Electrophysiological study of effects of chronic injection of caffeine on defensive reflex conditioning in grape snail

It was found that chronic injection of caffeine to grape snail increases a velocity of elaboration of conditioned defensive reflex. It was shown that after daily injection of caffeine immediately after procedure of learning the conditioned defensive reflex elaborated faster than daily injection before procedure of learning. It has been shown, that chronic injection of caffeine both in naive as well as learned snails led to depolarizing shift of membrane potential and to decrease of threshold potential of command neurons of the defensive behaviour of grape snails. It was also found that addition of caffeine in bath solution led to decrease of threshold of generation of action potential of command neurons both in intact and learned snails. The resting membrane potential of command neurons was not changed.     

Comparative investigation of influence of injections of chlorpromazine and 5,6-dihydroxytryptamine on locomotion, defensive reactions of snall helix lucorum and excitability of command neurons in long-term sensitization

Comparative analysis of the action of chlorpromazine (CPZ) and neurotoxin 5,6-dihydroxytryptamine (5,6-DHT) on defensive reactions and locomotion of grape snail and elaboration of long-term sensitization (LTS), was carried out. Long-term (chronic) injection of chlorpromazine led to significant increasing of a pneumostome closing time and to changing of motor behaviour towards decrease of the velocity of the locomotion. Daily injections of 5,6-DHT in small doses within a week were accompanied by the gradual decrease of the velocity of snails locomotion, which was kept for a week. Similar effect was observed in injection of neurotoxin (30 mgs/kg). Injections of CPZ prevents elaboration of LTS, as well as injections of 5,6-DHT. After the action of CPZ, LTS, LTS followed by CPZ, and also during elaboration of LTS after injection of CPZ, the velocity of locomotion directly depended on the length of leg. During elaboration of LTS after injection of 5,6-DHT, such dependency is not retained. Electrophysiological study revealed that chronic injections of CPZ led to depolarizing shift of membrane potential and decrease of the threshold of action potential generation in command neurons as after injection of neurotoxin 5,6-DHT. Therefore, the action of neuroleptic drug CPZ on the defensive behaviour, locomotion of grape snail and electrical characteristics of identifying neurons is comparable with the action of toxic analogue of serotonin.     

The physiological basis of transplantation of fetal catecholaminergic neurons in the transected spinal cord of the rat

1. Fetal (E.17) rat locus coeruleus and mesencephalic dopaminergic neurons when implanted into the transected spinal cord of the young adult rat survive for periods of longer than four months. Axons of up to 15 mm in length are observed growing from the cell bodies of the implanted neurons. 2. Fluorescent catecholaminergic (presumably dopaminergic) cell bodies are found in the caudal region of the transected, non-implanted spinal cord. 3. After transection of the spinal cord at the middle thoracic region in rats, at different postnatal ages (PN. 0, 7, 14, 21 and 28), there is substantial recovery of motor coordination involving all four limbs in the PN. 0 and PN. 7 groups. Recovery is best in the PN. 7 group. There is almost no recovery in the PN. 28 group, and very little recovery in the PN. 14 and PN. 21 groups. 4. Spinal locomotor generators in rat can, therefore, display a substantial degree of functional autonomy, if the spinal cord is cut before a certain critical stage of development (before PN. 14). These results have interesting implications with regard to current efforts to understand the mechanisms that regulate the spinal locomotor generators in experimental animals, and perhaps in man as well.     

Haloperidol-loaded polysorbate-coated polymeric nanocapsules decrease its adverse motor side effects and oxidative stress markers in rats

Haloperidol is the most widely used antipsychotic drug in the treatment of psychiatric disorders. Despite its satisfactory therapeutic effect, its chronic use is related to severe motor side effects. Here, we investigate the incidence of motor side effects of haloperidol-loaded nanocapsules when compared to free haloperidol and the relation with oxidative stress (OS) development. Both vehicle (B-NcFO) and haloperidol loaded polysorbate-coated nanocapsules suspension (H-NcFO) prepared with fish oil as core showed uniform and rounded particles, nanometric size, negative zeta potential, low polydispersity indices and high encapsulation efficiency. Wistar rats received a single dose of free haloperidol (FH), B-NcFO or H-NcFO (0.2mg/kg ip) and were submitted to acute motor side effects evaluation 1h after the injection. Lower catalepsy time and oral dyskinesia were observed in H-NcFO-treated group than in FH group; however, both formulations decreased animals' locomotor activity. In a experiment performed subchronically, rats injected daily with H-NcFO (0.2mg/kg-ip) for 28days showed decreased oral dyskinesia frequency and catalepsy time and no impairment on locomotor activity as compared to FH group (0.2mg/kg-ip). FH group showed higher OS, as observed by increased lipid peroxidation and reduced glutathione levels and catalase activity in extrapyramidal region. Our findings showed that nanocapsules may be an efficient form to prevent or minimize haloperidol motor side effects, which are related to OS development, ameliorating psychiatric patients' quality of life.     

Combinational therapy of lithium and human neural stem cells in rat spinal cord contusion model

A large number of treatment approaches have been used for spinal cord injury improvement, a medically incurable disorder, and subsequently stem cell transplantation appears to be a promising strategy. The main objective of this study is to ascertain whether combinational therapy of human neural stem cells (hNSCs) together with lithium chloride improves cell survival, proliferation, and differentiation in a rat spinal contusion model, or not. Contusive spinal cord injury was implemented on Wistar male rats. Experimental groups comprised of: control, hNSCs transplanted, lithium chloride (Li), and hNSCs and lithium chloride (hNSCs + Li). In every experimental group, locomotor activity score and motor evoked potential (MEP) were performed to evaluate motor recovery as well as histological assessments to determine mechanisms of improvement. In accordance with our results, the hNSCs + Li and the Li groups showed significant improvement in locomotor scores and MEP. Also, Histological assessments revealed that transplanted hNSCs are capable of differentiation and migration along the spinal cord. Although NESTIN-positive cells were proliferated significantly in the Lithium group in comparison with control and the hNSCs + Li groups, the quantity of ED1 cells in the hNSCs + Li was significantly larger than the other two groups. Our results demonstrate that combinational therapy of hNSCs with lithium chloride and lithium chloride individually are adequate for ameliorating more than partial functional recovery and endogenous repair in spinal cord-injured rats.     

Functional recovery of paraplegic rats and motor axon regeneration in their spinal cords by olfactory ensheathing glia

Axonal regeneration in the lesioned mammalian central nervous system is abortive, and this causes permanent disabilities in individuals with spinal cord injuries. In adult rats, olfactory ensheathing glia (OEG) transplants successfully led to functional and structural recovery after complete spinal cord transection. From 3 to 7 months post surgery, all OEG-transplanted animals recovered locomotor functions and sensorimotor reflexes. They presented voluntary hindlimb movements, they supported their body weight, and their hindlimbs responded to light skin contact and proprioceptive stimuli. In addition, relevant motor axons (corticospinal, raphespinal, and coeruleospinal) regenerated for long distances within caudal cord stumps. Therefore, OEG transplantation provides a useful repair strategy in adult mammals with traumatic spinal cord injuries. Our results with these cells could lead to new therapies for the treatment of spinal cord lesions in humans.     

Statistical characteristics of unit activity in spinal locomotor centers

A statistical analysis of unit activity in spinal locomotor centers was undertaken on immobilized thalamic cats at rest and during generation of efferent discharges. Activation of the spinal locomotor generator was accompanied by shortening of interspike intervals in the spike sequences of neurons and a decrease in their fluctuations. Histograms of interspike intervals became more symmetrical under these circumstances and there was a considerable increase in the number of neurons whose activity showed regular fluctuations on autocorrelation histograms. Spike trains at rest were characterized by dependence of successive intervals, which increased during efferent discharge generation. The possible mechanisms of modification of the time structure of unit activity in spinal locomotor centers during their activation are discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 12, No. 2, pp. 192–198, March–April, 1980.     

Lentiviral vector delivery of short hairpin RNA to NG2 and neurotrophin-3 promotes locomotor recovery in injured rat spinal cord

Background aimsIn this study we investigated the effect of neurotrophin-3 (NT-3) and knockdown of NG2, one of the main inhibitory chondroitin sulfate proteoglycans (CSPG), in the glial scar following spinal cord injury (SCI).MethodsShort hairpin (sh) RNA were designed to target NG2 and were cloned into a lentiviral vector (LV). A LV was also constructed containing NT-3. LV expressing NT-3, shRNA to NG2 or combinations of both vectors were injected directly into contused rat spinal cords 1 week post-injury. Six weeks post-injection of LV, spinal cords were examined by histology for changes in scar size and by immunohistochemistry for changes in expression of CSPG, NT-3, astrocytes, neurons and microglia/macrophages. Motor function was assessed using the Basso, Beattie and Bresnahan (BBB) locomotor scale.ResultsAnimals that received the combination treatment of LV shNG2 and LV NT-3 showed reduced scar size. These animals also showed an increase in levels of neurons and NG2, a decrease in levels of astrocytes and a significant functional recovery as assessed using the BBB locomotor scale at 2 weeks post-treatment.ConclusionsThe improvement in locomotor recovery and decrease in scar size shows the potential of this gene therapy approach as a therapeutic treatment for SCI.     

Renal effects of dopamine and ANP in high volume expanded rats

Both dopamine (DA) and atrial natriuretic peptide (ANP) have been postulated to exert similar effects on the kidney, participating in the regulation of body fluid and sodium homeostasis. In the present study, experiments were performed in anesthetized and isotonic sodium chloride volume expanded rats. After acute volume expansion at 15 % of body weight during 30 min, glomerular filtration rate, urine output, sodium excretion, fractional sodium excretion, proximal and distal sodium excretion and blood pressure were measured. In additional groups we administered ANP or haloperidol or the combination of both to volume expanded animals. Blockade of DA receptors with haloperidol, attenuated diuretic and natriuretic responses to volume load. Proximal sodium excretion was not modified by haloperidol in all experimental groups of rats. Reduction in distal tubular excretion was induced by haloperidol in saline infusion expanded rat but not in ANP treated expanded animals. In conclusion, when exaggerated volume expansion is provoked, both DA and ANP exert renal tubular events, but ANP have a major central role in the regulation of renal sodium handling.     

Thoracic Rat Spinal Cord Contusion Injury Induces Remote Spinal Gliogenesis but Not Neurogenesis or Gliogenesis in the Brain

After spinal cord injury, transected axons fail to regenerate, yet significant, spontaneous functional improvement can be observed over time. Distinct central nervous system regions retain the capacity to generate new neurons and glia from an endogenous pool of progenitor cells and to compensate neural cell loss following certain lesions. The aim of the present study was to investigate whether endogenous cell replacement (neurogenesis or gliogenesis) in the brain (subventricular zone, SVZ; corpus callosum, CC; hippocampus, HC; and motor cortex, MC) or cervical spinal cord might represent a structural correlate for spontaneous locomotor recovery after a thoracic spinal cord injury. Adult Fischer 344 rats received severe contusion injuries (200 kDyn) of the mid-thoracic spinal cord using an Infinite Horizon Impactor. Uninjured rats served as controls. From 4 to 14 days post-injury, both groups received injections of bromodeoxyuridine (BrdU) to label dividing cells. Over the course of six weeks post-injury, spontaneous recovery of locomotor function occurred. Survival of newly generated cells was unaltered in the SVZ, HC, CC, and the MC. Neurogenesis, as determined by identification and quantification of doublecortin immunoreactive neuroblasts or BrdU/neuronal nuclear antigen double positive newly generated neurons, was not present in non-neurogenic regions (MC, CC, and cervical spinal cord) and unaltered in neurogenic regions (dentate gyrus and SVZ) of the brain. The lack of neuronal replacement in the brain and spinal cord after spinal cord injury precludes any relevance for spontaneous recovery of locomotor function. Gliogenesis was increased in the cervical spinal cord remote from the injury site, however, is unlikely to contribute to functional improvement.     

伸长细胞移植对大鼠脊髓损伤后运动功能及运动诱发电位的影响

目的:研究伸长细胞是否可以促进成年大鼠脊髓损伤后传导束再生。方法:采用Wistar大鼠脊髓T8全横断模型,移植传代培养的伸长细胞,以未移植脊髓损伤组为对照,观察两组损伤后第12周末BBB评分,损伤平面以下红核-脊髓运动诱发电位,和横断部位组织学染色结果。结果:第12周末伸长细胞移植组红核脊髓运动诱发电位总峰值显著高于对照组(MD=133.2μV,P0.01),峰潜伏期较对照组缩短(MD=0.061ms,P=0.040);第12周末伸长细胞移植组BBB评分显著高于对照组(MD=5.0000,P0.01);第12周末脊髓横断部位HE染色显示伸长细胞移植组脊髓损伤处结构较完整。结论:伸长细胞移植可以促进大鼠脊髓损伤后神经传导的恢复。     

Characteristics of capsaicin-sensitive afferent neurons of spinal nerve ganglia

Morphological peculiarities of neurons that had TRPV1, SP, CGRP, and NF200 markers in thoracic spinal ganglia nerves were studied in 3-month-old rats subjected to chemical deafferentation produced by capsaicin. The obtained results have shown that from 6.5 to 41.3% of ganglion neurons in the control group of animals contain, as a rule, one of the above-mentioned markers. The heterogeneity of nociceptive neurons observed in a control group of rats was also preserved in the capsaicin-treated animals. In both groups, the spinal ganglion TRPV1 neurons were predominant, whereas populations of SP, CGRP, and NF200 neurons formed smaller groups. In each population, sensitivity to capsaicin was shown in the largest neurons, regardless of marker; this sensitivity was pronounced to the greatest degree in the group of TRPV1 neurons.     

Fluoro-Jade B evidence of induced ischemic tolerance in the rat spinal cord ischemia: physiological, neurological and histopathological consequences

Fluoro-Jade B, a marker of degenerating neurons, was used to label histopathological changes in the rat spinal cord after transient ischemia and ischemic preconditioning (IPC). To characterize postischemic neurodegenerations and consequent neurological changes, a particular attention was paid to the standardization of ischemic conditions in animals of both groups. 1. The control ischemic rats were submitted to a reversible occlusion of descending aorta by insertion and subsequent inflation of a 2F Fogarty catheter for 12 min. 2. In the IPC rats, an episode of short 3 min occlusion and 30 min reperfusion preceded the 12 min ischemia. Postischemic motor function testing (ambulation and stepping) was provided repeatedly for evaluation of neurological status 2 h and 24 h after surgery and at the end of postischemic survival, i.e. after 48 h. Fluoro-Jade B staining was used to demonstrate degenerated neurons. In the control rats, neurological consequences of histopathological changes in lumbosacral spinal cord, manifested as paraplegia, were present after 12 min ischemia. Thus, numbers of degenerated Fluoro-Jade B positive cells were visible in gray matter of the most injured L(4)-S(2) spinal cord segments. Slight motor function impairment, consequential from significant decreasing in Fluoro-Jade B-positivity in the L(4)-S(2) spinal cord segments of the IPC rats, was considered the pathomorpfological evidence that IPC induces spinal cord tolerance to ischemia. Our results are consistent with the previously published silver impregnation method for histopathological demonstration of ischemic degeneration.     

Genetic identification of spinal interneurons that coordinate left-right locomotor activity necessary for walking movements

The sequential stepping of left and right limbs is a fundamental motor behavior that underlies walking movements. This relatively simple locomotor behavior is generated by the rhythmic activity of motor neurons under the control of spinal neural networks known as central pattern generators (CPGs) that comprise multiple interneuron cell types. Little, however, is known about the identity and contribution of defined interneuronal populations to mammalian locomotor behaviors. We show a discrete subset of commissural spinal interneurons, whose fate is controlled by the activity of the homeobox gene Dbx1, has a critical role in controlling the left-right alternation of motor neurons innervating hindlimb muscles. Dbx1 mutant mice lacking these ventral interneurons exhibit an increased incidence of cobursting between left and right flexor/extensor motor neurons during drug-induced locomotion. Together, these findings identify Dbx1-dependent interneurons as key components of the spinal locomotor circuits that control stepping movements in mammals.     

Rat behavior in the "open field" next day after haloperidol injection: dependence on experimental conditions

Wistar rats were injected with haloperidol (3.5 mg/kg) that resulted in a high level of cataplexy. Next day after haloperidol injection rat behavior was studied in the open field. The animals were divided in two groups. The first group of animals was tested in the daylight without additional illumination of the open-field chamber. The second group was tested in a darkened room with additional intense illumination of the open-field center with a 60W bulb. The testing time was 240 s. The high level of the open-field locomotor activity in the first group was attributed to anxiety. The low level of locomotor activity in the second group was qualified as depressive state.     

Effect of Capsaicin Pretreatment on Substance P Binding to Synaptic Vesicles

Newborn or adult rats were pretreated with 50 mg kg-1 capsaicin. At the age of 2 to 4 months, binding of 125I-labelled Tyr8-substance P to synaptic vesicles prepared from different regions of the nervous system was examined. In both groups, capsaicin pretreatment led to a significant decrease in the number of binding sites in dorsal roots and spinal cord without having an effect on affinity. This decrease parallels the depletion of the substance P content (Gamse et al., 1980) and can be explained by degeneration of primary sensory neurons in newborn treated rats and by depletion of vesicles in adult treated rats.     

Versatile robotic interface to evaluate, enable and train locomotion and balance after neuromotor disorders

Central nervous system (CNS) disorders distinctly impair locomotor pattern generation and balance, but technical limitations prevent independent assessment and rehabilitation of these subfunctions. Here we introduce a versatile robotic interface to evaluate, enable and train pattern generation and balance independently during natural walking behaviors in rats. In evaluation mode, the robotic interface affords detailed assessments of pattern generation and dynamic equilibrium after spinal cord injury (SCI) and stroke. In enabling mode,the robot acts as a propulsive or postural neuroprosthesis that instantly promotes unexpected locomotor capacities including overground walking after complete SCI, stair climbing following partial SCI and precise paw placement shortly after stroke. In training mode, robot-enabled rehabilitation, epidural electrical stimulation and monoamine agonists reestablish weight-supported locomotion, coordinated steering and balance in rats with a paralyzing SCI. This new robotic technology and associated concepts have broad implications for both assessing and restoring motor functions after CNS disorders, both in animals and in humans.     

Bauhinia forficata Prevents Vacuous Chewing Movements Induced by Haloperidol in Rats and Has Antioxidant Potential In Vitro

Classical antipsychotics can produce motor disturbances like tardive dyskinesia in humans and orofacial dyskinesia in rodents. These motor side effects have been associated with oxidative stress production in specific brain areas. Thus, some studies have proposed the use of natural compounds with antioxidant properties against involuntary movements induced by antipsychotics. Here, we examined the possible antioxidant activity of Bauhinia forficata (B. forficata), a plant used in folk medicine as a hypoglycemic, on brain lipid peroxidation induced by different pro-oxidants. B. forficata prevented the formation of lipid peroxidation induced by both pro-oxidants tested. However, it was effective against lipid peroxidation induced by sodium nitroprusside (IC₅₀ = 12.08 μg/mL) and Fe²⁺/EDTA (IC₅₀ = 41.19 μg/mL). Moreover, the effects of B. forficata were analyzed on an animal model of orofacial dyskinesia induced by long-term treatment with haloperidol, where rats received haloperidol each 28 days (38 mg/kg) and/or B. forficata decoction daily (2.5 g/L) for 16 weeks. Vacuous chewing movements (VCMs), locomotor and exploratory activities were evaluated. Haloperidol treatment induced VCMs, and co-treatment with B. forficata partially prevented this effect. Haloperidol reduced the locomotor and exploratory activities of animals in the open field test, which was not modified by B. forficata treatment. Our present data showed that B. forficata has antioxidant potential and partially protects against VCMs induced by haloperidol in rats. Taken together, our data suggest the protection by natural compounds against VCMs induced by haloperidol in rats.     

Differential effects of chronic treatment with haloperidol and clozapine on the level of preprosomatostatin mRNA in the striatum,nucleus accumbens,and frontal cortex of the rat

1. The goal of this work was to determine the effects of typical and atypical neuroleptics on the level of preprosomatostatin messenger RNA (mRNA) in regions of the rat brain innervated by dopaminergic neurons. 2. Quantitative in situ hybridization histochemistry was used to measure the levels of mRNA encoding preprosomatostatin in neurons of the striatum, the nucleus accumbens, and the medial and lateral agranular areas of the frontal cortex in adult rats treated with either haloperidol or clozapine. 3. In untreated animals, the density of neurons containing preprosomatostatin mRNA was higher in the nucleus accumbens than in the striatum and frontal cortex. The intensity of labeling per neuron, however, was higher in the striatum than in the two other areas examined, suggesting that the expression of preprosomatostatin mRNA is differentially regulated in these brain regions. Chronic administration of haloperidol (1 mg/kg for 28 days) induced a significant decrease in the labeling for preprosomatostatin mRNA in neurons of the nucleus accumbens, frontal cortex, and medial but not lateral striatum. Treatment with clozapine (20 mg/kg for 28 days) increased the levels of preprosomatostatin mRNA in the nucleus accumbens but not in the striatum or the frontal cortex. 4. These results support a role for dopamine in the regulation of central somatostatinergic neurons. The differences in the effects of haloperidol, a neuroleptic which induces extrapyramidal side effects, and clozapine, which does not, suggest that somatostatinergic neurons may play an important role in the regulation of motor behavior.     

Neonatal fluoxetine exposure alters motor performances of adolescent rats

Growing evidence from human and animal studies has shown adverse consequences of maternal usage of antidepressants in their newborn babies. To study the effects of early antidepressant exposure on motor function later in life, we treated neonatal rat pups with fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI)-type antidepressant, from the day of birth to postnatal day 4 and examined motor performance during adolescence. FLX-treated rats had reduced locomotor activities in an open field and poorer motor performance on an accelerating rotarod compared to the control group of saline-treated animals. Nevertheless, the poorer motor performance largely improved after repetitive practices. To elucidate the structural alterations in the motor system, we examined the structure of neurons in motor-related brain regions. The shape, density, and soma size of cerebellar Purkinje cells were comparable in the two groups, however, density of dendritic spine in medial spiny neurons of striatum and Layer 5 pyramidal neurons in the primary motor cortex (M1) were reduced in FLX-rats. Furthermore, the basilar dendrites in M1 Layer 5 neurons had reduced dendritic complexity than those of the control animals. The impaired dendritic structure in striatal and cortical neurons in FLX-treated rats might account for their poorer motor performances. Together, the structure and function of the motor system are affected by early FLX exposure, the long-term effects of early exposure to SSRI-type antidepressants should be concerned.