The role of defensin NP-1 in restoring the functions of an injured nerve trunk.

This report presents results from studies on the actions of neutrophil defensin NP-1 on the initial stage of regeneration of the lesioned sciatic nerve in rats. The effects of defensin on the growth rate and functional characteristics of regenerating nerve fibers were assessed by recording total action potentials 21 days after transection and microsurgical suturing of the nerve. These experiments showed that defensin increased the rate of growth of regenerating nerve fibers by 30%: the distance over which nerve spike conductivity was restored in the lesioned nerve increased from 7.2 +/- 1.2 (control) to 10.5 +/- 0.8 mm (experiment) from the suturing site (p < 0.05). In addition, an increase in the excitation conduction rate along the regenerating nerve fibers by 20% compared with control was observed. Overall, the results provide evidence for the positive effects of defensin on restoration of the functions of the lesioned nerve trunk.

[Defensin NP-1 in restoration of the injured nerve trunk functions].

The effect of Defensin NP-1 on early phase of injured sciatic nerve regeneration was studied in rats. Using the technique of AP compound recording performed within 21 days after the nerve trunk cutting with subsequent microsurgical nerve suture, the rate of fibres growth was shown to increase by 30% following Defensin treatment: the distance to which the nerve impulse conductivity through injured nerve fibres was restored has extended from 7.22 +/- 1.2 mm (control) to 10.5 +/- 0.8 mm (Defensin treatment) from the suture site (p < 0.05). Moreover, the conducting capacity of the regenerating nerve fibres has risen by 20% as compared with control values. The findings suggest a positive effect of Defensin on restoration of injured peripheral nerve in rats.

Recovery of mechanoreception at the initial stage of regeneration of injured sciatic nerve in rats in conditions of central axotomy of sensory neurons.

The ability of injured afferents of the rat sciatic nerve to regenerate in conditions of damage to their connections with the central nervous system (CNS) as a result of extensive rhizotomy was studied. Recording of spike activity from single nerve fibers demonstrated that rhizotomy, performed simultaneously with nerve injury, had virtually no effect on the initiation of regenerative processes in sensory nerve fibers. The first clear signs of reinnervation of the skin of the foot by decentralized nerve fibers was seen 30 days after nerve injury, which agrees with data obtained in standard conditions, i.e., without rhizotomy. Decentralization of sensory neurons was found to lead to increases in the threshold of perception of a mechanical stimulus in intact and regenerating receptors. However, regenerating receptors showed a significantly more marked decrease in stimulus sensitivity.

[Effect of central axotomy of sensory neurones on the mechanoreception recovery in initial regeneration of the injured sciatic nerve in rats]. / Vosstanovlenie mekhanoretseptsii na nachal'noi stadii regeneratsii povrezhdennogo sedalishchnogo nerva krysy v usloviiakh tsentral'noy aksotomii sensornykh neironov.

No apparent effect of lumbar dorsal rhizotomy performed simultaneously with the peripheral nerve injury, has been revealed on the triggering of regeneration of sensitive nerve fibers. Re-innervation of the foot skin by either decentralized regeneration of nerve fibers or those sustaining their connections with the central nervous system (CNS), has been shown to start 30 days after surgery. Using the recording of impulse activity of a single nerve fibre, the mechanical thresholds of decentralized regenerating receptors were found to be significantly higher as compared to the thresholds of the regenerating receptors sustaining their connections with the CNS. The findings suggest that afferent nerve fibers and mechanical receptors formed on the periphery, continue functioning after decentralization and sustain their regenerative capacity after injury. However, in marked contrast, the decrease in sensitivity of regenerating receptors is more pronounced.

Activity of foot skin mechanoreceptors and afferent nerve fibres in the adult rat sciatic nerve are altered after central axotomy of sensory neurons.

The functional properties of skin mechanoreceptors were examined in the hind foot of normal rats in comparison with animals subjected to dorsal rhizotomy. Evoked nerve impulses were recorded from afferent nerve fibres of the tibial nerve. The decentralized mechanoreceptors displayed evidence of autonomous functioning, but with several abnormalities as compared to normal animals. There was a decreased sensitivity to mechanical stimulation and a lower adaptive capacity as a consequence of rhizotomy. The underlying mechanism is suggested to be a loss of central trophic support because of the interrupted link between the central nervous system and the sensory ganglion cell periphery. The findings indicate that mechanical receptors continue functioning under conditions when sensory impulses flow cannot reach postsynaptic target neurons in the central nervous system, but stop at the level of the primary sensory neuron.

Effect of tetrapeptide cortagen on regeneration of sciatic nerve.

Intramuscular injection of 10 microg/kg cortagen to rats during 10 days after transsection and suturing of the sciatic nerve increased the growth rate and conduction velocity in the regenerating nerve fibers by 27% and 40%, respectively.

[Functional characteristics of foot skin mechanoreceptors and afferent nerve fibers of the sciatic nerve after central axotomy of sensory neurons]. / Issledovanie funktsional'nykh kharakteristik retseptorov kozhi stopy i afferentnykh nervnykh volokon sedalishchnogo nerva krysy posle tsentral'noi aksotomii sensornykh neironov.

The activity of mechanoreceptors was studied in normal rats' hindfoot and compared with that of rhizotomised animals. Evoked nerve impulses were recorded from afferent fibres of the n.tibialis. A possible autonomous functioning of decentralised mechanoreceptors, even though in an altered fashion, was shown. The registered shifts comprised a decrease in sensitivity to mechanical stimulation and lower adaptive properties. The findings suggest that the underlying mechanism involves a probable lack of trophic interaction leading to interruption of a link between the CNS and the peripheral nervous system.

[Effect of RB-101, inhibitor of enkephalin degrading enzymes, on recovery of conductivity of the injured sciatic nerve in rats]. / Vliianie RB-101, blokatora fermentov, razrushaiushchikh énkefaliny, na vosstanovlenie provodimosti povrezhdennogo sedalishchnogo nerva krysy.

A dose-dependent effect of the enkephalinase RB-101 on functional recovery of the rat injured sciatic nerve was revealed. The findings suggest the enkephalines participation in regulation of regenerative processes in peripheral nerves.

[Lactate dehydrogenase activity and isoenzyme spectrum in the transplanted sensory and sympathetic ganglia of the rat]. / Aktivnost' i izofermentnyi spektr laktatdegidrogenazy transplantirovannykh sensornykh i simpaticheskikh gangliev krysy.

Total activity, isoenzyme pattern of lactate dehydrogenase (LDH), morphological peculiarities of normal and transplanted in the mesentery for 1-7 and 30 days dorsal root and superior cervical sympathetic ganglia of the adult rats, were analysed. About 30% neurons in sensory ganglia and 5% in sympathetic ganglia were viable 30 days after transplantation. Total LDH activity was 3 times higher in normal sympathetic ganglia compared with that in spinal ganglia. Transplantation leads to a slight rising in total LDH activity in sensory root ganglia and to a slight fall in sympathetic ganglia. Five fractions of LDH in normal sensory ganglia and four fractions in sympathetic ganglia were revealed. Significant rising of M4 isoenzyme activity was characteristic of both sensory and sympathetic ganglia after transplantation for 7 days. Functional significance of the changes observed is discussed.

[Nature of the hyperpotassic composition of the medium surrounding individual tissue mechanoreceptors]. / O prirode giperkalievogo sostava sredy, okruzhaiushchei odinochnye tkanevye mekhanoretseptory.

The ouabain effect on potassium concentration in the Pacini corpuscle fluid was studied using continuous perfusion of cat's mesenteric receptors with ouabain in Ringer's bicarbonate solution. To check the solution penetration into the corpuscles, Na36Cl and (G-3H)-ouabain were used. 2 . 10(-2) mM ouabain reduced (K+) in corpuscle fluid. The high potassium concentration in Pacini corpuscle fluid seems to be due to Na+--K+-ATPase system.