Effect of skilled and unskilled training on nerve regeneration and functional recovery

The most disabling aspect of human peripheral nerve injuries, the majority of which affect the upper limbs, is the loss of skilled hand movements. Activity-induced morphological and electrophysiological remodeling of the neuromuscular junction has been shown to influence nerve repair and functional recovery. In the current study, we determined the effects of two different treatments on the functional and morphological recovery after median and ulnar nerve injury. Adult Wistar male rats weighing 280 to 330 g at the time of surgery (N = 8-10 animals/group) were submitted to nerve crush and 1 week later began a 3-week course of motor rehabilitation involving either "skilled" (reaching for small food pellets) or "unskilled" (walking on a motorized treadmill) training. During this period, functional recovery was monitored weekly using staircase and cylinder tests. Histological and morphometric nerve analyses were used to assess nerve regeneration at the end of treatment. The functional evaluation demonstrated benefits of both tasks, but found no difference between them (P > 0.05). The unskilled training, however, induced a greater degree of nerve regeneration as evidenced by histological measurement (P < 0.05). These data provide evidence that both of the forelimb training tasks used in this study can accelerate functional recovery following brachial plexus injury.

Transplantation of mononuclear cells from human umbilical cord blood promotes functional recovery after traumatic spinal cord injury in Wistar rats

Cell transplantation is a promising experimental treatment for spinal cord injury. The aim of the present study was to evaluate the efficacy of mononuclear cells from human umbilical cord blood in promoting functional recovery when transplanted after a contusion spinal cord injury. Female Wistar rats (12 weeks old) were submitted to spinal injury with a MASCIS impactor and divided into 4 groups: control, surgical control, spinal cord injury, and one cell-treated lesion group. Mononuclear cells from umbilical cord blood of human male neonates were transplanted in two experiments: a) 1 h after surgery, into the injury site at a concentration of 5 x 10⁶ cells diluted in 10 µL 0.9% NaCl (N = 8-10 per group); b) into the cisterna magna, 9 days after lesion at a concentration of 5 x 10⁶ cells diluted in 150 µL 0.9% NaCl (N = 12-14 per group). The transplanted animals were immunosuppressed with cyclosporin-A (10 mg/kg per day). The BBB scale was used to evaluate motor behavior and the injury site was analyzed with immunofluorescent markers to label human transplanted cells, oligodendrocytes, neurons, and astrocytes. Spinal cord injury rats had 25% loss of cord tissue and cell treatment did not affect lesion extension. Transplanted cells survived in the injured area for 6 weeks after the procedure and both transplanted groups showed better motor recovery than the untreated ones (P < 0.05). The transplantation of mononuclear cells from human umbilical cord blood promoted functional recovery with no evidence of cell differentiation.

Effects of physical exercise on spatial memory and astroglial alterations in the hippocampus of diabetic rats

Type 1 diabetes mellitus (T1DM) is associated with neurocognitive dysfunction and astrogliosis. Physical exercise prevents cognitive impairments and induces important brain modifications. The aim of our study was to investigate the effect of treadmill exercise on spatial memory and astrocytic function in the hippocampus of a T1DM model. Fifty-seven Wistar rats were divided into four groups: trained control (TC) (n = 15), non-trained control (NTC) (n = 13), trained diabetic (TD) (n = 14) and non-trained diabetic (NTD) (n = 15). One month after streptozotocin-induced diabetes, exercise groups were submitted to 5 weeks of physical training, and then, all groups were assessed in the novel object-placement recognition task. Locomotor activity was analyzed in the open field apparatus using Any-maze software. The expression of glial fibrillary acidic protein (GFAP) and S100B in hippocampus and cerebrospinal fluid were measured using ELISA assay, and hippocampal GFAP immunoreactivity was evaluated by means of immunohistochemistry and optical densitometry. The results showed that physical exercise prevents and/or reverts spatial memory impairments observed in NTD animals (P < 0.01). Decreased locomotor activity was observed in both the NTD and TD groups when compared with controls (P < 0.05). ELISA and immunohistochemistry analyzes showed there was a reduction in GFAP levels in the hippocampus of NTD animals, which was not found in TD group. ELISA also showed an increase in S100B levels in the cerebrospinal fluid from the NTD group (P < 0.01) and no such increase was found in the TD group. Our findings indicate that physical exercise prevents and/or reverts the cognitive deficits and astroglial alterations induced by T1DM.

Olfactory and respiratory lamina propria transplantation after spinal cord transection in rats: effects on functional recovery and axonal regeneration

Spinal cord injury (SCI) has very poor clinical prospects, resulting in irreversible loss of function below the injury site. Although applied in clinical trials, olfactory ensheathing cells transplantation (OEC) derived from lamina propria (OLP) is still a controversial repair strategy. The present study explored the efficacy of OLP or respiratory lamina propria (RLP) transplantation and the optimum period after SCI for application of this potential therapy. Adult male rats were submitted to spinal cord transection and underwent acute, 2-week or 4-week post-injury transplantation with pieces of OLP (containing OECs) or RLP (without OECs). After grafting, animals with OLP and RLP showed discrete and similar hindlimb motor improvement, with comparable spinal cord tissue sparing and sprouting in the lesion area. Acute transplantation of OLP and RLP seems to foster limited supraspinal axonal regeneration as shown by the presence of neurons stained by retrograde tracing in the brainstem nuclei. A larger number of 5-HT positive fibers were found in the cranial stump of the OLP and RLP groups compared to the lesion and caudal regions. Calcitonin gene-related peptide fibers were present in considerable numbers at the SCI site in both types of transplantation. Our results failed to verify differences between acute, 2-week and 4-week delayed transplantation of OLP and RLP, suggesting that the limited functional and axon reparative effects observed could not be exclusively related to OECs. A greater understanding of the effects of these tissue grafts is necessary to strengthen the rationale for application of this treatment in humans.

Treadmill training induces plasticity in spinal motoneurons and sciatic nerve after sensorimotor restriction during early postnatal period: new insights into the clinical approach for children with cerebral palsy

The aim of the present study was to investigate whether locomotor stimulation training could have beneficial effects on the morphometric alterations of spinal cord and sciatic nerve consequent to sensorimotor restriction (SR). Male Wistar rats were exposed to SR from postnatal day 2 (P2) to P28. Control and experimental rats underwent locomotor stimulation training in a treadmill for three weeks (from P31 to P52). The cross-sectional area (CSA) of spinal motoneurons innervating hind limb muscles was determined. Both fiber and axonal CSA of myelinated fibers were also assessed. The growth-related increase in CSA of motoneurons in the SR group was less than controls. After SR, the mean motoneuron soma size was reduced with an increase in the proportion of motoneurons with a soma size of between 0 and 800 μm(2). The changes in soma size of motoneurons were accompanied by a reduction in the mean fiber and axon CSA of sciatic nerve. The soma size of motoneurons was reestablished at the end of the training period reaching controls level. Our results suggest that SR during early postnatal life retards the growth-related increase in the cell body size of motoneurons in spinal cord and the development of sciatic nerve. Additionally, three weeks of locomotor stimulation using a treadmill seems to have a beneficial effect on motoneurons' soma size.

The effects of treadmill training on young and mature rats after traumatic peripheral nerve lesion

The purpose of this study was to investigate the possible effects of a treadmill training program on regeneration in young (3-month-old) and mature (13-month-old) rats with sciatic nerve crush using functional, electrophysiological, and morphometric analyses. When compared to both the young and mature untrained injury groups, those groups that underwent a treadmill training showed improved sensorimotor function evaluated by narrow beam test (p<0.04 and p<0.001, respectively), while muscle action potential amplitude was only greater in the young group (p<0.02). The treadmill training program was able to reduce myelinated fiber density in the young group (p<0.001), which appeared to increase after nerve injury (poly-innervation), but decreased with training, which means that the innervation became more functional. The data indicate that treadmill training is able to promote functional, electrophysiological and morphological recovery in young animals. However, in mature animals, improvement was only seen in terms of functional recovery.

Balance and coordination training after sciatic nerve injury

INTRODUCTION

Numerous therapeutic interventions have been tested to enhance functional recovery after peripheral nerve injuries.

METHODS

After sciatic nerve crush in rats we tested balance and coordination and motor control training in sensorimotor tests and analyzed nerve and muscle histology.

RESULTS

The balance and coordination training group and the sham group had better results than the sedentary and motor control groups in sensorimotor tests. The sham and balance and coordination groups had a significantly larger muscle area than the other groups, and the balance and coordination group showed significantly better values than the sedentary and motor control groups for average myelin sheath thickness and g-ratio of the distal portion of the nerve.

CONCLUSIONS

The findings indicate that balance and coordination training improves sciatic nerve regeneration, suggesting that it is possible to revert and/or prevent soleus muscle atrophy and improve performance on sensorimotor tests.

Treadmill step training-induced adaptive muscular plasticity in a chronic paraplegia model

The purpose of this study was to provide evidence that treadmill step training is capable of attenuating muscle atrophy and may regulate brain derived neurotrophic factor (BDNF) in soleus muscle after complete spinal cord transection (SCT) at T8-T9 in rats. Five days after SCT, spinal animals started a 9-week step-training program on a treadmill with partial body weight support and manual step help. The muscular trophism was studied by analyzing muscle weight and myofiber cross-sectional area of the soleus, while Western blot analysis was used to detect BDNF expression in the same muscle. Step training, initiated immediately after SCT in rats, may partially impede/revert muscular atrophy in chronic paralyzed soleus muscle. Moreover, treadmill step training promoted upregulation of the BDNF in soleus muscle, which was positively correlated with muscle weight and myofiber cross-sectional size. These findings have important implications for the comprehension of the neurobiological substrate that promotes exercise-induced effects on paralyzed skeletal muscle and suggests treadmill training is a viable therapeutic approach in spinal cord injuries.

The Amazonian herbal Marapuama attenuates cognitive impairment and neuroglial degeneration in a mouse Alzheimer model

Alzheimer's disease (AD) is expected to affect more than 22 million people worldwide by 2025, causing devastating suffering and enormous costs to families and society. AD is a multifactorial disease, with a complex pathological mosaic. In rodents, AD-like dementia can be induced by cerebral microinjection of Aβ peptide, leading to amyloid deposits, amnesia and various features of neurodegeneration. Marapuama (Ptychopetalum olacoides) is regarded as a "brain tonic" in the Amazon region and shows a nootropic profile in rodents.

AIM OF THE STUDY

Because a specific extract (POEE) of Marapuama was shown to possess promnesic and anti-amnesic properties, the aim of this study was to verify if POEE is also effective against Aβ(1-42)-induced cognitive deficit in mice. Additionally, Aβ deposits (Congo red), GFAP immunoreactivity (immunohistochemistry), and neurodegenerative changes in the hippocampal pyramidal layer (Nissl) were examined as measures of Aβ(1-42)-induced neurodegeneration.

MATERIALS AND METHODS

CF1 mice were subjected to the experimental Alzheimer model with the Aβ(1-42) i.c.v. administration. The effects of POEE 800 mg/kg were evaluated over 14 consecutive days of treatment.

RESULTS

The data show that 14 days of oral treatment with POEE (800 mg/kg) was effective in preventing Aβ-induced cognitive impairment, without altering the levels of BDNF and with parallel reductions in Aβ deposits and astrogliosis. CA1 hippocampus loss induced by Aβ(1-42) was also diminished in POEE-treated mice.

CONCLUSION

This study offers evidence of functional and neuroprotective effects of two weeks treatment with a Ptychopetalum olacoides extract against Aβ peptide-induced neurotoxicity in mice. Given the multifactorial nature of neurodegeneration, the considerable potential for an AChE inhibitor displaying associated neuroprotective properties such as here reported warrants further clinic evaluation.

Treadmill training improves motor skills and increases tyrosine hydroxylase immunoreactivity in the substantia nigra pars compacta in diabetic rats

The aim of this study was to evaluate the effects of treadmill training on motor skills and immunoreactivity to tyrosine hydroxylase in the substantia nigra pars compacta and ventral tegmental area from diabetic rats induced by streptozotocin. Male Wistar rats were divided into three groups: control, diabetic and trained diabetic. Treadmill training was performed for 8weeks. Blood glucose concentrations and body weight were evaluated 48h after diabetes induction and every 30days thereafter. Motor skills were evaluated on the rotarod and open field tests. Then, animals were transcardially perfused and the brains were post-fixed, cryoprotected and sectioned in a cryostat. Immunohistochemistry for tyrosine hydroxylase analyses was done in the ventral tegmental area and in the substantia nigra. Motor skills showed that diabetic animals had a decrease in the latency to fall and enhanced number of falls in the rotarod test compared to control and trained diabetic animals. In the open field, diabetic animals had a decrease in the number of crossed squares, rearings and spent a less time moving compared to control and trained diabetic animals. In diabetic animals, optical densitometry of immunohistochemistry showed that tyrosine hydroxylase reaction decreased in the ventral tegmental area and in the neurons and process in the substantia nigra. In the later region, that decrease was reversed by treadmill training. In conclusion, we demonstrated that treadmill training can reverse the loss of the motor skills, which was correlated to tyrosine hydroxylase immunoreactivity in the substantia nigra of diabetic animals without pharmacological treatment.

Thermographic evaluation of hind paw skin temperature and functional recovery of locomotion after sciatic nerve crush in rats

INTRODUCTION

Peripheral nerves are often damaged by direct mechanical injury, diseases, and tumors. The peripheral nerve injuries that result from these conditions can lead to a partial or complete loss of motor, sensory, and autonomic functions, which in turn are related to changes in skin temperature, in the involved segments of the body. The aim of this study was to evaluate the changes in hind paw skin temperature after sciatic nerve crush in rats in an attempt to determine whether changes in skin temperature correlate with the functional recovery of locomotion.

METHODS

Wistar rats were divided into three groups: control (n = 7), sham (n = 25), and crush (n = 25). All groups were subjected to thermographic, functional, and histological assessments.

RESULTS

ΔT in the crush group was different from the control and sham groups at the 1st, 3rd and 7rd postoperative days (p<0.05). The functional recovery from the crush group returned to normal values between the 3rd and 4th week post-injury, and morphological analysis of the nerve revealed incomplete regeneration at the 4th week after injury.

DISCUSSION

This study is the first demonstration that sciatic nerve crush in rats induces an increase in hind paw skin temperature and that skin temperature changes do not correlate closely with functional recovery.

Acetylcholinesterase inhibition in cognition-relevant brain areas of mice treated with a nootropic Amazonian herbal (Marapuama)

The goal of acetylcholinesterase inhibitors (AChEIs) used to treat Alzheimer's patients is an improvement in cholinergic transmission. While currently available AChEIs have limited success, a huge impediment to the development of newer ones is access to the relevant brain areas. Promnesic, anti-amnesic and AChEI properties were identified in a standardized ethanol extract from Ptychopetalum olacoides (POEE), a medicinal plant favored by the elderly in Amazon communities. The purpose of this study was to provide conclusive evidence that orally given POEE induces AChE inhibition in brain areas relevant to cognition. Histochemistry experiments confirmed that the anticholinesterase compound(s) present in POEE are orally bioavailable, inducing meaningful AChE inhibition in the hippocampus CA1 (∼33%) and CA3 (∼20%), and striatum (∼17%). Ellman's colorimetric analysis revealed that G1 and G4 AChE isoforms activities were markedly inhibited (66 and 72%, respectively) in hippocampus and frontal cortex (50 and 63%, respectively), while G4 appeared to be selectively inhibited (72%) in the striatum. Western blotting showed that POEE did not induce significant changes in the AChE immunocontent suggesting that its synthesis is not extensively modified. This study provides definitive proof of meaningful anticholinesterase activity compatible with the observed promnesic and anti-amnesic effects of POEE in mice, reaffirming the potential of this extract for treating neurodegenerative conditions where a hypofunctioning cholinergic neurotransmission is prominent. Adequate assessment of the safety and efficacy of this extract and/or its isolated active compound(s) are warranted.

Distribution of NADPH-diaphorase activity in the central nervous system of the young and adult land snail Megalobulimus abbreviatus

Nitric oxide (NO) is a gas produced through the action of nitric oxide synthase that acts as a neurotransmitter in the central nervous system (CNS) of adult gastropod mollusks. There are no known reports of the presence of NOS-containing neurons and glial cells in young and adult Megalobulimus abbreviatus. Therefore, NADPH-d histochemistry was employed to map the nitrergic distribution in the CNS of young and adult snails in an attempt to identify any transient enzymatic activity in the developing CNS. Reaction was observed in neurons and fibers in all CNS ganglia of both age groups, but in the pedal and cerebral ganglia, positive neurons were more intense than in other ganglia, forming clusters symmetrically located in both paired ganglia. However, neuronal NADPH-d activity in the mesocerebrum and pleural ganglia decreased from young to adult animals. In both age groups, positive glial cells were located beneath the ganglionic capsule, forming a network and surrounding the neuronal somata. The trophospongium of large and giant neurons was only visualized in young animals. Our results indicate the presence of a nitrergic signaling system in young and adult M. abbreviatus, and the probable involvement of glial cells in NO production.

Treadmill training increases the size of A cells from the L5 dorsal root ganglia in diabetic rats

The aim of this study was to evaluate the effects of physical training on the L5 dorsal root ganglion (DRG) cells in streptozotocin diabetic rats. Male adult rats were divided into 3 groups: (control, diabetic and trained diabetic). Treadmill training was performed for 10 weeks (5 days/week, twice a day). Blood glucose concentrations and body weight were evaluated 48h after diabetes induction and every 30 days thereafter. Then, animals were killed and the right L5 DRG removed. Histological and morphometric analysis consisted of evaluating nuclear and cellular volumes and areas in A and B cells at light and ultrastructural levels. Blood glucose concentrations were higher in both diabetic groups vs controls at all periods. Body weights were lower in all diabetics vs controls at all periods after diabetes induction, with a significant time vs group interaction. In A cells, the cellular and nuclear volumes were lower than control animals only in the diabetic group; control and trained diabetic animals did not differ; in B cells the cellular and nuclear volumes were lower in diabetic and trained diabetic rats. The cellular areas of A cells were smaller in diabetic rats than in control and trained diabetic rats, while the cellular areas of B cells were smaller in the diabetic and trained groups. In conclusion, treadmill training was able to increase the size of A cells from the DRG in diabetic rats and improved the morphological features of these cells.

Ultrastructural analysis of the dorsal body gland of the terrestrial snail Megalobulimus abbreviatus (Becquaert, 1948)

The ultrastructure of the reproductive gland, dorsal body (DB), of Megalobulimus abbreviatus was analysed. Electron microscope immunohistochemistry was used to detect FMRFamide-like peptides in the nerve endings within this gland. Nerve backfilling was used in an attempt to identify the neurons involved in this innervation. In M. abbreviatus, the DB has a uniform appearance throughout their supraesophageal and subesophageal portions. Dorsal body cells have several features in common with steroid-secreting gland cells, such as the presence of many lipid droplets, numerous mitochondria with tubular cristae and a developed smooth endoplasmic reticulum cisternae. Throughout the DB in M. abbreviatus numerous axonal endings were seen to be in contact with the DB cells exhibiting a synaptic-like structure. The axon terminals contained numerous electron-dense and scanty electron-lucid vesicles. In addition, the DB nerve endings exhibited FMRFamide immunoreactive vesicles. Injection of neural tracer into the DB yielded retrograde labelling of neurons in the metacerebrum lobe of the cerebral ganglia and in the parietal ganglia of the subesophageal ganglia complex. The possibility that some of these retrograde-labelled neurons might be FMRFamide-like neurons that may represent a neural control to the DB in M. abbreviatus is discussed.

Different effects of anoxia and hind-limb immobilization on sensorimotor development and cell numbers in the somatosensory cortex in rats

Cerebral palsy (CP) is a group of movement and posture disorders attributed to insults in the developing brain. In rats, CP-like motor deficits can be induced by early hind-limb sensorimotor restriction (SR; from postnatal days P2 to P28), associated or otherwise with perinatal anoxia (PA; on P0 and P1). In this study, we address the question of whether PA, early SR or a combination of both produces alterations to sensorimotor development. Developmental milestones (surface righting, cliff aversion, stability on an inclined surface, proprioceptive placing, auditory startle, eye opening) were assessed daily from P3 to P14. Motor skills (horizontal ladder and beam walking) were evaluated weekly (from P31 to P52). In addition, on P52, the thickness of the somatosensory (S1) and cerebellar cortices, and corpus callosum were measured, and the neuronal and glial cell numbers in S1 were counted. SR (with or without PA) significantly delayed the stability on an inclined surface and hastened the appearance of the placing reflex and impaired motor skills. No significant differences were found in the thickness measurements between the groups. Quantitative histology of S1 showed that PA, either alone or associated with SR, increased the number of glial cells, while SR alone reduced neuronal cell numbers. Finally, the combination of PA and SR increased the size of neuronal somata. We conclude that SR impairs the achievement of developmental milestones and motor skills. Moreover, both SR and PA induce histological alterations in the S1 cortex, which may contribute to sensorimotor deficits.

Beneficial effects of treadmill training in experimental diabetic nerve regeneration

OBJECTIVES

We investigated the effects of treadmill training (10 weeks) on hindlimb motor function and nerve morphometric parameters in diabetic rats submitted to sciatic nerve crush.

MATERIALS AND METHOD

Wistar rats (n = 64) were divided into the following groups: non-diabetic; trained non-diabetic; non-diabetic with sciatic nerve crush; trained non-diabetic with sciatic nerve crush; diabetic; trained diabetic; diabetic with sciatic nerve crush or trained diabetic with sciatic nerve crush. Diabetes was induced by streptozotocin injection (50 mg/kg, iv). Hindlimb motor function was evaluated weekly by assessing sciatic functional indices, and the proximal and distal portions of the sciatic nerve were used for morphometric analysis.

RESULTS

At 13 weeks post-injury, the distal nerve portion of all injured groups and the proximal nerve portion of the diabetic with sciatic nerve crush group presented altered morphometric parameters such as decreased myelinated fiber diameter (~7.4 + 0.3μm vs ~4.8 + 0.2μm), axonal diameter (~5 + 0.2μm vs ~3.5 + 0.1μm) and myelin sheath thickness (~1.2 + 0.07μm vs ~0.65 + 0.07μm) and an increase in the percentage of area occupied by endoneurium (~28 + 3% vs ~60 + 3%). In addition, in the non-diabetic with sciatic nerve crush group the proximal nerve portion showed a decreased myelinated fiber diameter (7.4+0.3μm vs 5.8 + 0.3μm) and myelin sheath thickness (1.29 + 0.08μm vs 0.92 + 0.08μm). The non-diabetic with sciatic nerve crush, trained non-diabetic with sciatic nerve crush, diabetic with sciatic nerve crush and trained diabetic with sciatic nerve crush groups showed normal sciatic functional index from the 4th,4th,9th and 7th week post-injury, respectively. Morphometric alterations in the proximal nerve portion of the diabetic with sciatic nerve crush and non-diabetic with sciatic nerve crush groups were either prevented or reverted to values similar to the non-diabetic group by treadmill training.

CONCLUSION

Diabetic condition promoted delay in sciatic nerve regeneration. Treadmill training is able to accelerate hindlimb motor function recovery in diabetic injured rats and prevent or revert morphometric alterations in proximal nerve portions in non-diabetic and diabetic injured rats.