Exposure of developing well-nourished and malnourished rats to environmental heating facilitates cortical spreading depression propagation at adulthood

Cortical spreading depression (CSD) is a brain electrical response related to neural activity and probably also related to diseases like migraine and epilepsy. Adverse conditions like malnutrition and exposure to a warm environment early-in-life can permanently alter brain development, changing electrophysiological features of the brain responses and rendering the brain prone to febrile seizures. Here we investigated the lasting effects of heat exposure on brain CSD propagation in well-nourished and malnourished developing rats. From postnatal days 10–29, rats were exposed to daily sessions (one session per day, five sessions per week during 3 weeks; total of 15 sessions) of a warm environment (40 ± 2 °C). At 30–40 days and 90–120 days of life (young and adult age-ranges, respectively), they were anesthetized (urethane + chloralose; 1000 + 40 mg/kg ip) and the electrocorticogram plus the slow potential change accompanying CSD were recorded on two parietal points for 4 h. Compared to controls (maintained on the normal environment temperature, 23 ± 2 °C), heat-exposed rats displayed higher CSD velocities of propagation (P < 0.05; ANOVA plus Tukey test) at both age-ranges and nutritional statuses. The mean ± S.D. CSD velocities (in mm/min) were: for control- and heat-exposed well-nourished rats, 3.75 ± 0.15 and 4.17 ± 0.19 (young groups), and 3.33 ± 0.06 and 3.88 ± 0.26 (adult); for the same control and heat exposure conditions in the malnourished rats, 4.30 ± 0.22 and 5.31 ± 0.46 (young), and 4.18 ± 0.20 and 4.88 ± 0.35 (adult). In contrast to early malnutrition, heat exposure did not affect body and brain weights. Data support the hypotheses that (1) early heat exposure long-lasting facilitates CSD propagation and (2) this effect is not modified by early malnutrition.     

Chronic treatment with ascorbic acid enhances cortical spreading depression in developing well-nourished and malnourished rats

Ascorbic acid (AA) is an antioxidant molecule that is highly concentrated in the brain and can exert both anticonvulsant and proconvulsant effects in distinct models of experimental seizures. Herein, we investigated whether chronic AA administration alters cortical excitability as indexed by the cortical spreading depression (CSD). Well-nourished (W) and malnourished (M) rats were treated, by gavage, with 60 mg/kg/day of l-AA from postnatal days 7–28, and CSD propagation was analyzed at 30–40 days. Compared to the W groups, M rats presented higher (p < 0.05) CSD amplitudes and velocities of propagation. In both nutritional conditions, AA-treatment significantly increased CSD amplitudes and propagation velocities (p < 0.05), as compared to non-treated (‘naïve’; Nv) and saline-treated (Sal) controls. The mean ± standard deviation CSD velocities of propagation (in mm/min) for the Sal, AA and Nv groups were respectively 3.75 ± 0.03, 4.26 ± 0.08 and 3.81 ± 0.04 for the W condition and 4.29 ± 0.08, 4.51 ± 0.04 and 4.30 ± 0.04 for the M groups. The results demonstrate a CSD-facilitation by AA regardless of nutritional status. They also suggest that, at the dose of 60 mg/kg/day chronically administered during brain development, AA may act as a prooxidant in brain, in view of the contrasting effect as compared with other antioxidants, which reduce CSD.     

Direct evidence of inter-hemispheric modulation by callosal fibers: a cortical spreading depression study in well-nourished and early-malnourished adult rats

Inter-hemispheric modulation has been extensively studied, as it is critical for human behavior and could be involved in the development of neuropsychiatric disorders, such as major depression, epilepsy and stroke. Malnutrition early in life can alter brain processes such as inter-hemispheric modulation and these alterations can persist into adulthood. Here, we used cortical spreading depression (CSD) as a neurophysiological parameter to investigate inter-hemispheric modulation in 19 well-nourished and 18 early-malnourished male adult rats. CSD was evoked on the right frontal region and monitored at two parietal points on the same hemisphere. After a 2 h baseline recording, fibers projecting from the left to the right hemisphere via the corpus callosum were cut with a longitudinal lesion in the contralateral cortex and recording continued for two more hours. The results show that (1) baseline CSD propagation velocities were higher in the malnourished rats, as compared to the respective well-nourished controls; (2) post-lesion velocities increased in both nutritional groups, as compared with the baseline values; (3) this CSD increase persisted 3–7 days after lesion, suggesting a lasting effect and (4) in the malnourished group the post-lesion CSD enhancement was of smaller amplitude. Furthermore, a midline lesion (callosotomy) in eight well-nourished rats similarly facilitated CSD, suggesting the involvement of callosal fibers on this effect. No differences were found in sham-operated rats (21 well-nourished and 21 malnourished), as well as in a superficial (1 mm deep) contralateral lesion group (8 well-nourished). Results support the hypothesis of a lasting inhibitory contralateral influence on CSD propagation, which is attenuated, but not abolished, by early malnutrition.     

Infrared LED light therapy influences the expression of fibronectin and tenascin in skin wounds of malnourished rats—A preliminary study

The aim of this investigation was to evaluate the effect of infrared (λ 846 ± 20 nm) LED irradiation on the expression profile of the extracellular matrix protein components, tenascin and fibronectin on skin wounds induced in well nourished and malnourished rats. Eighteen albino rats (21 days old) were randomly divided into a well-nourished group (standard diet) and a malnourished group (regional basic diet). After receiving the diet for 70 days, skin wounds were created and the animals were subdivided into three groups: well-nourished control (n = 6), malnourished control (n = 6), and malnourished + LED irradiated (λ 846 ± 20 nm, 100 mW, 4 J/cm²) (n = 6). The animals were sacrificed 3 and 7 days after injury and histological sections were immunostained for both proteins. They were examined for the presence, intensity, distribution and pattern of immunolabeling. At 3 days, the distribution of tenascin was shown to be greater in the wound bed of malnourished animals compared to the well-nourished group. The intensity and distribution of tenascin was shown to be lower in the malnourished LED irradiated group compared to the malnourished control. There was a significant difference regarding the presence of fibronectin in the malnourished and well-nourished groups after 7 days (p = 0.03). The intensity of fibronectin was slight (100%) in the irradiated group and moderate to intense in the malnourished control group. The results of the present study indicate that infrared LED irradiation modulates positively the expression of tenascin and particularly fibronectin.     

Sleep-deprivation enhances in adult rats the antagonistic effects of pilocarpine on cortical spreading depression: A dose–response study

Conditions that facilitate epilepsy, such as sleep deprivation or the cholinergic muscarinic agonist pilocarpine (PILO), have been experimentally studied, as they are relevant for brain excitability control and could help in understanding the development of epilepsy in humans. In this work, following to 72 h deprivation (D) of sleep by the water tank technique, adult Wistar rats were anesthetized with a 1 g/kg urethane + 40 mg/kg chloralose mixture and cortical spreading depression (CSD) was recorded for a 1–2 h period in the parietal surface. CSD propagation velocity was calculated based on the time spent for a CSD-wave to pass the interelectrode distance. After this “baseline” recording, D-animals were divided in three groups and respectively injected with 45, 95 and 190 mg/kg of PILO, i.p., and the CSD recording continued for two more hours. Three groups of non-deprived (ND) rats were also injected with the three doses of PILO and studied regarding CSD features. D-animals presented higher baseline CSD velocities than the corresponding ND-controls, confirming previous observations that D-condition facilitates CSD propagation. After PILO, the ECoG amplitudes were markedly and lastingly reduced in all animals, at the three doses used. In the groups treated with 95 and 190 mg/kg PILO, the CSD velocity of propagation significantly (P < 0.05) decreased, and the incidence of PILO-associated CSD-propagation failure increased in the D rats, but not in the ND rats, as compared with the pre-drug values. The data suggest the existence of one or more cholinergic, muscarinic-mediated antagonistic processes influencing CSD, which are dose-dependent and are modulated by sleep-deprivation.     

Sympathoinhibition to Bezold–Jarisch reflex is attenuated in protein malnourished rats

Malnutrition affects cardiovascular reflexes, including chemoreflex and baroreflex. In this study we assessed the hypothesis that malnourishment changes the responses in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) evoked from Bezold–Jarisch reflex (BJR). Fischer rats were fed diets containing either (6% malnourished or 14% control) protein for 35 days after weaning. There were no differences in baseline MAP (102 ± 4 vs. 95 ± 3 mmHg) whereas higher baseline HR (478 ± 18 vs. 360 ± 11 bpm; P < 0.05,) and reduced sympathoinhibition (ΔRSNA = −54 ± 9 vs. −84 ± 7%; P = 0.0208) to BJR activation were found in malnourished rats. We conclude that malnutrition affects the sympathetic control of BJR.     

Large litters rearing changes brain expression of GLUT3 and acetylcholinesterase activity in adult rats

Effects of malnutrition in the brain are more pronounced during the period of growth spurt, corresponding to the suckling in rodents. Neuronal glucose transporter GLUT3 expression and acetylcholinesterase activity were studied in the brain of adult young rats (84 days old) suckled in litters formed by 6 (control group) or 12 pups (malnourished group). In the adult rats, brain weight, blood glucose levels and GLUT3 expression were decreased in malnourished group (5%, 18%, 58%, respectively, P < 0.001, Student's t test) compared to the control. Increased activity of acetylcholinesterase was found in cerebral cortex homogenates and a significant interaction (P = 0.019, ANOVA two-way, Tukey's test) was found between nutritional state and homogenate fraction. In summary, malnutrition during suckling period decreased GLUT3 expression and increased acetylcholinesterase activity in the rat brain that could contribute to possible cognitive deficits and changes of brain metabolic activity.     

Delayed peripheral administration of the N-terminal tripeptide of IGF-1 (GPE) reduces brain damage following microsphere induced embolic damage in young adult and aged rats

We have previously reported that peripheral administration of GPE prevents neuronal injury after ischemic reperfusion injury in young adult rats. This study examined the ameliorating effects of GPE-treatment after embolic injury induced by microsphere injection in young adult and aged male rats. Unilateral injury was induced by injecting microspheres into the right internal carotid artery in both young adult (3–4 months) and aged (16–17 months) male rats. Either GPE (12 mg/kg) or the vehicle was infused intravenously over 1 h starting 3 h after embolic injury and the degree of brain injury, astrocytosis and vascular remodeling were examined using histological and immunohistochemical analysis 8 days later. Changes in core temperature, blood glucose concentration, oxygen saturation and heart rate were monitored. Microsphere injection induced multiple sites of focal damage in the ipsilateral subcortical regions. Massive numbers of microglia accumulated within the core of the tissue damage whereas astrocytes were located in the penumbra. There was no difference in the degree of brain injury between the young and aged control rats. However the aged rats showed less injury-induced astrocytosis and greater vascular remodeling. Intravenous infusion of GPE 3 h after the injury reduced overall damage scores in both young (p < 0.01) and aged rats (p < 0.05). GPE-treatment reduced astrocytosis in young, but not aged animals and did not significantly alter the vascular remodeling in either age group. The data suggested that the neuroprotection of the tripeptide is independent of cerebral reperfusion and is not age selective.     

Effects of short-term and long-term treatment with medium- and long-chain triglycerides ketogenic diet on cortical spreading depression in young rats

The ketogenic diet (KD) is a high fat and low carbohydrate and protein diet. It is used in the clinical treatment of epilepsy, in order to decrease cerebral excitability. KD is usually composed by long-chain triglycerides (LCT) while medium-chain triglycerides (MCT) diet is beginning to be used in some clinical treatment of disorders of pyruvate carboxylase enzyme and long-chain fatty acid oxidation. Our study aimed to analyze the effects of medium- and long-chain KD on cerebral electrical activity, analyzing the propagation of the phenomenon of cortical spreading depression (CSD). Three groups of weaned rats (21 days old) received, for 7 weeks, either a control (AIN-93G diet), or a MCT-KD (rich in triheptanoin oil), or a LCT-KD (rich in soybean oil). They were compared to another three groups (21 days old) receiving the same diets for just 10 days. CSD propagation was evaluated just after ending the dietary treatments. Results showed that short-term KD treatment resulted in a significant reduction of the CSD velocity of propagation (control group: 4.02 ± 1.04 mm/min; MCT-KD: 0.81 ± 1.46 mm/min and LCT-KD: 2.26 ± 0.41 mm/min) compared to the control group. However, long-term treatment with both KDs had no effect on the CSD velocity (control group: 3.10 ± 0.41 mm/min, MCT-KD: 2.91 ± 1.62 mm/min, LCT-KD: 3.02 ± 2.26 mm/min) suggesting that both short-term KDs have a positive effect in decreasing brain cerebral excitability in young animals. These data show for the first time that triheptanoin has an effect on central nervous system.     

Effects of early aging and cerebral hypoperfusion on spreading depression in rats

Cortical spreading depression (CSD) is a feature of stroke pathophysiology. As stroke incidence increases with age, we have examined the effects of early aging and chronic cerebral hypoperfusion on CSD in rats.Three groups were studied: Young, 2-month-old animals; Middle-aged-2VO, subjected to 8 months of bilateral carotid occlusion from 2-month-of-age; and Middle-aged-SHAM, sham-operated. At 2- and 10-month-of-age for the Young and Middle-aged groups, recurrent CSD were induced under halothane anesthesia, by sustained application of 1 M KCl to the cortex for 2 h. Propagating CSD (i.e., cortical EEG, direct current potential) and associated laser Doppler blood flow changes were recorded anteriorly.Susceptibility to CSD and event duration were both decreased by early aging (frequency: 21 ± 0.5 and 6 ± 0.5 CSD/h; duration: 139 ± 7 and 63 ± 8 s; in Young and Middle-aged-SHAM, respectively). There was also a tendency for CSD-associated hyperemia to be reduced in the Middle-aged-2VO group (8.9 ± 2.1 vs. 32.8 ± 12.6% × min in Young). These data suggest reduced sensitivity of the cortex to CSD elicitation with early aging, and a less responsive cerebrovascular system with chronic hypoperfusion.     

Early treadmill training promotes motor function after hemorrhagic stroke in rats

Rehabilitation after a stroke is very important because it has beneficial effects on brain function, including the promotion of plasticity. However, an optimal time window for rehabilitation interventions after hemorrhagic stroke has not been clearly defined. The aim of this study was to determine whether early exercise training initiated 24 h after an intracerebral hemorrhage (ICH) might enhance neurologic recovery more than exercise initiated 1 week after ICH without hematoma expansion and edema volume increase. We subjected adult male Sprague–Dawley rats to experimental ICH by the intrastriatal administration of bacterial collagenase. The rats were randomly divided into the following 2 groups: early training group (treadmill exercise started 24 h post-ICH; n = 18) and late training group (treadmill exercise started 1-week post-ICH; n = 18). Two weeks after surgery we performed neurologic tests (rota-rod, modified limb-placing, and adhesive-dot removal tests), and measured hematoma volumes and brain water content. In the late training group, compared with the pre-ICH performance on the rota-rod test (98.3 ± 69.4 s), the animals had significantly worse performance after the post-ICH rehabilitation (40.5 ± 52.6 s; p < 0.01, paired t-test). In the early training group however, the motor performance after the post-ICH rehabilitation (56.4 ± 73.5 s) was not significantly different from the baseline pre-ICH performance (79.8 ± 33.9 s; p = 0.24). There were no significant differences between the two groups with respect to the other neurologic tests. Early exercise did not increase hematoma size or brain water content. Early treadmill training could be performed safely, and enhanced motor recovery in a rat model of ICH. Further studies are required to translate the results into clinical significance.     

Toward the development of a sensitive,pre-clinical screen for neurological diseases from spontaneous neural coordination in juvenile and young–adult C57BK6 mice

Spontaneous Frequency Bursts (SFBs) are a newly discovered form of long-distance neural coordination. They have several distinctive properties, including near-simultaneity of occurrence (±25–50 ms) across distant brain regions and high within- and across-site coherence in multiple low and high frequency bands, presumably requiring high axonal, dendritic and vascular integrity. We examined whether SFBs occurred in young and young–adult C57BK6 mice with properties similar to those seen in rats. We found that across the entorhinal and piriform cortices, SFBs occur robustly in young and young–adult mice under light anesthesia, and that their rate of occurrence dropped sharply as anesthetic levels increased, as in rats. Moreover, murine SFBs showed high cross-site coherence in multiple frequency bands, including those that require exquisite action potential timing to be maintained across long distances. We discuss our findings in light of SFBs potential as a pre-clinical biomarker for diseases affecting action potential firing and local field potential coherence, especially in high frequency ranges (20–30 Hz and beyond).     

Long-lasting resistance to haloperidol-induced catalepsy in male rats chronically treated with caffeine

Chronic caffeine consumption has been inversely associated with the risk of developing Parkinson's disease. Here we assessed whether chronic caffeine treatment increases the resistance of male Wistar rats to haloperidol (1 mg/kg, s.c.)-induced catalepsy, measured in the bar test at 15 min intervals during 3 h. Caffeine (5 mg/kg/day) was delivered for 6 months via drinking water. Control rats received only tap water. Treatments began when animals were 3–4 months old. In order to unveil long-lasting catalepsy refractoriness not attributable to the presence of caffeine in the brains of rats, they were evaluated from day 18 to day 27 after caffeine withdrawal, a time that is far in excess for the full excretion of a caffeine dose in this species. The average cataleptic immobility measured in caffeine-treated rats (n = 23) was 1148 ± 140 s, a value 34 ± 8% lower than that recorded in control animals (n = 20), whose mean immobility was 1736 ± 137 s (P = 0.0026, t-test). The percentage of catalepsy reduction measured in caffeine-treated rats evaluated on days 18–20 after caffeine discontinuation (−32 ± 13%, n = 12, P < 0.05) was comparable to the catalepsy decrease recorded in those animals tested on days 21–27 (−36 ± 10%, n = 11, P < 0.02), a finding compatible with the notion that the effect was indeed mediated by enduring changes of brain functioning and not by the physical presence of caffeine or its metabolites. Caffeine-treated rats also had higher catalepsy latency scores compared with control rats (P < 0.01, U-test). The present findings show that chronic consumption of caffeine produces perdurable resistance to catalepsy induced by dopamine receptor blockade, possibly through enhancement of dopamine transmission, giving further support to the epidemiological results indicating that prolonged caffeine consumption affords neuroprotection against Parkinson's disease.     

Anxiety-like behavior in weanling and young adult male and female malnourished rats

The present study determined whether protein-calorie malnutrition alters anxiety-like behavior in weanling and young adult, male and female malnourished rats. On the day of birth, litters of Wistar rats were divided into Control (C) and Malnutrition (M) groups. In the C group, litters were fed by dams receiving ad libitum lab chow, whereas in the M group, litters were fed by dams receiving 40% of the total amount of the diet offered to dams in the C group. After weaning (PND21) until PND50, animals received the same food as theirs mothers (i.e., ad libitum access in the C group and 40% of the C group food in the M group). On PND21 and PND50, independent C (male [CM] and female [CF]) and M (male [MM] and female [MF]) groups were exposed to the elevated T-maze. The time taken to withdraw four paws from this arm was recorded (baseline latency [BL]). The same measurement was repeated twice at 30 s intervals (avoidance trial 1 [AT1] and avoidance 2 [AT2]). The cutoff time in each trial was 300 s. ANOVA indicated a four-way age × diet × sex × trials interaction. Post hoc comparisons revealed that PND50 rats had a lower BL and AT1 latency compared with PND21 rats. Training increased both AT1 and AT2 latencies compared with BL in both the CM and CF groups. Weanling malnourished rats exhibited reduced anxiety-like behavior and young adult male rats presented less anxiety-like behavior than young adult female rats in this experimental model.     

Early postnatal protein malnutrition changes the development of social play in rats

Early protein malnutrition produces structural and functional alterations in the brain and changes the organism-environment interactions. Rats from 26 to 76 days of age were used to study the effects of early postnatal protein malnutrition on the development of social play. During lactation phase the litters were fed diet containing 16% protein (well-nourished) or 6% protein (malnourished). From weaning to the end of behavioral tests well-nourished animals were fed a commercial lab chow diet (well-nourished--W) and the malnourished rats were divided into 2 groups: one was maintained on 6% protein diet (malnourished--M) and the other was fed a commercial lab chow diet (previously malnourished--PM). Pairs of male rats of same diet conditions were tested, at different ages, for three consecutive days. During sessions the following behaviors were recorded: pinning, wrestling, walk-over and rear. The frequency of wrestling and walk-over was significantly higher in malnourished as compared to well-nourished animals (p<0.05). Early protein malnutrition also changed the ontogeny of play behaviors (pinning and wrestling) with developmental retards in M and PM as compared with W animals, especially at 46 and 56 days of age. These results suggest that early protein malnutrition can affect the development of neural mechanisms underlying social play in rats.     

Cerebral transplantation of encapsulated mesenchymal stem cells improves cellular pathology after experimental traumatic brain injury

Purpose: “Naked” human mesenchymal stem cells (MSC) are neuro-protective in experimental brain injury (TBI). In a controlled cortical impact (CCI) rat model, we investigated whether encapsulated MSC (eMSC) act similarly, and whether efficacy is augmented using cells transfected to produce the neuro-protective substance glucagon-like peptide-1 (GLP-1). Methods: Thirty two Sprague–Dawley rats were randomized to five groups: controls (no CCI), CCI-only, CCI + eMSC, CCI + GLP-1 eMSC, and CCI + empty capsules. On day 14, cisternal cerebro-spinal fluid (CSF) was sampled for measurement of GLP-1 concentration. Brains were immuno-histochemically assessed using specific antibody staining for NeuN, MAP-2 and GFAP. In another nine healthy rats, in vitroResults: GLP-1 production rates were measured from cells explanted after 2, 7 and 14 days. GLP-1 production rate in transfected cells, before implantation, was 7.03 fmol/capsule/h. Cells were still secreting GLP-1 at a rate of 3.68 ± 0.49, 2.85 ± 0.45 and 3.53 ± 0.55 after 2, 7 and 14 days, respectively. In both of the stem cell treated CCI groups, hippocampal cell loss was reduced, along with an attenuation of cortical neuronal and glial abnormalities, as measured by MAP-2 and GFAP expression. The effects were more pronounced in animals treated with GLP-1 secreting eMSC. This group displayed an increased CSF level of GLP-1 (17.3 ± 3.4 pM). Conclusions: Hippocampal neuronal cell loss, and cortical glial and neuronal cyto-skeletal abnormalities, after CCI are reduced following transplantation of encapsulated eMSC. These effects were augmented by GLP-1 transfected eMSC.     

The differential effects of equipotent doses of isoflurane and desflurane on hippocampal acetylcholine levels in young and aged rats

The differential effects of age-adjusted equipotent doses of isoflurane (Iso) and desflurane (Des) on hippocampal acetylcholine (ACh) levels were examined using cerebral microdialysis in young (12–16 weeks old) and aged (16–18 months old) Fischer 344 rats. An 80 min exposure to 1 minimum alveolar concentration (MAC) of isoflurane and desflurane produced similar maximal decreases in hippocampal ACh levels in both age groups: to 36.3 ± 13.9% (Iso) and 28.6 ± 12.9% (Des) of baseline in aged rats versus 32.5 ± 18.7% (Iso) and 29.6 ± 12.5% (Des) of baseline in young rats. Compared to isoflurane, the onset of this maximal decrease was delayed in both age groups with desflurane. Furthermore, following the end of anesthesia in aged rats, hippocampal ACh levels returned to control levels faster with desflurane (within 20–40 min) than isoflurane (within 60–80 min). These data demonstrate that age-adjusted equipotent doses of isoflurane and desflurane produce similar maximal decreases in hippocampal ACh levels in a manner that is independent of age. However, compared to isoflurane, desflurane is associated with a slower decrease in and a faster restoration of hippocampal ACh levels following anesthesia in this rat model of aging. Hence, in the aged, the administration of age-adjusted equipotent doses of an inhalational anesthetic with low blood and tissue solubility, such as desflurane, may provide a viable pharmacotherapeutic strategy for minimizing the duration of the attenuation of hippocampal cholinergic outflow observed following anesthesia.     

Effects of prenatal protein malnutrition on the electrical cerebral activity during development

Early protein restriction during the prenatal period has significant repercussions on the ontogeny and development of the central nervous system. The present study investigates whether early prenatal protein malnutrition could alter the electrical cerebral activity of the progeny. We used Sprague–Dawley female rats of 200 g randomly divided into three groups: a control group that received a diet with 25% of the protein content (lactalbumin), the experimental group, that received a diet with 6% of the protein content and the rehabilitated group that initially received a diet with 6% of the protein content, then switched to a diet with 25% of the protein content after the weaning period (P20D) up to 60 days of life (P60D). Reduction of the protein content from 25% to 6% of lactalbumin in the diet of pregnant rats produces impairment in the electrical cerebral activity in the progeny at P20D and at P60D. The power spectral analysis for each one of the electroencephalograms revealed that prenatal protein malnutrition in rats produced a significant reduction of the alpha (8–13 Hz) and the beta bands (13–30 Hz) and a significant increase of the theta (4–8 Hz), and delta bands (1–4 Hz), at two different stages of life (P20D and P60D). Similar results were obtained for the rehabilitated group. These results indicate that early malnutrition in life affects the ontogeny of the electrical cerebral activity. This insult probably disrupts the establishment of cortical neural circuits during the critical period of brain development. The rehabilitation period did not revert the impairment in the electrical cerebral activity produced by malnutrition. We used one-way ANOVA analysis, followed by Tukey test (*p < 0.001).     

Investigating the effects of adult neural stem cell transplantation by lumbar puncture in transient cerebral ischemia

Stem cells have the ability to self renew and are therefore a good source for cell therapy following ischemia. In this study, we transplanted adult rat neural stem cells (NSCs) by lumbar puncture (LP) to investigate whether these cells can migrate and differentiate into neurons or glial cells, thereby improving functional outcome in cerebral ischemia. Transient ischemia was induced in adult rats (n = 16) for 1 h. Three days after the induction of ischemia, NSCs obtained from the subventricular zone of adult rats were injected into ischemic animals (n = 8) by LP at the level of L6–S1. Improved recovery of the coordination of movement on the 1st, 7th, 14th, 21st and 28th days after the injury was examined by the Rotarod test and compared with non-transplanted ischemic animals (n = 8). The presence of NSCs in the brain tissue of the animals was examined by immunohistofluorscence and immunohistochemical techniques. The coordination of movement in ischemic animals that received neural stem cells was improved significantly (P < 0.05) compared with untreated ischemic animals. Cells labeled with PKH26 were observed in the ischemic area of brain tissue sections. The alkaline phosphatase test and immunohistochemical techniques demonstrated a gathering of NSCs in the lateral ventricle. A number of cells which expressed neuronal and astrocytic cell markers had migrated from the lateral ventricle to the subjacent brain parenchyma. NSCs injected by LP were able to migrate to the ischemic tissue and differentiate into neural-like cells. These differentiated cells may have improved the coordination in movement in the ischemic animals injected with NSCs.     

Commissural NTS lesions enhance the pressor response to central cholinergic and adrenergic activation

Electrolytic lesions of the commissural nucleus of the solitary tract (commNTS) in rats enhance the pressor response to bilateral carotid occlusion or to intravenous infusion of hypertonic NaCl without changing baroreflex responses. In an opposite direction, commNTS lesions abolish the pressor responses to peripheral chemoreflex activation. These opposite effects of commNTS lesions apparently result from an impairment of sympathetic activation in one case and in a facilitation of vasopressin secretion in the others. In the present study, we investigated the effects of the electrolytic lesions of the commNTS in the pressor responses that depend on sympathetic activation and vasopressin secretion produced by central cholinergic or adrenergic activation with intracerebroventricular (i.c.v.) injections of carbachol or noradrenaline, respectively, in unanesthetized rats. Male Holtzman rats (280–320 g, n = 8–15/group) with acute (1 day) or chronic (21 days) sham or commNTS lesions (1 mA × 10 s) and a stainless steel cannula implanted in the lateral ventricle were used. Acute commNTS lesions increased the pressor response to i.c.v. injection of carbachol (0.5 nmol/1 μ1) (52 ± 2, vs. sham: 37 ± 2 mmHg) or noradrenaline (80 nmol/1 μl) (45 ± 6, vs. sham: 30 ± 3 mmHg), whereas chronic commNTS lesions did not affect the pressor responses to the same treatments. Lesions of the commNTS impaired chemoreflex responses produced by intravenous KCN, without changing baroreflex responses. The results suggest that commNTS-dependent inhibitory signals are involved in the modulation of the pressor responses to central cholinergic and adrenergic activation, probably limiting vasopressin secretion.