Role of vagus nerves in antiarrhythmic effect of DAGO in acute myocardial ischemia

Acute experiments on cats show that DAGO, a selective μ-opiate receptor agonist, elicits a pronounced antiarrhythmic effect in ischemia-induced arrhythmias. The protective effect of DAGO is observed only under conditions of intact parasympathetic innervation of the heart and apparently depends on then. vagus activity and stimulating effect of DAGO on acetylcholine release. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 10, pp. 377–379, October, 1997     

Comparison of Changes in Glutamate Levels in the Nucleus Accumbens of the Rat Brain during Food Consumption in Conditions of Blockade of Dopamine D1 and D2 Receptors

The effects of blockade of D₁ and D₂ dopamine receptors in the nucleus accumbens on changes in glutamate levels in the intercellular space of this structure during food consumption were studied in Sprague–Dawley rats by intracerebral microdialysis combined with HPLC. These experiments showed that food consumption was accompanied by decreases in glutamate levels in the intercellular spaces of the nucleus accumbens. Blockade of D₁ dopamine receptors with SCH-23390 (0.01 mM) produced no changes in the dynamics of glutamate release during food consumption. Food consumption in conditions of blockade of D₂ dopamine receptors with raclopride (0.01 mM) induced increases in glutamate levels. These data suggest that glutamate levels during food consumption are controlled by the dopaminergic system of the nucleus accumbens, mediated by D₂ but not D₁ dopamine receptors.     

Studies of the Effects of Monoamines on Orexinergic Neurons in the Hypothalamus of Rat Embryos

Neuroscience and Behavioral Physiology - Hypothalamic orexinergic neurons are involved in controlling various body functions, particularly energy balance, feeding behavior, wakefulness, and...     

Correlation between the Sizes of Individual Parts of Mauthner Neurons in Goldfish and Their Integral Function after Enucleation of the Eye

Three-dimensional reconstruction was used to study the structural correlates of significant increases in the activity of Mauthner neurons (MN) deafferented after unilateral enucleation of the eye evidenced by an irreversible shift in motor asymmetry in goldfish towards the “blind” side. The results showed that in some cases, the dominance of the MN correlated significantly with a decrease in the volume of its ventral dendrite, while in others, it correlated with an increase in the sizes of the body and the lateral dendrite. Both structural signs appeared to result from local redistribution of the neurotransmitter balance due to the tension of the undamaged sensory inputs. Overall, the results demonstrated that prolonged adaptive changes in the behavior of the fish may be regulated by specific morphological rearrangements of MN at the level of individual dendrites acting via feedforward and feedback mechanisms.     

Primary culture of mouse embryonic spinal cord neurons: cell composition and suitability for axonal regeneration studies

Objective: Primary culture is an effective experimental model to study molecular mechanisms that drive axonal regeneration after central nervous system injury. However, the culture of spinal cord (SC) cells remains poorly characterized. Here, we have analyzed the cell composition of a primary SC culture during its maturation.

Methods: Primary cell culture was prepared from mouse embryo spinal cords. After 2, 7, and 14 days of cultivation, the cells were fixed and stained with antibodies against β3-tubulin, nestin, crmp1, SMI-32, DCC or GFAP. We counted percentage of cells positive for the mentioned markers and measured the length of cell processes.

Results: We found that β3-tubulin and nestin were both expressed at day 2 of culture in vitro. Surprisingly (given the use of differentiation-supporting culture medium), the number of nestin+ cells has significantly increased during the first week of cultivation. The GFAP+ cells appeared only at the seventh day in vitro, and their fraction increased during the following cultivation. At 14 day in vitro, SC culture contained cells that expressed the markers typical of commissural and motor neurons. At this age, the neurons had the ability to repair injured neurites after mechanical damage.

Conclusion: Primary culture of SC cells is a dynamically developing cell population that contains all main types of SC cells and is capable of self-repair. Therefore, the culture of mouse embryonic SC cells represents an adequate experimental model for studying cellular and molecular processes taking place in SC neurons after axonal damage in the absence of external inhibitors.     

Role of σ-opiate receptors in development of ischemic arrhythmias

In acute experiments on anesthetized cats, the selective σ-opiate receptor agonist DSLET has a pronounced antiarrhythmic effect on ischemic heart rhythm disturbances. This effect is probably related to inhibition of the sympathetic heart rhythm regulation, because the antifibrillation effect of DSLET is not mediated via the vagus nerves, but on the other hand DSLET considerably modulates cardiac adrenoreactivity. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 2, pp. 164–167, February, 1999.     

Effects of opioid peptides on the development of ischemic cardiac arrhythmias under conditions of partial sympathetic denervation and laser irradiation

The effects of intravenous administration of different opioid peptides on the development of ischemic cardiac arrhythmias under conditions of intraatrial laser irradiation (λ=632.8 nm) were studied in cats with transected cardiac branches of the right stellate ganglion and preserved sympathetic innervation of the ischemized area. Ischemia was caused by occlusion of the circumflex branch of the left coronary artery. It was found that the protective effects of dalargin were most powerful when sympathetic influences on the ischemic area were intestified by laser irradiation. Under these conditions DAGO showed more pronounced antiarrhythmic effects than DSLET. Translated fromByulleten' Eksperimental'noi Biologii i Medistiny, Vol. 127, No. 4, pp. 374–377, April, 1999