Effect of chronic administration of antidepressants on the binding of 3H-imipramine with mouse brain synaptic membranes

Subchronic (14 days) administration of chlorimipramine and zimelidine, and a new morpholine derivative produces different effects on 3H-imipramine binding with synaptic membranes of the mouse brain. Chlorimipramine increases the concentration of the binding sites (Bmax), zimelidine raises both the Bmax and the dissociation constant, while the new morpholine derivative does not significantly change these characteristics. It has been demonstrated that the changes in the Bmax that occur during prolonged administration of chlorimipramine depend on the method for the obtaining of membrane brain preparations.     

Mathematical modeling of the spatial distribution of the pollen produced by genetically modified crops

We present and analyze the results of mathematical simulation of pollen spreading from a field sown with genetically modified plants. Factors responsible for genetic isolation of such fields are discussed.     

Differences in the characteristics of opiate and catecholaminergic receptors of the striatum and cerebral cortex of rats of Fisher-344 and WAG/GSto strains may cause differences in reinforced action of morphine]

It has been shown that Fischer-344 rats more than WAG/GSto inbred rats preferred to consume the solution of morphine. In intravenous self-administration testing, Fischer-344 rats had a higher rate of reinforced responses that resulted in morphine infusion. Bmax values for mu- and alpha 2-adrenoreceptors were significantly higher in the cortex of WAG/GSto rats. The sensitivity of the serotonin and dopamine receptors in the cortex and striatum of WAG/GSto rats was lower than that in Fischer-344 rats. These findings suggest that the difference between morphine consumptions in two inbred rat strains may be due to individual genetic patterns determining opioid and catecholamine receptors binding in the brain.     

Effect of chronic use of antidepressants on the state of benzodiazepine receptors in the mouse brain

A study was made of the effect of a two-week administration of chlorimipramine, zimelidine and a morpholine derivative on benzodiazepine receptors of the mouse brain. The animals which received antidepressants demonstrated a significant increase in the binding sites of 3H-flunitrazepam without any changes in the dissociation constant as compared to control. The data on the evoked aggressiveness and latency of tonic corasole convulsions in the antidepressant-treated animals support the functional importance of the discovered changes in benzodiazepine receptors.     

Mathematical model of invasion of mysids (Mysidacea) into the Naroch Lake system

We present a mathematical model of the invasion of mysid into the Naroch Lake system. The model is parameterized with the use of field observation data. We show that the mysid invasion can lead to an increase in the time-averaged fish population size, and to a decrease in the time-averaged rotifer population size.     

Involvement of the adenylyl cyclase signaling system in the action of insulin and mollusk insulin-like peptide

Involvement of the adenylyl cyclase signaling system in the mechanism of action of the mammalian insulin and epidermal growth factor as well as of insulin-like peptide isolated from the bivalve mollusk Anodonta cygnea has been studied. It was shown for the first time that insulin and insulin-like peptide exert in vitro the GTP-dependent stimulating action on the adenylyl cyclase activity. Epidermal growth factor has an analogous effect. Effectiveness of the peptides decreased in the order insulin-like peptide > epidermal growth factor > insulin in the foot smooth muscles of A. cygnea and insulin > epidermal growth factor > insulin-like peptide in the skeletal muscles of rat.     

Isolation, primary structure, and biological and immunological properties of pink and chum salmon insulins

1. Insulins have been isolated from islet tissue of pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon. The primary structure of chum and pink salmon insulins was found to be identical. Compared to the amino acid sequence of human insulin, the salmon insulins under study differed at 14 positions. 2. Biological activity of pink salmon insulin was 83% of that of standard porcine insulin. 3. The immunological properties of fish insulins were investigated in specific radioimmunoassay (RIA) systems, based on porcine and pink salmon insulins. 4. A significant difference in the antigenic determinants of these fish and mammalian hormones was revealed.     

A peptide mimetic targeting trans-homophilic NCAM binding sites promotes spatial learning and neural plasticity in the hippocampus

The key roles played by the neural cell adhesion molecule (NCAM) in plasticity and cognition underscore this membrane protein as a relevant target to develop cognitive-enhancing drugs. However, NCAM is a structurally and functionally complex molecule with multiple domains engaged in a variety of actions, which raise the question as to which NCAM fragment should be targeted. Synthetic NCAM mimetic peptides that mimic NCAM sequences relevant to specific interactions allow identification of the most promising targets within NCAM. Recently, a decapeptide ligand of NCAM--plannexin, which mimics a homophilic trans-binding site in Ig2 and binds to Ig3--was developed as a tool for studying NCAM's trans-interactions. In this study, we investigated plannexin's ability to affect neural plasticity and memory formation. We found that plannexin facilitates neurite outgrowth in primary hippocampal neuronal cultures and improves spatial learning in rats, both under basal conditions and under conditions involving a deficit in a key plasticity-promoting posttranslational modification of NCAM, its polysialylation. We also found that plannexin enhances excitatory synaptic transmission in hippocampal area CA1, where it also increases the number of mushroom spines and the synaptic expression of the AMPAR subunits GluA1 and GluA2. Altogether, these findings provide compelling evidence that plannexin is an important facilitator of synaptic functional, structural and molecular plasticity in the hippocampal CA1 region, highlighting the fragment in NCAM's Ig3 module where plannexin binds as a novel target for the development of cognition-enhancing drugs.