Water-soluble pristine C60 fullerenes attenuate isometric muscle force reduction in a rat acute inflammatory pain model

BACKGROUND

Being a scavenger of free radicals, C₆₀ fullerenes can influence on the physiological processes in skeletal muscles, however, the effect of such carbon nanoparticles on muscle contractility under acute muscle inflammation remains unclear. Thus, the aim of the study was to reveal the effect of the C₆₀ fullerene aqueous solution (C₆₀FAS) on the muscle contractile properties under acute inflammatory pain.

METHODS

To induce inflammation a 2.5% formalin solution was injected into the rat triceps surae (TS) muscle. High-frequency electrical stimulation has been used to induce tetanic muscle contraction. A linear motor under servo-control with embedded semi-conductor strain gauge resistors was used to measure the muscle tension.

RESULTS

In response to formalin administration, the strength of TS muscle contractions in untreated animals was recorded at 23% of control values, whereas the muscle tension in the C₆₀FAS-treated rats reached 48%. Thus, the treated muscle could generate 2-fold more muscle strength than the muscle in untreated rats.

CONCLUSIONS

The attenuation of muscle contraction force reduction caused by preliminary injection of C₆₀FAS is presumably associated with a decrease in the concentration of free radicals in the inflamed muscle tissue, which leads to a decrease in the intensity of nociceptive information transmission from the inflamed muscle to the CNS and thereby promotes the improvement of the functional state of the skeletal muscle.

Medical Fuzzy-Expert System for Assessment of the Degree of Anatomical Lesion of Coronary Arteries

BACKGROUND

Today, cardiovascular diseases cause 47% of all deaths among the European population, which is 4 million cases every year. In Ukraine, CAD accounts for 65% of the mortality rate from circulatory system diseases of the able-bodied population and is the main cause of disability. The aim of this study is to develop a medical expert system based on fuzzy sets for assessing the degree of coronary artery lesions in patients with coronary artery disease.

METHODS

The method of using fuzzy sets for the implementation of an information expert system for solving the problems of medical diagnostics, in particular, when assessing the degree of anatomical lesion of the coronary arteries in patients with various forms of coronary artery disease, has been developed.

RESULTS

The paper analyses the main areas of application of mathematical methods in medical diagnostics, and formulates the principles of diagnostics, based on fuzzy logic. The developed models and algorithms of medical diagnostics are based on the ideas and principles of artificial intelligence and knowledge engineering, the theory of experiment planning, the theory of fuzzy sets and linguistic variables. The expert system is tested on real data. Through research and comparison of the results of experts and the created medical expert system, the reliability of supporting the correct decision making of the medical expert system based on fuzzy sets for assessing the degree of anatomical lesion of the coronary arteries in patients with various forms of coronary artery disease with the assessment of experts was 95%, which shows the high efficiency of decision making.

CONCLUSIONS

The practical value of the work lies in the possibility of using the automated expert system for the solution of the problems of medical diagnosis based on fuzzy logic for assessing the degree of anatomical lesion of the coronary arteries in patients with various forms of coronary artery disease. The proposed concept must be further validated for inter-rater consistency and reliability. Thus, it is promising to create expert medical systems based on fuzzy sets for assessing the degree of disease pathology.

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 7‑nitroindazole (7‑NI) or L‑arginine (LA). The spindle afferent response to vibratory stimuli induced a distinct bilateral increase in the activation of c‑Fos immunoreactivity in the spinal neurons in three groups of rats (tendon‑vibrated, tendon‑vibrated + 7‑NI and tendon‑vibrated + LA). The T5/T13 segments in tendon‑vibrated +7‑NI animals showed the highest increase of Fos‑immunoreactive neurons. This increase was two times higher than that in tendon only‑vibrated control rats and endon‑vibrated + 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 tendon‑vibrated and tendon‑vibrated + 7‑NI animals, and in the IML nucleus and layer 4 in tendon‑vibrated + 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 7‑NI was accompanied by a potentiation of the early c‑fos gene expression induced by muscle proprioceptive activity within the thoracolumbar region of the rat spinal cord. Thus, enhanced c‑Fos immunoreactivity in the IML nucleus indicated that the sympathetic nervous system can exert a direct influence on the muscle spindles.

[NADPH-DIAPHORASE REACTIVITY IN THE VENTRAL HORN OF THE FELINE SPINAL CORD DURING ACUTE MUSCLE INFLAMMATION]

The aim of this research was to reveal the changes in the NADPH-d reactivity in the lumbal spinal cord (L6/L7) of cats with unilateral acute myositis of the mm. gastrocnemius-soleus after intramuscular injections of carrageenan. The effect of unilateral muscle inflammation was expressed in a significant increase in the number of NADPH-d-reactive neurons in ipsilateral and contralateral intermediate (lamina VII; 17.62 ± 2.7 and 20.67 ± 13.3) and medial (lamina VIII; 7.3 ± 1.9 and 6.0 ± 2.1 respectively) zones of the ventral horns. However, a clear decline of the reactive cells was recorded on the ipsilateral side within the area around the central canal (lamina X). An increase in the NADPH-d reactivity within the ventral horns on both sides on the spinal cord and the induction of such reactivity (contralaterally) in large multipolar neurons localized in the dorsal part of the intermediate zone were revealed in cats with unilateral acute muscle inflammation. It is hypothesized, that during acute myositis, plastic changes in different layers of the dorsal and ventral horns activate the processes of disinhibition due to an increase in the number of NOS-containing/NADPH-d-reactive neurons in the spinal gray matter.

7-Nitroindazole enhances c-Fos expression in spinal neurons in rats realizing operant movements

The expression of c-Fos and NADPH-diaphorase reactivity (NADPH-dr) in the cervical spinal cord was studied in adult male Wistar rats that realized operant reflexes after inhibition of neuronal nitric oxide synthase. Fos-immunoreactive neurons were visualized immunohistochemically in the C6/C7 spinal segments in the control, realized operant movements animals, and/or 7-nitroindazole (7-NI) injected rats. The mean numbers of immunoreactive interneurons and motoneurons (per section) were significantly greater in the Nucleus proprius (+240%) and motor nuclei (+600%) in rats of the 7-NI-pretreated and operant reflex realized group than in the isolated operant reflex realized group. Our study showed intensive staining of NADPH-dr axon terminals on the somata and initial parts of dendrites of motoneurons in experimental rats when the disodium salt of malic acid was added to the staining solution. Suppression of NO release is associated with potentiation of neuronal activation induced by descending supraspinal and proprioceptive signaling within the spinal cord.

[Food-procuring stereotype movements is accompanied by changes of c-Fos gene expression in the amygdala and modulation of heart rate in rats]

The distribution of Fos-immunoreactive (Fos-ir) and NADPH Diaphorase reactive (NADPH-dr-) neurons in the different subnuclei of amygdala and insular cortex (on the level -2,12 to -3,14 mm from bregma), and the associated changes of heart rate (HR) in intact, food-deprivated and executed food-procuring movements of rats were studied. In comparison with other groups of animals, the mean number of the Fos-ir neurons in the central nucleus of amygdala (Ce) and the insular cortex (GI/DI) at all studied levels was significantly greater in the executed food-procuring movements in rats. The main focus of localization of the Fos-ir neurons was found in lateral part of the Ce (58.5 +/- 1.9 units in 40-microm-thick section) at the level -2.56 mm. The mean number of Fos-ir neurons was significantly greater also in the lateral and capsular parts of the Ce. The mean number of Fos-ir neurons in the GI/DI was 165.5 +/- 3.2 cells in section. The number and density of NADPH-d reactive neurons was not significantly different in the brain structures of all animal groups studied. The double stained neurons (Fos-ir + NADPH-dr) were registered in medial, basolateral, anterior cortical amygdaloid nuclei and substantia innominata (SI) in rats after realization food-procuring movements. It was found that realization of food-procuring movements by the forelimb during repeated sessions was accompanied with the gradual decline of mean values of the HR (from 5% to 12% of control level) with subsequent renewal of them to the initial values (tonic component). The analysis of dynamics of the HR changes during realization of separate purposeful motion has shown the transient period of the HR suppression (500 ms), which coincided with the terminal phase of grasping of food pellet (phasic component). We suggest that the revealed focuses of localization of Fos-ir neurons in the lateral and medial subregions of amigdaloid Ce and also GI/DI, and SI testified that these structures of brain are involved in generation of the goal-directed motions. Direct projections of these subnuclei (and hypothalamus) to the cardiovascular centers of the medulla determine the associated regulation of the cardiovascular system function in the period of realization of the goal-directed motions in animals.

[Laminar distribution of the active spinal cord neurons during the feeding-related stereotyped movements in the rat]

The comparative study of expression of early c-fos-gene (marker of neuronal activation) and NADPH-diaphorase reactivity (NADPH-dr) was performed in the cervical spinal cord of rats in the control (intact) animal, in the state of starvation and after realization of long-lasting (repeated 4 to 12 times per minute for 30 min) motivated stereotyped food-procuring forelimb movements. In comparison with control rats; in the starving rats or rats showed forelimb movement to reach-to-grasp the food, the number of Fos-immunoreactive (Fos-ir) cells in the dorsal and ventral horns of a 40-microm-thick slice was significantly greater (P < 0.05). The number of Fosir neurons in the starving state clearly exceeded that in the most layers after realization of movements. Increase of Fos immunoreactivity in the superficial (2i, 3) and deeper (4, 5) layers of the dorsal horn was initiated, evidently, by signals from peripheral and supraspinal structures. We also found labelled cells within layers 6-8, and 9 demonstrating the activity of interneurons and motoneurons directly involved into generation of operant forelimb movements. According to our data, high density of NADPH-dr/NO-generating neurons in the C6/C7 segments are observed in the substance gelatinosa (layer 2i) and layers 7 and 10. NADPH-dr cells and Fos-ir neurons were intermixed within the layers but did not demonstrate double-labelling. It is possible to suggest that NADPH-dr/NO-generating cells of the spinal cord did not operate under realization of the studied operant reflexes, which did not include nociceptive component.

NADPH-diaphorase activity and neurovascular coupling in the rat cerebral cortex

The distribution of NADPH-diaphorase-reactive (NADPH-dr) neurons and neuronal processes in the cerebral cortex and basal forebrain and their association with parenchymal vessels were studied in normal adult rats using NADPH-d histochemical protocol. The intensely stained cortical interneurons and reactive subcortically originating afferents, and stained microvessels were examined through a light microscope at law (x250) and high (x630) magnifications. NADPH-dr interneurons were concentrated in layers 2-6 of the M1 and M2 areas. However, clear predominance in their concentration (14 +/- 0.8 P < 0.05 per section) was found in layer 6. A mean number of labeled neurons in auditory (AuV), granular and agranular (GI, AIP) areas of the insular cortex was calculated to reach 12.3 +/- 0.7, 18.5 +/- 1.0 and 23.3 +/- 1.7 units per section, respectively (P < 0.05). The distinct apposition of labelled neurons to intracortical vessels was found in the M1, M2. The order of frequency of neurovascular coupling in different zones of the cerebral cortex was as following sequence: AuV (31.2%, n = 1040) > GI (18.0%, n = 640) > S1 (13.3%, n = 720) > M1 (6.3%, n = 1360). A large number of structural associations between labeled cells and vessels in the temporal and insular cortex indicate that NADPH-d-reactive interneurons can contribute to regulation of the cerebral regional blood flow in these areas.

Coupling of c-fos expression in the spinal cord and amygdala induced by dorsal neck muscles fatigue

c-fos gene expression in the cervical spinal cord and amygdala was examined in anaesthetized rats following muscle fatigue caused by intermittent high-rate (100 s(-1)) electrical stimulation of the dorsal neck muscles (m. trapezius and m. splenius). Fatigue-related increases in c-fos expression were observed on the stimulated muscle side in the cervical C2-C4 (layers 1, 3-5, 7 and 10) spinal segments, bilaterally in the lumbar L4-L6 (layer 1) segments and in contralateral central (Ce), medial (Me), and basomedial (BM) amygdaloid nuclei. A scarce number of staining cells were found within lateral and basolateral nuclei. The rostro-caudal extent of c-fos expression in the spinal cord supports functional coupling of the cervical and lumbar regions during the neck muscle fatigue development. The distinct c-fos expression in the Ce and Me amygdaloid nuclei suggests that they may contribute to mediating the neck muscle fatigue-related nociception, autonomic and behavioural responses.

[Investigation of c-fos expression and NADPH-diaphorase activity in the spine cord and brain in the development of the neck muscle weakness in rats]

The distribution of c-fos expression as a marker of neuronal activation and NADPH-diaphorase reactivity were examined in the cervical spinal cord, limbic structures and hypothalamus in anaesthetized rats after fatigue induced by intermittent high-rate (100 s(-1)) electrical stimulation of the dorsal neck muscles (mm. trapezius and splenius). In comparison to the control or sham-stimulated animals fatiguing stimulation induced significant increase in ipsilaterally in the C -C4 spinal segments and the contralateral central (Ce), medial (Me) nuclei, paraventricular nucleus of hypothalamus (Pa) and ventrolateral periaqueductal gray (VLPAG). In spinal cord the highest mean number of Fos-immunoreactive (Fos-ir) neurons per section was found in layers 1,4 and 5 (5.8 +/- 0.9, 13.1 +/- 0.9 and 11.1 +/- 0.7, P < 0.05) of the dorsal horn. The order of intensity of c-fos expression in different regions of the brain was as following sequence: Pa > VLPAG > Ce (447.7 +/- 23.5, 196.3 +/- 12.7, 104.6 +/- 12.3, respectively). About 50 % of double-labeled (Fos-ir and NADPH-diaphorase reactive) cells were found in Pa nucleus. Received data show that limbic structures, hypothalamus and VLPAG are involved in activation after neck muscle fatigue and might contribute to nociceptive processing and generation of the autonomic and affective components of the muscle pain.

[The organization of instrumental food-procuring movements in rats]

The roles of the lateral hypothalamus, basolateral nucleus of the amygdalar complex, the second field of the frontal cortex, and ventromedial thalamic nucleus in organization of the fast ballistic food-procuring movements were studied in albino rats. Sequences of uni- and bilateral destruction of the brain structures were assessed by photorecording. Movement-related neuronal activity in these structures was recorded in freely moving animals. A specific involvement of each of the above listed structures in organization of food-procuring movements was shown. The lateral hypothalamus seems to participate in initiation of the motor program and its efficient realization, the basolateral amygdala appears to produce activatory, training, and stabilizing effects. The second field of the motor cortex leads in movement acquisition (i.e., in memorizing) and decision making about triggering the program. The idea about the relay role of the thalamic motor nucleus is supplemented by understanding of its more complex integrative function.

[The role of the basolateral nuclei of the rat amygdala in organizing rapid food-acquisition movements]

The influence of electrolytic destruction of the basolateral nucleus of amygdala (BLA) on rapid food-getting movements was studied in albino rats. After one side destruction of the BLA, contralateral to the working forelimb it was found that the number of movements and their frequency decreased with an increase of their duration. After two side destruction of the BLA the number of movements increased with a decrease of their frequency. Duration of movements was unstable. After the BLA destruction (especially two side) all parameters were unstable both each day and during each experiment. Different level and character of the compensation after one- and two side destruction of the BLA was observed. The conclusion is made about the activating, stabilizing and training influences of the BLA on the rapid food-getting movements in rats.

[Role of the ventromedial nucleus of the rats thalamus in food-procuring movements]

The characteristics of ballistic food-procuring movements were studied in albino rats. After electrolytic destruction of ventromedial nucleus of thalamus (VM) of contralaterally preferred extremity the number of attempts and frequency of movements were determined to increase with a decrease of their duration. The restoration of parametres of movements took place during a week. A phase structure of movements also undergoes some modifications: in the case of invariance of initial ballistic components, conditioned by strict links of programme one-side switching off of VM tells on the following components, subject to correction. Re-teaching, requiring the modification of motor programme caused considerable difficulties in rats with switched off VM. The obtained results illustrate the significance of rats' VM in the formation and realization of motor programmes.

[Laterality of food handling movements in rats]

Lateralization of motor food skills has been investigated on 77 adult white rats. The predominance for the left anterior extremity while carrying out food was found in 53.5% of rats, the right extremity--in 36.4% of rats. 10.3% of rats belonged to ambidexters. Prevalence of using left extremity was peculiar to the females as against the male ones. Three generations of left-handed rats obtained by crossing have been followed. Rats making use of the left extremity to take out food predominated in the second and third generates.