Participation of 5-HT1A-receptors in regulating various types of aggressive behavior

We studied the effects of selective agonists of 5-HT1A receptors 8-OH-DPAT and flesinoxan on aggressive behavior of C57BL/6 male mice in the "resident-intruder" test and on defensive aggression of Norway rats toward man. 8-OH-DPAT (0.4 mg/kg, i.p.) significantly reduced the intermale aggression in mice and defensive aggression in rats (0.1-0.5 mg/kg, i.p.). In the dose of 0.5 mg/kg, flesinoxan inhibited the aggressive behavior in mice. These results suggest that activation of 5-HT1A receptors reduces different kinds of affective aggression. The results are discussed in terms of interaction between the well-known anxiolytic effects of 5-HT1A agonists and their antiaggressive properties.     

Identification of catalytically active groups of lipoxygenase from wheat germ

Catalytically active groups of lipoxygenase in wheat germs have been identified. Blocking of catalytically active groups by specific reagents, dependence of the enzyme activity on pH, enthalpy of ionization of pK1 and pK2, the enzyme photoinactivation allowed to make a conclusion that imidasole and hydroxyl groups take part in lipoxygenase catalytic cycle.     

Modulation of neuronal evoked responses to the medial septal area of hibernating ground squirrels by some neuropeptides after chronic disconnection between septum and preoptico-hypothalamic structures

Effects of some neuropeptides identified in the brain of hibernators (TSKYR, TSKY, DY) and of monoaminergic neurotransmitters (noradrenaline and serotonin) on responses of the medial septal neurons evoked by intraseptal electrical stimulation were analyzed in slices taken from the ground squirrels with chronic basal undercutting of the septum. Despite the elimination of direct contacts with the preoptic area and afferents ascending in the medial forebrain bundle, the neurons retained almost normal level of reactivity and distribution of the reaction types. The neuropeptides effectively modulated neuronal responses of various types, including oligosynaptic short-latency single-spike responses. The latter were strongly facilitated by the neuropeptides. As a rule, changes in the responses to electrical stimulation were independent of the spontaneous activity shifts (in 78% of the tests). It was suggested that the neuropeptides exert a double influence on the septal neurons: direct nonsynaptic effects on the pacemaker potential responsible for the background activity and modulation of synaptic processes. Our experiments showed that descending influences of the septo-hippocampal system are not crucial for the entrance into the hibernation state and its tonic maintenance. The influences of the thermoregulatory--circadian structures of the preoptico-hypothalamic area determine the paradoxically increased latent excitability of septal neurons that allows the septo-hippocampal system to gate external stimuli and organize arousal of the forebrain during hibernation in case of emergency.     

Reserve nutrient substance accumulation in Brassica rapa L. seeds in microgravity conditions (STS-87)

The results of study of Brassica embryo differentiation and reserve nutrient substance accumulation in the seeds were represented. Near resemblance of the spaceflight and around control embryo development was revealed. Different character of the reserve substance accumulation was noted, despite of the morphologic similarity in seeds produced in spaceflight and on the ground. It allows to consider spaceflight embryos morphologically more younger compared to the ground control.     

Correlation between cataleptic freezing and prestimulation inhibition of the startle reflex in rats

In rats of GC strain bred for predisdposition to cataleptic freezing, a significant negative correlation between the duration of freezing and the level of prepulse inhibition (PPI) of the startle reflex, has been found. Besides, in a group of GC rats specific by their "nervousness" and jumpiness, there was also a negative correlation between the duration of freezing and the habituation to the startle reflex. None of this correlation have been found in Wistar rats. Since impairment of the PPI and habituation of the startle reflex is considered to be characteristic of schizophrenia, it is believed than cataleptic freezing in the GC rats may be used as a model of schizophrenic psychopathology.     

Age-specific morphological-functional characteristics of the rabbit's hippocampal neurons during conditioning

Formation of trace rhythm recruitment (an analogue of conditioned time reflex) was studies in CA3 hippocampal neurons of alert young (less than one year), old (54-65 months), and very old rabbits after a prolonged (10-20 min) electro-cutaneous stimulation of a forelimb with the frequency of 0.5-1 Hz. Comparative analysis of neuronal spike activity in young and old rabbits showed that in the late ontogeny the number of spontaneously active neurons was significantly decreased, the proportion of slowly firing neurons increased, the interspike intervals and intervals between spike groups became longer, the number of spikes in a group reduced. The ability of hippocampal neurons to acquire and reproduce the rhythm of the previous stimulation declined with age. No appropriate rhythms were found in neurons of very old animals. A nonspecific increase in neuronal baseline activity was observed in old rabbits after the stimulation. Deterioration of morphological structures of hippocampal neurons and glial cells may explain the impairment of mnestic processes in late ontogeny.     

Characterization of expressed pigmented core light harvesting complex (LH 1) in a reaction center deficient mutant of Blastochloris viridis

The utility of photosynthetically defective mutants in the purple photosynthetic bacterium Blastochloris viridis (formerly Rhodopseudomonas viridis)was demonstrated with construction of a reaction-center deficient mutant, LH 1-H. This LH 1-H mutant has a photosynthetic apparatus in which most of the puf operon genes were deleted, resulting in an organism containing only the genes for the light harvesting polypeptides and the H subunit of the reaction center. This B. viridisstrain containing a truncation of the puf operon was characterized by gel electrophoresis, lipid-to-protein ratio analysis, optical spectroscopy, electron paramagnetic resonance and transmission electron microscopy. Optical and electron paramagnetic resonance spectroscopies revealed no photoactivity in this LH 1-H mutant consistent with the absence of intact reaction centers. Electron paramagnetic resonance evidence for assembled LH 1 complexes suggested that the interactions between light harvesting polypeptide complexes in membranes were largely unchanged despite the absence of their companion reaction center cores. The observed increase in the lipid-to-protein ratio was consistent with modified interactions between LH 1s, a view supported by transmission electron microscopy analysis of membrane fragments. The results show that B. viridis can serve as a practical system for investigating structure-function relationships in membranes and photosynthesis through the construction of photosynthetically defective mutants. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of Metabolites of γ-Aminobutyric Shunt on Activities of NAD- and NADP-Isocitrate Dehydrogenases and Aconitate Hydratase from Higher Plants

We studied the influence of metabolites of -aminobutyric shunt of the tricarboxylic acid cycle on the activities of aconitate hydratase (EC.4.2.1.3) as well as NAD- and NADP-specific isocitrate dehydrogenases (EC.1.1.1.41 and EC.1.1.1.42, respectively) using purified enzyme preparations from pea leaves (Pisum sativum L.) and maize scutellum (Zea mays L.). -Aminobutyric acid and succinate proved to have no significant effect on these enzymes, while 0.1–0.2 mM glutamate markedly activated NADP isocitrate dehydrogenase from both sources, especially at unsaturating concentrations of the substrate. Succinic semialdehyde stimulated the activities of aconitate hydratase and NADP isocitrate dehydrogenase. The obtained data point to a similar pattern of the effect of intermediates of -aminobutyric shunt on the studied enzymatic activities for both photosynthetic tissues (pea leaves) and those with acidifying, transport, and digestive functions (maize scutellum). However, the absence of pronounced control effects of most metabolites on the studied enzymes allows us to assign them to a relatively inert pool of metabolites.