Activity of neurons of the cerebral A5 zone of rat induced by adequate stimulation of muscle afferents: On the control of arterial pressure and respiration during muscle activity

Integrative function of proprioceptive system in the acute effects of whole body vibration on the movement performance in young adults

Background

The proprioceptive system coordinates locomotion, but its role in short-term integration and recovery of motor activity in imbalance of motor patterns and body remains debated. The aim of this study is investigating the functional role of proprioceptive system in motor patterns and body balance in healthy young adults.

Methods

70 participants (aged 20.1 ± 0.3) were divided into experimental groups EG1 (n = 30), EG2 (n = 30), control group (CG, n = 10). EG1 performed single WBV session on Power Plate (7 exercises adapted to Functional Movement Screen (FMS). EG2 performed single session of FMS Exercises (FMSE). CG didn't perform any physical activity. All participants performed pre- and post-session of FMS and stabilometric measurements.

Results

FMS total score in EG1 increased by 2.0 ± 0.2 (p0 < 0.001), this was significantly differed (p0 < 0.001) from EG2 and CG. Acute effects of WBV and FMSE on rate of change and standard deviation (SD) of pressure center (COP) were shown in all groups during Static Test (p0 < 0.01). SD increased (p0 < 0.01) in Given Setting Test in EG1 and EG2, and in Romberg Test (p0 < 0.001) in EG1. Length, width and area (p0 < 0.01) of confidence ellipse, containing 95% of the statokinesiogram points, decreased in Static Test in EG1; width and area (p0 < 0.01) decreased in EG2 group. Significant (p0 < 0.01) decrease in Given Setting Test was in EG1, and significant (p0 < 0.01) increase was in Romberg Test (open eyes) in CG. Maximum amplitude of COP oscillations: significantly (p0 < 0.01) decreasing along X and Y axes in EG1 and EG2, and along Y axis in CG during Static Test; along Y axis (p0 < 0.01) in all groups during Given Setting Test. Significant differences were identified (p0 < 0.01) in calculated energy consumption for COP moving during all stabilometric tests. However, inter-group differences in COP after acute WBV and FMSE sessions have not been identified.

Conclusions

Acute WBV session eliminates the deficits in motor patterns which is not the case after acute FMSE session, which, according to our integrative movement tuning hypothesis, is due to high activation of integrative function of proprioceptive system. Efficacy of WBV and FMSE on COP performance indicates a high sensitivity of postural control to different levels of proprioceptive system activity.

NMDA Receptors of A5 Area in the Regulation of Blood Pressure and Respiratory Activity during Hypoxia in Rats

In narcotized (40 mg/kg sodium ethaminal intraperitoneally) spontaneously breathing albino rats, experimental short-term hypoxia induced BP drop and increased phrenic nerve firing rate. Unilateral microinjection of a selective NMDA receptor blocker ketamine hydrochloride (50 nl; 4 mM) into A5 area did not affect BP and phrenic nerve fi ring rate. However, against the background of preliminary NMDA receptor blockage, hypoxia more markedly stimulated rhythmic activity of the respiratory center and hypotensive response. Unilateral microinjection of a selective blocker of non-NMDA receptors GAMS (50 nl; 4 mM) into A5 area did not change initial BP and phrenic nerve fi ring rate. The studied parameters in rats exposed to hypoxia after blockage of non-NMDA receptors in A5 area did not differ from the control levels. Thus, activity of the respiratory center and BP in rats during hypoxia is regulated by the structures in A5 area and NMDA glutamate receptors.