Motor skill recovery in rats with various forelimb preference subjected to lesions in the caudate nucleus

Rats were trained for retrieving a sunflower seed from a tube using a forelimb. In the process of training, all the animals were divided in two groups: with the right- and left-limb preference. The period of learning was divided in two emotional (after the period of anxiety the animal takes a sunflower seed from the flow of a chamber) and three motor stages (different degrees of dexterity and precision in reaching a seed in the tube and grasping it). After a rat learned the skilled movement, the caudate nucleus was lesioned contralaterally to the preferred limb. After surgery, the animals were tested for recovery of the motor skill. The stages of recovery were the same as during learning. "Right-" and "left-handed" rats were compared in the percentage of animals performing each stage, duration of each stage, the depth of the tube reached by the animal's forelimb, and time required for obtaining the best results. The "right-handed" rats dominated in the percentage of animals performing the emotional stages and later began to recover the skilled movement (the crucial motor stage) but faster acquired their individual maximal depth of reaching a seed in the tube than the "left-handed" animals. The recovery of the skilled movement in the "left-handed" animals was a more gradual process than that in the "right-handed" ones.     

Various resistance of motor preference in rats exposed to forced retraining

Adult Wistar rats were trained to get food from a narrow tube under conditions of free choice of a limb. After reaching a stable level of using the preferred limb, rats (n = 35) were forced to relearn the acquired skill for reaching food with a unpreferred paw. When afterwards the rats returned to the initial conditions of free choice of a limb, 12 animals (34%) did not recover their initial preference, 8 rats (23%) were ambidextrous, and 15 animals (43%) returned to the originally preferred paw. The results demonstrated different resistance of the initial limb preference to forced retraining in different animals. It is suggested that the process of retraining per se is not the only and sufficient condition of the change in "handedness". It also suggested that the different resistance of initial preference to forced retraining reflects individual differences in a degree (intensity) of this preference, which are predetermined by internal, probably by genetic factors.     

Formation of lateralized motor skills in rats

Adult Wistar rats were trained to get food with a forepaw from a narrow tube under conditions of free choice of a limb. It was shown that the presence or absence of limb preference determined by preliminary short-run testing far from always defines the character and extent of lateralization formed in the process of training. It was also found that reaching the maximal extent of lateralization requires, on average, more extended period of training for the animals, which finally constituted the group of right-handers, than for the rats finally classified as left-handers.     

The assessment of preschool children's motor skills after familiarization with motor tests

This research study was conducted to establish the influence of familiarization on the information component of movement in a motor task for the assessment of preschool children's motor skills. The sample included 50 children whose mean age was 5.9 years (71.5 months). The experimental group consisted of 27 children who were 5.9 years (71.5 months) old, and the control group consisted of 23 children who were 5.9 years (71.5 months) old. The examinees performed 2 motor tasks, standing long jump (SJ, explosive strength) and standing on 1 leg on a beam "flamingo test" (FT, balance). The experimental group underwent a period of familiarization with the motor task in 3 sessions with 5 trials every 3 days. The results indicate statistically significant differences in the final testing between both groups of examinees; the experimental group mean was 112.73 cm, and the control group mean was 100.62 in the SJ test (p = 0.00), and the experimental group mean was 27.10 seconds and the control group mean was 15.01 seconds in the FT (for balance) (p = 0.00). The results obtained in this research indicate that children significantly improved the results in the motor test of strength and balance, being influenced by familiarization. It was confirmed that it was necessary for preschool children to be familiar with the test and it is not justified to use testing and assessment protocols and standards for adults. Physical educators and coaches, when testing preschool children, should introduce children to tests to obtain the best result.     

Androgens exacerbate motor asymmetry in male rats with unilateral 6-hydroxydopamine lesion

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopamine neuron loss in the nigrostriatal pathway that shows greater incidence in men than women. The mechanisms underlying this gender bias remain elusive, although one possibility is that androgens may increase dopamine neuronal vulnerability to oxidative stress. Motor impairment can be modeled in rats receiving a unilateral injection of 6-hydroxydopamine (6-OHDA), a neurotoxin producing nigrostriatal degeneration. To investigate the role of androgens in PD, we compared young (2 months) and aged (24 months) male rats receiving gonadectomy (GDX) and their corresponding intact controls. One month after GDX, rats were unilaterally injected with 6-OHDA, and their motor impairment and asymmetry were assessed 2 weeks later using the cylinder test and the amphetamine-induced rotation test. Plasma samples were also collected to assess the concentration of testosterone and advanced oxidation protein products, a product of oxidative stress. GDX decreased lesion-induced asymmetry along with oxidative stress and increased amphetamine-induced rotations. These results show that GDX improves motor behaviors by decreasing motor asymmetry in 6-OHDA-treated rats, an effect that may be ascribed to increased release of striatal dopamine and decreased oxidative stress. Collectively, the data support the hypothesis that androgens may underlie the gender bias observed in PD.     

Recovery of song preferences after excitotoxic HVC lesion in female canaries

The courtship solicitation display (CSD) of the female canary is a model to study estrogen dependent auditory preferences for male songs. The forebrain auditory-vocal nucleus, HVC, is part of the circuit that determines such preferences. To further develop this model we show that bilateral excitotoxic lesions of the medial part of HVC involving between 18-60% of the bilateral nucleus are behaviorally effective while complete unilateral lesions are not. Further, we show that animals recover their song preferences over a period of several months after the lesion. This functional recovery does not involve anatomical recovery of the HVC. Even 9 months after the lesion, the HVC size of these females was similar to that of females sacrificed 2 days after the lesion and thus was 40 +/- 8% smaller compared to normal females. Further, ipsilaterally, the lesion procedure transiently disturbed the neurochemistry, such as GAD-mRNA expression, in the part of HVC that did not undergo cell death. These results suggest that the integrity of the lateral part of at least one HVC is required to perform CSD in response to relevant auditory stimuli.     

Effect of neurotensin injections into caudate nuclei on realization and extinction of conditioned motor reflex in rats

It was shown that neurotensin microinjections into the caudate nuclei facilitated of a conditioned reflex but not affected its realization. Besides, neurotensin was shown to have a positive aftereffect on extinction. Motor activity of rats in the "open field" was augmented after neurotensin administration. A conclusion was drawn that the functional effect of neurotensin administration into the caudate nuclei is connected with the normalization of the motivational and emotional state of an animal rather than with the regulation of the motor function.     

Phenylalanine in the caudate nucleus of dopamine depleted rats

Dopamine depleting lesions of the substantia nigra result in a reduction of the striatal accumulation of 2-phenylethylamine following monoamine oxidase inhibition. It is established that this effect may not be due to a change in availability of aromaticL-amino acid decarboxylase in striatum. Nevertheless, the possibility remains that striatal concentrations of phenylalanine (the precursor of 2-phenylethylamine) may be altered by dopamine-depleting lesions. The present experiments assessed the effects of dopamine depletion induced by 6-OHDA (7 days following 8 g/4 l unilateral substantia nigra injection) on striatal concentrations of phenylalanine, dopamine, 5-hydroxytryptamine and their metabolites. In addition, the effects of reserpine-induced (10 mg kg^–1, 2h, sc) amine depletion on these striatal levels were also assessed. Under equivalent conditions reserpine is reported to increase striatal accumulationof 2-phenylethylamine. 6-OHDA induced a significant unilateral depletion of dopamine, DOPAC and HVA and increased 5-HIAA but had no significant effect on phenylalanine levels. Reserpine decreased dopamine and 5-hydroxytryptamine and increased DOPAC, HVA and 5-HIAA levels, no changes in phenylalanine were observed. This pattern of results was also observed when lesioned animals or reserpine-treated animals were pretreated with (-)-deprenyl (2 mg kg^–1, 2 hr, sc), the treatment previously used to induce accumulation of 2-phenylethylamine. These data indicate that changes in 2-phenylethylamine previously observed under these conditions may not simply be secondary to a change in striatal phenylalanine concentrations.     

Recovery of motor function after partial decortication under the effects of double gravitation

The motor function recovery was studied after surgical damage of the left motor cortex in albino rats in control and under double gravitation action for 20 and 40 min a day. Distance between the 1st and 5th finger was measured. The positive influence was shown on post-lesional recovery.     

Different recovery of a skilled movement after destruction of the caudate nucleus in rats with right- or left-forelimb preference]

Recovery of the motor skill of taking a sunflower seed from a tube after the electrolytic destruction of the caudate nucleus was studied in Wistar rats with left- (n = 27) and right-forelimb (n = 22) preference. The reaching performance was divided in 5 stages. The first two stages characterize the emotional condition of an animal, the following three were immediately related with the skilled movement. After preliminary testing, the head of the caudate nucleus contralateral to the preferred limb was electrolytically damaged. After surgery, rats were tested during 20 weeks, and in every test the following indices were measured: percent of rats which perform the movement characteristic for the given stage, stage duration, depth of reaching a flower seed from the tube, time necessary to obtain the best results etc. It was found that at the "emotional" stages, higher percent of the right-handed animals perform the characteristic movements, but they spend more time to complete these stages than the left-handed rats. In rats with the left-limb dominance the recovery of the specialized movement is positively correlated with the time of the recovery onset at all the stages, while there is no such correlation in rats with right-limb dominance. Both groups of animals reach the same depth of the tube in the course of recovery, but the left-handed rats attain these results later and gradually, while the right-handed animals attain the maximal extent of recovery spontaneously and earlier than left-handed ones.     

Recovery of fine motor performance after ischemic damage to motor cortex is facilitated by cell therapy in the rhesus monkey

Abstract

We investigated the efficacy on recovery of function following controlled cortical ischemia in the monkey of the investigational cell drug product, CNTO 0007. This drug contains a cellular component, human umbilical tissue-derived cells, in a proprietary thaw and inject formulation. Results demonstrate significantly better recovery of motor function in the treatment group with no difference between groups in the volume or surface area of ischemic damage, suggesting that the cells stimulated plasticity.     

Reduction in parvalbumin expression in the zona incerta after 6OHDA lesion in rats

In an effort to understand better the neurochemical changes that occur in Parkinson disease, we have examined the expression patterns of the calcium-binding protein parvalbumin in the zona incerta in parkinsonian rats. Sprague-Dawley rats had small volumes of either saline (control) or 6 hydroxydopamine (6OHDA) injected into the medial forebrain bundle, the major tract carrying dopaminergic nigrostriatal axons. After various post-lesion survival periods, ranging from 2 hrs to 84 days, rats were perfused with formaldehyde and their brains processed for routine tyrosine hydroxylase (TH) or parvalbumin immunocytochemistry. In the 3 to 84 days post-lesion cases, there was an overall 50% reduction in the number of parvalbumin⁺ cells in the zona incerta on the 6OHDA-lesioned side when compared to control. In the 2 hrs post-lesion cases, there was no substantial loss of parvalbumin⁺ cells in the zona incerta after 6OHDA lesion, although in these cases (unlike the longer survival periods), there was limited loss of TH⁺ cells in the midbrain on the lesion side. The loss of parvalbumin⁺ cells from the zona incerta was due to a loss of antigen expression rather than a loss of the cells themselves, since the number of Nissl-stained cells in the zona incerta was similar on the control and 6OHDA-lesioned sides. In summary, our results indicate that a loss of the midbrain dopaminergic cells induces a major change in parvalbumin expression within the zona incerta. This change may have key functional and clinical implications.