D. I. Peregud

Amyloid-β (25-35) increases activity of neuronal NO-synthase in rat brain

Nitric oxide (NO) is a free radical with multiple functions in the nervous system. NO plays an important role in the mechanisms of neurodegenerative diseases including Alzheimers disease. The main source of NO in the brain is an enzymatic activity of nitric oxide synthase (NOS). The aim of the present study was to analyze the expression and activity of both neuronal (nNOS) and inducible (iNOS) isoenzymes in the cerebral cortex and hippocampus of rats after intracerebroventricular administration of amyloid-beta (A beta) peptide fragment A beta(25-35). NADPHd histochemistry as well as immunohistochemistry were also used to investigate nNOS and iNOS expression in rat brain. The data presented here show that A beta(25-35) did not influence levels of nNOS or iNOS mRNA or protein expression in both structures studied. A beta(25-35) activated nNOS in the cerebral cortex and hippocampus without effect on iNOS activity. A beta(25-35) decreased the number of NADPHd-expressing neurons in the neocortex, but it did not significantly influence the number NADPHd-positive cells in the hippocampus. The peptide had no effect on the number of nNOS containing cells. We hypothesize that increased synthesis of NO induced by A beta(25-35) is related to qualitative alterations of nNOS molecule, but not to changes in NOS protein expression.

Synthesis and study of NOS-inhibiting activity of 2-N-acylamino-5,6-dihydro-4H-1,3-thiazine

The synthesis and results of in vitro and in vivo testing of 2-N-acetylamino-, 2-N-benzoylamino-,2-N-cyclohexanecarbonylamino-, and 2-N-(1-adamantanecarbonyl)amino-5,6-dihydro-4H-1,3-thiazines for NOS-inhibiting activity have been described.

Elevation of BDNF Exon I-Specific Transcripts in the Frontal Cortex and Midbrain of Rat During Spontaneous Morphine Withdrawal is Accompanied by Enhanced pCreb1 Occupancy at the Corresponding Promoter

Abstract Brain-derived neurotrophic factor (BDNF) is believed to play a crucial role in the mechanisms underlying opiate dependence; however, little is known about specific features and mechanisms regulating its expression in the brain under these conditions. The aim of this study was to investigate the effects of acute morphine intoxication and withdrawal from chronic intoxication on expression of BDNF exon I-, II-, IV-, VI- and IX-containing transcripts in the rat frontal cortex and midbrain. We also have studied whether alterations of BDNF exon-specific transcripts are accompanied by changes in association of well-known transcriptional regulators of BDNF gene—phosphorylated (active form) cAMP response element binding protein (pCreb1) and methyl-CpG binding protein 2 (MeCP2) with corresponding regulatory regions of the BDNF gene. Acute morphine intoxication did not affect levels of BDNF exons in brain regions, while spontaneous morphine withdrawal in dependent rats was accompanied by an elevation of the BDNF exon I-containing mRNAs both in the frontal cortex and midbrain. During spontaneous morphine withdrawal, increased associations of pCreb1 were found with promoter of exon I in the frontal cortex and promoters of exon I, IV and VI in the midbrain. The association of MeCP2 with BDNF promoters during spontaneous morphine withdrawal did not change. Thus, BDNF exon-specific transcripts are differentially expressed in brain regions during spontaneous morphine withdrawal in dependent rats and pCreb1 may be at least partially responsible for these alterations.

Changes in anxiety in abstinence correlate with the state of the nigrostriatal system in the rat hippocampus

Opiate dependence results from impairments of neuronal plasticity, i.e., so-called aberrant neuroplasticity, formation of which involves long-term structural-functional rearrangements persisting even during drug abstinence. Nitric oxide (NO) is involved both in mediating the effects of opiates and in the mechanisms of some types of neuroplasticity, so NO may potentially take part in the development of psychopathological processes on opiate withdrawal. The present study addressed measures of the nitrergic system (nitric oxide synthase (NOS) activity and nitrite and nitrate (NOx−) concentrations) in areas of the rat brain; anxiety was also assessed, in terms of behavioral measures in the elevated plus maze, during morphine withdrawal. NOS activity was found to increase by day 3, while the NOx− concentration was increased by day 6 of withdrawal, these changes being seen only in the hippocampus. At six days after morphine withdrawal, rats showed more entries into the open arms of the elevated plus maze and remained in these arms longer. Correlations were found between measures of the NO system in the hippocampus and the behavior of the animals in the maze. These results suggest that changes in the activity of the nitrergic system in the hippocampus represent one of the molecular mechanisms impairing the behavior of animals in abstinence.

Neurobiological Bases of Predisposition to the Development of Opiate Addiction

The range of individual differences in sensitivity to the pharmacological effects of psychoactive substances, especially opiates, is large. Understanding of the processes that control individual differences in the development of opiate addiction is very important for the identification of risk factors and development of effective prophylactics and therapeutic programs. We review the neurobiological bases of the predisposition to the development of opiate addiction. We also focus on the perspectives of studies of the role of the brain nitrergic system in the individual sensitivity to development of opiate addiction.

Neonatal proinflammatory stress induces accumulation of corticosterone and interleukin-6 in the hippocampus of juvenile rats: Potential mechanism of synaptic plasticity impairments

Infectious diseases in early postnatal ontogenesis can induce neuroinflammation, disrupt normal central nervous system development, and contribute to pathogenesis of cerebral pathologies in adults. To study long-term consequences of such early stress, we induced neonatal proinflammatory stress (NPS) by injecting bacterial lipopolysaccharide into rat pups on postnatal days 3 and 5 and then assessed the levels of corticosterone, proinflammatory cytokines and their mRNAs, and neurotrophins and their mRNAs in the hippocampus and neocortex of the one-month-old animals. Long-term potentiation (LTP) was studied in hippocampal slices as an index of synaptic plasticity. NPS-induced impairments of LTP were accompanied by the accumulation of corticosterone and IL-6 in the hippocampus. In the neocortex, a decrease in exon IV BDNF mRNA was detected. We suggest that excessive corticosterone delivery to hippocampal receptors and proinflammatory changes persisting during brain maturation are among the principal molecular mechanisms responsible for NPSinduced neuroplasticity impairments.

Effects of early neonatal proinflammatory stress on the expression of BDNF transcripts in the brain regions of prepubertal male rats

Early postnatal proinflammatory stress may evoke behavioral impairments in adulthood; however, the underlying mechanisms are still elusive. The brain-derived neurotrophic factor (BDNF) plays a key role in neuroplastic changes in health, as well as in pathology. The BDNF gene is transcribed to exon-specific mRNAs and the pattern of their expression depends on stimulus. We suggested that disturbances of the exonspecific BDNF mRNA expression in the brain regions after stress induced by proinflammatory stimuli in the early postnatal period could be one of the underlying mechanisms of consequent behavioral impairments. Thus, the aim of the study was to examine the effects of proinflammatory stress in early postnatal ontogeny on the BDNF polypeptide content and the patterns of expression of the BDNF gene in the neocortex and hippocampus of prepubertal male rats. The proinflammatory stress was induced by the subcutaneous administration of bacterial lipopolysaccharide (LPS) to rat pups on postnatal days 3 and 5, while BDNF expression was studied in 36-day-old rats. The BDNF polypeptide content was estimated using an enzyme-linked immunosorbent assay, while a quantitative polymerase chain reaction followed by reverse transcription was used to detect the exon-specific BDNF mRNA expression. The levels of BDNF and its transcripts, containing the common exon IX were similar in the control and LPS-treated rats. In the rats treated with LPS, the level of BDNF mRNA containing exon IV was lower in the neocortex but not in the hippocampus. No changes in the expression of the transcripts containing exons I and VI were observed in any of the brain structures studied. We suggest that specific alterations in BDNF expression may be involved in susceptibility to the development of behavioral impairments of animals subjected to early proinflammatory stress.

Molecular modeling, X-ray diffraction analysis, and the study of iNOS inhibitor activity of 3-imino-2,4-diazabicyclo[3.3.1]nonan-1-ol hydrochloride

AbstractiNOS-Inhibitor activity of 3-imino-2,4-diazabicyclo[3.3.1]nonan-1-ol hydrochloride was predicted basing on molecular modeling and was confirmed by experiments in vitro. The results of the study by XRD analysis of the molecular and crystal structure of this compound are reported.

Effects of Single Injections of Brain-Derived Neurotrophic Factors into the Midline Ventral Tegmental Area on the Reinforcing Properties of Morphine

The strong positive reinforcing effect of opiates is regarded as a trigger for the development of pathological dependence, though the neurobiological basis of this process has received little study. Published data suggest that brain-derived neurotrophic factor (BDNF) in the lateral ventral tegmental area (VTA) can modulate the positive reinforcement produced by morphine. The involvement of BDNF in the midline VTA in mediating positive reinforcement has not previously been studied. The aim of the present work was to assess the influences of single injections of BDNF into the midline VTA in rats on the acquisition and reproduction of a conditioned place preference reaction (CPPR) induced by morphine. The CPPR was developed over eight sessions (one session per day). Rats received alternating doses of i.p. morphine (10 mg/kg) or isotonic saline, combining administration with corresponding conditioned contextual stimuli. Recombinant human BDNF (0.75 μg) or solvent (phosphate-buffered saline, PBS) were given as single doses into the midline VTA one day before or one day after the conditioning phase. During testing of the CPPR, animals spent statistically significantly longer periods of time (p < 0.05) in the sector associated with morphine administration than in the sector associated with administration of physiological saline. This is evidence that morphine had a reinforcing action, inducing preference for the place the animals occupied after administration. Single injections of BDNF into the midline VTA given before but not after the conditioning phase eliminated the differences between the times spent in the sector associated with morphine and physiological saline administration (p > 0.05). It can therefore be suggested that single doses of BDNF into the midline VTA before the conditioning phase can weaken the reinforcing properties of morphine.

Specific Activity Features in the Forced Swim Test: Brain Neurotrophins and Development of Stress-induced Depressive-like Behavior in Rats

Selective vulnerability or resilience to mood disorders is related to individual differences or personality. In the present study forced swim test (FST) was used as a tool for division of male rats according to their immobility behavior. The animals were subjected to a chronic unpredictable mild stress (CUS). Depressive-like behavior and modifications in brain neurotrophin system of were examined after CUS exposure. The low immobile (LI) and high immobile (HI) rats demonstrated elusive differences in expression of BDNF ExVI mRNA and TrkA mRNA which was higher in the hippocampus and frontal cortex, respectively, of HI rats as compared to LI animals. Exposure to CUS resulted in development of depressive-like phenotype and increased anxiety in both subgroups; however, immobility in FST specifically decreased in the initially HI animals. In hippocampus of stressed LI rats, the contents of total BDNF mRNA decreased. In hippocampus of stressed HI rats, the content of TrkA mRNA increased whereas in frontal cortex, the content of BDNF exon I mRNA decreased in both LI and HI rats. The levels of BDNF ExIX and ExI as well TrkB mRNAs were higher in the hippocampus of HI rats as compared to LI rats. In general, the response of hippocampus to CUS was much more expressed as compared to frontal cortex. Thus, initially different stress coping strategies of rats in the FST (HI, LI) were associated with the development of similar behavioral phenotypes after chronic unpredictable stress; however, these phenotypes were associated with different alterations in neurotrophin systems of the brain.