was injected together) in the acquisition of the active avoidance test in the alcohol-intoxicated groups of animals.

Bilateral transections of temporo-entorhinal connections attenuate vasopressin improvement of memory in rats

It has been found in our laboratory that the positive influence of vasopressin (AVP) on memory processes is mediated by excitatory amino acids, since it was abolished by NMDA receptor antagonists. The purpose of the present study was to investigate whether bilateral transections of glutamatergic temporo-entorhinal connections may have an influence on the facilitatory effect of AVP on retrieval process of a passive avoidance behaviour. The bilateral transections of temporo-entorhinal connections were made in male Wistar rats 10 days before testing of the influence of intracerebroventricular AVP (1 microgram per rat) injection on memory, evaluated in a passive avoidance task. Although AVP significantly facilitated the retrieval process both in sham-operated and in lesioned groups of rats, bilateral disruption of temporo-entorhinal connections significantly attenuated the facilitatory effect of AVP on the retrieval process. Moreover, bilateral transections of temporo-entorhinal connections failed to affect motor activity, such as crossings of squares, without an influence on rearings and bar approaches evaluated in an open field test. These results may suggest that in the facilitatory effect of AVP on the retrieval process is involved a reciprocal glutamatergic connection between the lateral entorhinal cortex and the temporal cortex.

6-OHDA lesions to amygdala and hippocampus attenuate memory-enhancing effect of the 3-7 fragment of angiotensin II

We have previously shown that facilitatory effect of angiotensin II (AII) on the retrieval of memory is mediated by the dopaminergic system. In the present study, we searched for the influence of the 3-7 fragment of angiotensin II [AII(3-7)] on the retrieval processes in a passive avoidance situation after bilateral 6-OHDA lesions to the central amygdala (CA) and the CA4 field of the hippocampus (HI). AII(3-7) given 15 min before the retention testing, at the intracerebroventricular dose of 1 nmol, significantly prolonged avoidance latencies in sham-operated rats (i.e. improved retrieval of memory for the electric footshock experienced during the learning trial). Bilateral lesions to CA totally abolished, and to HI significantly diminished, this facilitatory effect. An increase of spontaneous locomotor activity in rats lesioned to CA and a decrease in rats lesioned to HI were unlikely to interfere with the cognitive effect of AII (3-7). These results suggest that the anatomical substrate of facilitating retrieval of information activity of AII(3-7) is closely related to the dopaminergic projection from the ventral tegmental area and substantia nigra to CA and HI.

The effect of baclofen and AP-7 on selected behavior in rats

Synaptic plasticity, cognitive performance, learning, and memory appear to be determined by the balance between GABAergic inhibitory and glutaminergic excitatory amino acids (EAA). To evaluate this role of amino acids the effects of baclofen (0.5 mg/kg IP), GABA-B receptor agonist and AP-7 (5 nmol ICV)-NMDA (N-methyl-D-aspartate) receptor antagonist on the processes of retrieval, consolidation of conditioned reflexes, object recognition, and locomotor activity were tested in rats. Neither AP-7 nor baclofen alone changed locomotor activity, but coadministration of AP-7 and baclofen significantly decreased this activity in the open-field test. Neither AP-7 nor baclofen influenced retrieval or consolidation in the passive avoidance situation when administered alone. Significantly prolonged retrieval and consolidation were observed when AP-7 and baclofen were given together. We did not find differences in effects of either AP-7 or baclofen on object recognition, regardless whether administered alone or in combination.

6-OHDA bilateral lesions to the nucleus septi lateralis attenuate vasopressin improvement of recall in rats

The investigation was aimed at investigating whether the dopaminergic projection arriving at the nucleus septi lateralis (NSL) is involved in the facilitatory effect of vasopressin (AVP) on memory retrieval. The bilateral 6-OHDA lesions to the NSL were made in 20 male Wistar rats before testing the intracerebroventricular (i.c.v.) AVP injection on recall in a passive avoidance situation. Eighteen additional rats served as sham-operated controls. Thirty minutes before surgery rats were pre-treated with an intraperitoneal injection of 25 mg kg-1 of desmethylimipramine, an inhibitor of norepinephrine uptake. Sixteen lesioned and 16 sham-operated rats were included in the study. AVP (1 microgram, i.c.v.) given 15 min before the retention testing significantly improved latencies both in lesioned and in sham-operated rats in comparison with the respective i.c.v. saline-injected animals. However, bilateral lesions to the NSL significantly diminished the facilitatory effect of AVP on recall. The insignificant decrease of spontaneous psychomotor activity in rats lesioned to the NSL was unlikely to interfere with the cognitive effect of AVP. These results suggest that dopaminergic projection to the NSL is involved in the facilitatory effect of AVP on the retrieval process in a passive avoidance situation.

Applications of the Mitsunobu reaction in peptide chemistry

The Mitsunobu reaction--the nucleophilic substitution of an alcoholic hydroxyl group mediated by the redox system trialkylphosphine/dialkyl azodicarobxylate--is widely used in the chemistry of biologically active compounds. The paper deals with applications of the Mitsunobu reaction in amino acid and peptide chemistry. The process provides easy access to many unnatural amino acids and derivatives. Since the reaction occurs with complete inversion of the configuration at the carbinol chiral centre, it can be used for the synthesis of diastereoisomers of hydroxy- and tioprolines. Cyclization of beta-hydroxy amino acid containing peptides under Mitsunobu reaction conditions leads to a constrained peptide that mimics the stabilizing reverse turn secondary structure.

Involvement of nitric oxide in cardiovascular effects of cholecystokinin (CCK) in rats

The aim of the present study was determinate the role of nitric oxide (NO) in the action of CCK on arterial blood pressure and function of isolated rat heart. Intravenous administration of NO synthase (NOS) inhibitor-NG-nitro-L-arginine methyl ester (L-NAME-100.0 micrograms/kg) increased arterial blood pressure and abolished the hypertensive effect of CCK (administered in the highest dose: 425.0 pmoles/kg i.v.). Donors NO: L-arginine (L-Arg-100.0 mg/kg i.v.) and sodium nitroprusside (SNP-10.0 micrograms/kg i.v.) decreased arterial blood pressure, the hypotensive effect evoked by SNP was greater than produced by L-Arg. CCK administered with L-Arg evoked hypotension (opposite to the hypertensive effect evoked by CCK). When we used CCK at the higher doses (212.5; 425 pmoles/kg i.v.) simultaneously with L-Arg the hypotensive effect was greater than the hypotensive action evoked by L-Arg alone. Administration of CCK with SNP produced the hypotension (similar as after used SNP and opposite to the hypertensive action of the peptide). CCK (21.25, 42.5, 106.25 pmoles/0.1 ml) increased the cardiac contraction amplitude, the peptide injected in lower doses decreased coronary outflow. CCK had no effect on heart rate. L-NAME (10(-5) M) decreased coronary outflow, tendent to evoke bradycardia (p > 0.05) and the compound did not change the cardiac contraction amplitude of isolated heart. L-NAME abolished the influence of CCK on the function of isolated heart. L-Arg (10(-2) M) did not affect function of isolated heart. L-Arg abolished and when we used with CCK in the highest dose reversed the positive inotropic effect of the peptide and tendent to abolish a lowered coronary outflow evoked by CCK. SNP (10(-4) M) decreased the cardiac contraction amplitude. SNP diminished the positive inotropic effect of CCK and did not change other parameters of isolated heart.

CONCLUSION

NO does not play a role in cardiovascular action of CCK directly, however inhibitor of NO synthase and donors of NO change the influence of the peptide, mainly on the heart. We suggest that the effect is indirectly through catecholamines.

Role of NMDA receptor in the effects of arginine-vasopressin on memory processes

The mechanism of facilitatory action of vasopressin on memory processes, dependent probably on different neurotransmitter systems, remains unclear. We decided to study the interactions between arginine-vasopressin and ionotropic NMDA receptor. We estimated the influence of various antagonists of NMDA receptor on beneficial effect of arginine-vasopressin on consolidation of conditioned avoidance responses and on retrieval of memory in passive avoidance situation. We have shown that effect of vasopressin on consolidation is significantly reduced by noncompetitive antagonist of ion channel in the NMDA receptor--dizocilpine (MK-801) and competitive antagonist of glycine recognization site--HA-966. Distinctly, effect of the peptide on retrieval is decreased by competitive antagonist of glutamate recognition site--AP-7, competitive antagonist of polyamines site-arcaine and noncompetitive antagonist--MK-801. This suggests that NMDA receptor may participate in the action of vasopressin on memory, but it plays different roles in consolidation and retrieval processes.

Behavioral activity of angiotensin II after stimulation of L-arginine/nitric oxide pathway in rats

This study was conducted to determine what, if any, role L-arginine [an endogenous donor of nitric oxide (NO)] plays in the behavioral changes induced by angiotensin II (AII) in rats. The motility, stereotypy, spatial learning performance, learning of conditioned avoidance response and retention of passive avoidance behavior allowing to avoid aversive stimulation were investigated. Saline (0.9% NaCl), AII, L-arginine and AII combined with L-arginine were injected 15 min before the experiment into lateral cerebral ventricles (icv). L-arginine significantly enhanced locomotor activity while the treatment with AIIplus L-arginine reduced number of bar approaches in the open field test. AII, L-arginine and AII combined with L-arginine (but not with D-arginine) significantly accelerated acquisition of conditioned avoidance responses and not significantly improved recall of the passive avoidance. Only L-arginine displayed a tendency to inhibit acquisition of spatial learning on the second day of investigation in the Morris water maze. AII, L-arginine and AII with L-arginine applied immediately before the experiment intensified stereotypy evoked by apomorphine at a dose of 1 mg/kg and amphetamine at a dose of 7.5 mg/kg given intraperitoneally. These results showed that: 1) L-arginine as a donor of NO might be involved in memory and learning processes, 2) overproduction of NO did not change behavioral effects of AII in these experiments.

The participation of nitric oxide in the facilitator effect of arginine vasopressin on memory

In this study we tested the hypothesis that nitric oxide (NO), which function as a novel type of inter-cellular messenger in the central nervous system (CNS) participated in the facilitator effect of arginine vasopressin (AVP) on learning and memory. Recent investigations have provided evidences that inhibition of NO synthesis attenuated the vasodilatation caused by AVP, and inhibited the improvement of learning and memory evoked by angiotensin II. AVP as well as pharmacologically produced increase in endogenous NO facilitates the consolidation of shock avoidance learning. We evaluated the behavioural effects of AVP at dose 1 microgram after the inhibition of NOS by NG-nitro-L-arginine methyl ester (L-NAME) at dose 10 micrograms, and after the injection of endogenous donor of NO -L-arginine- 10 micrograms in the retrieval of passive avoidance situation, and in consolidation of active avoidance responses. The locomotor activity of all investigated drugs was tested in the open field test. AVP facilitated the recall of passive avoidance responses and consolidation of active avoidance responses. Neither the increase of NO concentration after the injection of L-arginine nor the decrease of NO after the inhibition of NOS by L-NAME changed the behavioural effects of AVP. L-arginine increased the psychomotor behaviour and L-NAME decreased the activity of animals in the "open field" test. L-arginine itself improved the consolidation of active avoidance responses. Our results indicate that central action of AVP is probably independent of NO concentration in the brain.

Effect of bicuculline and angiotensin II fragment 3-7 on learning and memory processes in rats chronically treated with ethanol

The aim of this study was to determine the possible influence of bicuculline, the antagonist of GABA-A receptor on behavioral activity (recall, acquisition of conditioned reflexes) of angiotension II fragment 3-7 (A II 3-7) in rats chronically treated with ethanol. Long term (9 weeks) ethanol intoxication profoundly impaired learning and memory processes in all testes used. The GABA-A receptor antagonist bicuculline (0.5 mg/kg ip) did not influence exploratory and motor activity in the control rats, but we observed tendency (without significance) to decrease the locomotor activity, in the alcohol-intoxicated groups of animals, when the drug was injected together with A II 3-7 (2 microgram icv). Bicuculline did not influence retrieval process in passive avoidance recall in both investigated groups, and when the drug was given together with AII 3-7 significantly enhanced its action in the control group and in rats chronically treated with ethanol. Bicuculline significantly improved acquisition in the active avoidance test in the control and alcohol-intoxicated groups. Bicuculline injected together with A II 3-7 significantly decreased its action in the control group. Coadministration of bicuculline with A II 3-7 did not significantly change the activity of A II 3-7 in the acquisition of active avoidance test in the alcohol-intoxicated groups of rats.

The estimation of interactions between arginine-vasopressin (AVP) and NMDA receptors in memory and learning processes

Arginine-vasopressin (AVP) is a neuropeptide which facilitates learning and memory processes. We examinated the participation of NMDA receptors in beneficial effects of peptide. The results of our study show that noncompetitive antagonist of NMDA receptor-MK-801 impairs the effect of AVP on the consolidation of conditioned avoidance responses and antagonist of polyamines site-arcaine reduced advantageous effect of AVP on the retrieval of memory in passive avoidance situation.

The influence of 1S,3R-ACPD on central dopaminergic transmission and recognition memory

1S,3R-ACPD improved learning and memory in a passive avoidance situation. We examined its influence on recognition memory and dopaminergic transmission. The results of our study shown that 1S,3R-ACPD had not influence on recognition memory and diminished dopaminergic transmission.

Dopaminergic projection to the septum mediates facilitatory effect of angiotensins on recognition memory in rats

We have previously reported that the dopaminergic projection from A10 ventral tegmental neurons to the central amygdala is, in part, responsible for the facilitatory effect of angiotensin II (AII) and its 3-7 fragment [AII(3-7)] on the retrieval of information in memory motivated affectively and also on recognition memory. In this study, the influence of both angiotensins, given intracerebroventricularly at the dose of 1 nmol each, in rats lesioned with 6-OHDA to the nucleus accumbens septi (NAS) and to the nucleus septi lateralis (NSL) on recognition memory was evaluated. AII and its 3-7 fragment significantly improved object recognition in sham-operated to NAS and to NSL groups of rats. Bilateral 6-OHDA lesions to NAS totally abolished and to NSL significantly attenuated the facilitatory effect of both angiotensins on object recognition. These results suggest that the dopaminergic projection arriving to the septal structures. NAS and NSL takes part in the facilitatory effect of angiotensins on recognition memory.

Losartan influences behavioural effects of angiotensin II(3-7) in rats

We have previously shown that angiotensin II(3-7) [Ang II(3-7)] stimulates behavioural activity of rats similar to angiotensin II (Ang II). The involvement of AT1 angiotensin receptors in stimulating the behavioural activity of rats, using their selective ligand losartan (DUP 753), was examined. Ang II(3-7), given intracerebroventricularly (i.c.v.) at a dose of 1 nmol, significantly enhanced recall of a passive avoidance behaviour, object recognition, learning of conditioned avoidance responses (CARs) and apomorphine (1 mg kg-1, i.p.) stereotypy. Losartan (1 microgram, i.c.v.) did not alter any of the behaviours except for that measuring anxiety which was diminished both, in peptide treated and in control rats. On the other hand, losartan abolished Ang II(3-7) facilitation of recall of the passive avoidance, object recognition and the increase in apomorphine stereotypy. Losartan did not influence the increased rate of CARs acquisition after the peptide. None of the treatments significantly changed locomotor activity estimated in an open field. These data point to some involvement of AT1 angiotensin receptors in the behavioural activity of Ang II(3-7).

Behavioral activity of 1S,3R-ACPD, an agonist of metabotropic glutamate receptors

The influence of intracerebroventricular (i.c.v.) injections of 1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD), an agonist of metabotropic glutamate receptors, on the activity of the central nervous system was examined in rats. 1S,3R-ACPD at the i.c.v. doses of 100 and 200 nmole significantly decreased apomorphine-induced stereotypy, and at a dose 200 nmole significantly diminished catalepsy caused by haloperidol, two behavioral symptoms controlled mainly by central dopaminergic system. The tested compound had no influence on the locomotor and exploratory activity of rats estimated in open field. 1S,3R-ACPD significantly improved acquisition at the i.c.v. dose of 100 nmole, and consolidation of information at the i.c.v. doses of 100 and 200 nmole. The tested compound had no influence on retention processes in passive avoidance situation. This compound also did not improve recognition memory tested in the object recognition test. These results indicated that 1S,3R-ACPD improved memory motivated affectively but had no influence on recognition memory and the diminished dopaminergic transmission.

Endoproteinase activities in wheat leaves upon water deficit

In wheat leaves acclimated and non-acclimated to water deficit the azocaseinolytic activities of endoproteinases were increased about 7-fold under drought conditions. Under such conditions both the pH dependence profile and the endoproteinase pattern were also changed. The predominant contribution of serine proteinase (about 50% of total endoproteinase activity) remains unaltered in the drought stressed leaves. Cysteine proteinase was induced to the same extent in the drought-stressed leaves irrespective of the acclimation pretreatment, while the contribution of aspartic proteinase was reduced upon water deficit but in the acclimated stressed leaves was as high as in the non-stressed leaves. These changes in the pattern of endoproteinases seem to imply that the water deficiency affects endogenous proteolysis.

Losartan influences behavioural effects of angiotensin II in rats

The role of the angiotensin AT1 receptors in certain behavioural effects of angiotensin II (Ang II), using their selective antagonist losartan (DuP 753), was assessed. Ang II, given intracerebroventricularly (ICV) at the dose of 1 nmole, significantly improved object recognition, learning of conditioned avoidance responses (CARs), and recall of a passive avoidance behaviour. Losartan alone (1 microgram) was ineffective in any test except for the elevated 'plus' maze measuring anxiety which was diminished by the drug, both in peptide treated and in control rats. Losartan, given 5 min before Ang II, abolished improved after the peptide recall of the passive avoidance and object recognition. Losartan did not influence increased after Ang II rate of CARs acquisition. None of the treatments significantly changed behaviour of rats in the open field. The results point to the considerable involvement of the AT1 angiotensin receptors in the cognition improving effects of Ang II. However, unspecific psychoactivity of losartan should also be taken into account.