[Pretective action of peptide pro-gly-pro on electrophysiological characteristics of cultured hippocampal neurones during excitotoxic damage].

Electrophysiological characteristics of hippocampal neurones cultured with Pro-Gly-Pro peptide were studied using glutamate excitotoxisity model (excitotoxic damage was induced by 100 mkM glutamate application during 5 min). It was found that negative changes in neurones cultured with 10 mcM Pro-Gly-Pro were less prominent if compared with control ones. Culturing with the peptide significantly affected the following parameters: resting potential (-55 +/- 4 mV in control; -29 +/- 6 MV after glutamate application; -38 +/- 5 MV cultured after glutamate application), action potential amplitude (91 +/- 4; 65 +/- 5; 84 +/- 5 mV), duration (4,3 +/- 0,4; 9,5 +/- 1,6; 5,2 +/- 0,7 ms), depolarization (56 [38, 84]; 27 [21, 35]; 46 [28, 62] MV/Ms) and repolarization (-29 [-38, -27]; -20 [-21, -18]; -29 [-33, -22] M(V)/MS) rates.

[Characteristics of quantal release of glutamate and GABA in synapses between retinal ganglion cells and superior colliculus neurons in coculture].

We investigated features of quantal release of glutamate and GABA in synapses between retinal ganglion cells (RGC) and superior colliculus (SC) neurons in coculture using dual patch-clamp technique. The main quantal characteristics of neurotransmitters release were defined on the basic of quantal analysis. Number of released quanta distributions for both neurotransmitters were corresponded to the binomial law.

[Changes in the kinetics of calcium signals in response to high frequency stimulation in the cultured hippocampal neurons].

Dynamic changes in the intracellular free Ca2+ concentration ([Ca2+]i) were studied in hippocampal cultured neurons using fluorescent Ca(2+)-indicator dye Indo-1 and somatic whole-cell recordings. During the tetanus stimulation Ca(2+)-transient increased their amplitude up to a steady-state level during repetitive stimulation. We identified two groups of neurons based on Ca-signal dynamics after the end of stimulation: the first group (n = 24) with the monoexponential decay of [Ca2+]i direct after the end of the tetanus; the second group (n = 32) with the monoexponential delayed [Ca2+]i decay after the end of the tetanus, the duration of delay varied from 1 to 27 s and depended on duration and frequency of stimulation.

[Electrical properties of retinal ganglion cells of rats with streptozotocine-induced diabetes].

On isolated retinal preparation from STZ-induced diabetic rats in whole-cell configuration the basic electrical properties of retinal ganglion cells (RGC) were studied. It was shown that on 8th week after STZ maximal depolarization-induced firing frequency is reduced and decay time constant of high-frequency stimulation-induced calcium signals is increased as compared to controls. The data obtained suggest functional changes in RGC of STZ-induced diabetic rats, possible mechanisms of such changes are discussed.

[Pre- and postsynaptic expression mechanisms of long-term depression in rats glutamatergic primary afferent synapses on dorsal horn spinal cord neurons in co-culture].

In co-culture of dorsal root ganglion (DRG) and dorsal horn (DH) neurons we studied the long-term depression (LTD) caused by 5 sec(-1) low-frequency stimulation (LFS) of DRG neurons. Dual whole-cell patch clamp recording in the pairs of DRG and DH neurons was used. The monosynaptic AMPA-receptor mediated eEPSC initiated in DH neurons by LFS of DRG neurons were analyzed.

[Calcium signaling induced by tonic firing in the rat eye retinal ganglion cells].

On rat retinal preparation in whole-cell mode retinal ganglion cells (RGC) tonic firing induced calcium signals were recorded and their modulation by Kv3 potassium channels was studied. RGC depolarization with 500 ms current steps caused tonic action potentials (AP) generation and development of calcium signals which amplitude depended quite linearly on mean AP frequency with mean slope 1.4 +/- 0.

[Characteristics of sensory neurotransmission in co-culture of neurons from the dorsal root ganglion and dorsal horn spinal cord in rats].

We examined properties of chemical neurotransmission at the level of primary afferent inputs into spinal cord with the new easy-to-use in vitro model of contiguously-cultivated dissociated both the dorsal root ganglion neurons (DRG) and the dorsal horn spinal cord neurons (DHSC) from newborn rats. The results of our studies showed the presence of excitatory and inhibitory DRG neurons synapses on the cells of DHSC. The excitatory afferent signaling in such synapses was mediated by presynaptic release of glutamate and a following activation of both NMDA- and non-NMDA-receptor subclasses.

[Effect of 4-aminopyridine-sensitive potassium current on high frequency tonic firing of the rat retinal ganglion cells].

High frequency firing properties of the rat retinal ganglion cells and role of 4-AP-sensitive potassium current in firing generation were studied using whole cell patch-clamp techniques. Potassium channel blocker 4-AP (0,2 mM) reduced depolarization-evoked firing rate by 62% (from 50 +/- 5, n = 12 to 19 +/- 2 Hz, n = 7). Single action potential parameters were affected: half-width was increased by 133% (from 1,2 +/- 0,1, n = 12 to 2,8 +/- 0,3 ms, n = 7), decay slope was decreased by 63% (from 102 +/- 11, n = 12 to 38 +/- 7 mV/ms, n = 7) and afterhyperpolarization amplitude by 83% (from 18 +/- 2, n = 12 to 3 +/- 2 mV, n = 7).

[Nonuniform distribution and contribution of the P- and P/Q-type calcium channels to short-term inhibitory synaptic transmission in cultured hippocampal neurons].

In the present study, we investigated the sensitivity of GABAergic short-term plasticity to the selective P- and P/Q-type calcium channels blocker omega-agatoxin-IVA. To block the P-type channels we used 30 nM of this toxin and 200 nM of the toxin was used to block the P/Q channel types. The evoked inhibitory postsynaptic currents (eIPSC) were studied using patch-clamp technique in whole-cell configuration in postsynaptic neuron and local extracellular stimulation of single presynaptic axon by rectangular pulse.

[The role of N-type high-voltage-activated calcium channels in plasticity regulation of inhibitory synaptic transmission in cultured hippocampal neurons].

Now it is clear that N-type Ca2+ channels contribute to synaptic transmission at many of CNS synapses. However, it is not known whether presynaptic N-type Ca2+ channels contribute to short-term synaptic plasticity (STP) mediated by GABA release at inhibitory synapses of cultured hippocampal neurons. We studied the sensitivity of GABAergic paired pulse depression (PPD) as a common form of STP to selective N-type high-voltage-activated Ca2+ channels blocker omega-conotoxin (omegaCgTx).

[Synaptic responses and intraganglionic connections of rat superior cervical ganglia neurons].

The rat superior cervical ganglion (SCG) neurones demonstrate responses on the threshold stimulation of the cervical sympathetic nerve, extrinsic (ECN) and intrinsic (ICN) carotid nerves. Both antidromic and synaptic responses were evoked by antidromic stimulation of ECN and ICN. The synaptic responses of each neuron differ by great variability amplitudes of the excitatory postsynaptic potentials and the currents, the rise time and the time constant decay of the postsynaptic current.

[Voltage-activated potassium channels of the inhibitory interneurons of the hippocampus in culture].

Potassium channels make up the largest family of voltage-activated channels and play a key role in maintenance of cell excitability and in transmission of information within the nervous system. The aim of this work was to find out the specific subtypes of voltage-activated potassium channels peculiar to GABAergic interneurons of rat hippocampal culture. It was shown that total depolarization-evoked outward potassium current in any interneuron studied had the activation threshold about -50 mV.

[Electrophysiological properties of inhibitory neurones in cultured dissociated hippocampal cells].

Electrophysiological properties of inhibitory (GABAergic) neurones were studied in dissociated hippocampal culture using simultaneous whole cell recordings from pairs of monosynaptically coupled neurons. Reliable identification of GABAergic neuron was performed by presence of monosynaptic inhibitory currents at postsynaptic cell in response to action potentials at stimulated cell. It was shown that GABAergic neurons in hippocampal culture are divided in two groups by their firing characteristics: first type generates action potentials at high frequency in response to injection of current (duration 0.

[Ionic currents responsible for activation of isolated retinal ganglion cells].

Ionic currents responsible for excitability of retinal ganglion cells (RGC) freshly isolated from eyes of adult rats were studied. Kutward potassium currents in RGC represented by populations of slow inactivating and non-inactivating currents. Inward sodium currents were completely blocked by extracellular application of 0.