Fatigue-induced Fos immunoreactivity within the lumbar cord and amygdala decreases after С60 fullerene pretreatment.

The fundamental aspects related to the mechanisms of action of C60 fullerene nanoparticles on the level of the central nervous system in different experimental conditions are still unclear. Electrophysiological investigation and immunohistochemical techniques of c-fos expression were combined to determine which neural elements within the lumbar segments and in the central nucleus of the amygdala (CeA) are activated under skeletal muscle fatigue development with prior application of C60 fullerenes (dissolved in dimethyl sulfoxide and in distilled water, FDS). After high-frequency electrical stimulation of the triceps surae muscle, the main fatigue-related increases in the c-Fos expression level were registered ipsilaterally within lamina 1 and 5 of the lumbar segments and within the contralateral capsular part of the CeA. C60 fullerene pretreatment in animals with subsequent electrical stimulation induced a distinct (2-4 times) decrease in the level of Fos immunoreactivity in the observed structures in comparison with only fatigue-induced rats. It can be supposed that FDS, as antioxidant compound, can decrease the concentration of free radicals in fatigued tissue and reduce the transmission intensity of nociceptive information from muscles to the spinal cord and amygdala, thereby changing the level of c-Fos expression within the lumbar segments and CeA.

C60 fullerenes increase the intensity of rotational movements in non­anesthetized hemiparkinsonic rats.

The effect of C60 fullerene aqueous colloid solution (C60FAS) on the intensity of long­lasting (persisting for one hour) rotational movements in non­anesthetized rats was investigated. For this purpose, an experimental hemiparkinsonic animal model was used in the study. Rotational movements in hemiparkinsonic animals were initiated by the intraperitoneal administration of the dopamine receptor agonist apomorphine. It was shown that a preliminary injection of C60FAS (a substance with powerful antioxidant properties) in hemiparkinsonic rats induced distinct changes in animal motor behavior. It was revealed that fullerene­pretreated animals, in comparison with non­pretreated or vehicle­pretreated rats, rotated for 1 h at an approximately identical speed until the end of the experiment, whereas the rotation speed of control rats gradually decreased to 20-30% of the initial value. One can assume that the observed changes in the movement dynamics of the hemiparkinsonic rats after C60FAS pretreatment presumably can be induced by the influence of C60FAS on the dopaminergic system, although the isolated potentiation of the action of apomorphine C60FAS cannot be excluded. Nevertheless, earlier data on the action of C60FAS on muscle dynamics has suggested that C60FAS can activate a protective action of the antioxidant system in response to long­lasting muscular activity and that the antioxidant system in turn may directly decrease fatigue­relate d changes during long­lasting muscular activity.

Fos immunoreactivity in the intermediolateral nucleus induced by tendon vibration of the m. triceps surae in rats pretreated with a nitric oxide blocker or precursor.

We investigated neuronal activation of the rat intermediolateral (IML) nucleus of the thoracolumbar spinal cord, initiated by Achilles tendon vibration, after intramuscular (m. triceps surae) administration of 7­nitroindazole (7­NI) or L­arginine (LA). The spindle afferent response to vibratory stimuli induced a distinct bilateral increase in the activation of c­Fos immunoreactivity in the spinal neurons in three groups of rats (tendon­vibrated, tendon­vibrated + 7­NI and tendon­vibrated + LA). The T5/T13 segments in tendon­vibrated +7­NI animals showed the highest increase of Fos­immunoreactive neurons. This increase was two times higher than that in tendon only­vibrated control rats and endon­vibrated + LA animals. The highest mean number of labelled neurons were observed in the IML nucleus and in layers 4 and 7 of the T5-L3 segments in tendon­vibrated and tendon­vibrated + 7­NI animals, and in the IML nucleus and layer 4 in tendon­vibrated + LA rats. The highest mean number of activated neurons was found ipsilaterally in the IML nucleus of the T5/T13 segment. These results indicate that decreased nitric oxide release after injection of 7­NI was accompanied by a potentiation of the early c­fos gene expression induced by muscle proprioceptive activity within the thoracolumbar region of the rat spinal cord. Thus, enhanced c­Fos immunoreactivity in the IML nucleus indicated that the sympathetic nervous system can exert a direct influence on the muscle spindles.

NADPH-diaphorase reactivity and Fos-immunoreactivity within the ventral horn of the lumbar spinal cord of cats submitted to acute muscle inflammation induced by injection of carrageenan.

The NADPH-diaphorase activity and Fos-immunoreactivity within the ventral horn of the lumbar spinal cord were studied in cats with acute unilateral myositis following injection of carrageenan into the m.m. gastrocnemius-soleus. In carrageenan-injected cats maximum in the mean number of intensely stained NADPH-diaphorase reactive (NADPH-dr) neurons was found in lamina VII (+100%) and VIII (+33%) of the contralateral ventral horn of the L6/L7 segments as compared with control animals. The maximumal level of Fos-immunoreactivity was registered in the same laminae with ipsilateral predominance (39.3±4.6 and 7.6±0.9 cells), in comparison with the contralateral side (13.6±0.8 and 5.5±0.6 cells, respectively; P<0.05). We also visualized low-intensely stained and double labelled (Fos immunoreactive+low-intensely stained NADPH-dr) multipolar and fusiform Renshaw-like cells (RLCs) within the ventral horn on both sides of the L6/L7 segments in carrageenan-injected cats. We visualized the double labelled (Fos-ir+NADPH-dr) multipolar and fusiform Renshaw-like cells (RLCs) within the ventral horn on both sides of the L6/L7 segments in carrageenan-injected cats. A significant difference in the mean number of RLCs was recorded between the ipsi- and contralateral sides in the lamina VII (13.6±2.5 vs. 4.9±0.7 cells, respectively). We suppose that activation of inhibitory RLCs in ipsilateral lamina VII could be directed on attenuation of activation of motoneurons during muscle pain development. Our study showed that a significant contralateral increase in the number of NADPH-dr cells is accompanied by an ipsilateral increase in c-Fos expression in lamina VII. These data may suggest that NADPH-dr neurons of the contralateral ventral horn through commissural connections also involved in the maintenance of the neuronal activity associated with acute muscle inflammation. It is also hypothesized, that during acute myositis, plastic changes in the ventral horn activate the processes of disinhibition due to an increase in the number of NADPH-d-reactive neurons in the spinal gray matter.