PLASMATIC LEVELS OF NEUROPEPTIDES, INCLUDING OXYTOCIN, IN CHILDREN WITH AUTISM SPECTRUM DISORDER, CORRELATE WITH THE DISORDER SEVERITY.

CONTEXT: Oxytocin has been investigated as a potential medication for psychiatric disorders. OBJECTIVE AND DESIGN: This study prospectively investigates correlations between oxytocin and other neuropeptides plasma levels in patients with autism spectrum disorders (ASD) according to severity and treatment, as compared to controls. SUBJECTS AND METHODS: Thirty-one children (6 neurotypical as control) participated in this study. The patients were classified into mildly and severely-affected, according to Autism Diagnostic Observation Schedule (ADOS) scores. Oxytocin, orexin A and B, α-MSH, ß-endorphins, neurotensin and substance P were investigated using a quantitative multiplex assay or a competitive-ELISA method. RESULTS: Plasma oxytocin levels differed between the groups (F (2, 24) =6.48, p=0.006, η2=0.35, observed power=86%): patients with the mild ASD had higher values of plasma oxytocin than those with the severe form (average difference=74.56±20.74pg/mL, p=0.004). CONCLUSIONS: These results show a negative correlation between plasma levels of oxytocin and the severity of ASD and support the involvement of oxytocinergic mechanisms in ASD.

RETINAL MICROCIRCULATION INVESTIGATION IN TYPE I AND II DIABETIC PATIENTS WITHOUT RETINOPATHY USING AN ADAPTIVE OPTICS RETINAL CAMERA.

CONTEXT: State of art imaging techniques might be a useful tool to early detect the retinal vessels lesions in diabetes. OBJECTIVE AND DESIGN: This analytical observational study investigates the retinal microcirculation changes in type I and II diabetic patients without retinopathy using adaptive optics ophthalmoscopy (AOO) and optical coherence ophthalmoscopy angiography (OCTA). SUBJECTS AND METHODS: Fifty-five subjects were included in this study and were divided in three groups: type I diabetic group (n=16), type II diabetic group (n=19) and control group (n=20). An adaptive optics retinal camera was used to assess the parameters of the temporal superior retinal arterioles. Moreover, vessel density of the superficial capillary plexus across the parafoveal area was measured with OCT-A. All cases were investigated once, in a cross-sectional design. RESULTS: Diabetic patients from both groups had a higher wall-to-lumen-ratio compared to the controls (p=0.01 and 0.01, respectively). Interestingly, no significant differences were found between the two diabetic groups (p=0.69). Moreover, the vessel density was smaller in the type I diabetic group than in the control group (p=0.001). CONCLUSION: AOO might be a useful tool to detect early retinal vascular changes in diabetes before any clinical signs and together with OCTA it might bring important information on the prognostic and pathophysiology of the disease.

OXYTOCIN REDUCES SEIZURE BURDEN AND HIPPOCAMPAL INJURY IN A RAT MODEL OF PERINATAL ASPHYXIA.

CONTEXT: Foetal asphyxia, a frequent birth complication, detrimentally impacts the immature brain, resulting in neuronal damage, uncontrolled seizure activity and long-term neurological deficits. Oxytocin, a neurohormone mediating important materno-foetal interactions and parturition, has been previously suggested to modulate the immature brain's excitability, playing a neuroprotective role. Our aim was to investigate the effects of exogenous oxytocin administration on seizure burden and acute brain injury in a perinatal model of asphyxia in rats. ANIMALS AND METHODS: Asphyxia was modelled by exposing immature rats to a 90-minute episode of low oxygen (9% O2) and high CO2 (20% CO2). Control rats were kept in ambient room-air for the same time interval. In a third group of experiments, oxytocin (0.02 UI/g body weight) was nasally administered 30 minutes before the asphyxia episode. Seizure burden was assessed by the cumulative number of loss of righting reflex (LRR) over a two-hour postexposure period. Acute brain injury was assessed through hippocampal S-100 beta, a biomarker of cellular injury, 24-hours after exposure. RESULTS: Asphyxia increased both LRR and hippocampal S-100 beta protein compared to controls, and these effects were significantly reduced by oxytocin administration. CONCLUSION: Oxytocin treatment decreased both seizure burden and hippocampal injury, supporting a potential neuroprotective role for oxytocin in perinatal asphyxia.

PRELIMINARY INSIGHTS IN OXYTOCIN ASSOCIATION WITH THE ONSET OF DIABETIC NEUROPATHY.

Diabetes is one of the most prevalent chronic disorders, associating numerous somatic and behavioral modifications. Oxytocin has been widely studied for its involvement in social behavior and psychiatric disorders. This pilot study presents a series of 3 patients with type 1 diabetes and diabetic neuropathy in which the values of plasma oxytocin, neurotensin, ß-endorphins, α-MSH, substance P and orexin A were measured in comparison to 3 healthy controls with matching ages. In the diabetic patients group, there was a strong negative correlation between the value of plasma glucose and oxytocin (r=-0.99, p=0.04), respectively neurotensin (r=-0.99, p=0.03). These values did not correlate in the control group. The results suggest that oxytocin, in conjunction with neurotensin, could be investigated as a potential early detection marker of diabetic neuropathy and, to our knowledge, this is the first report focusing on plasma oxytocin levels in patients with diabetic neuropathy.

Effects of caffeine on locomotor activity in streptozotocin-induced diabetic rats.

Diabetes mellitus modifies the expression of adenosine receptors in the brain. Caffeine acts as an antagonist of A1 and A2A adenosine receptors and was shown to have a dose-dependent biphasic effect on locomotion in mice. The present study investigated the link between diabetes and locomotor activity in an animal model of streptozotocin-induced diabetes, and the effects of a low-medium dose of caffeine in this relation. The locomotor activity was investigated by using Open Field Test at 6 weeks after diabetes induction and after 2 more weeks of chronic caffeine administration. Diabetes decreased locomotor activity (total distance moved and mobility time). Chronic caffeine exposure impaired the locomotor activity in control rats, but not in diabetic rats. Our data suggested that the medium doses of caffeine might block the A2A receptors, shown to have an increased density in the brain of diabetic rats, and improve or at least maintain the locomotor activity, offering a neuroprotective support in diabetic rats. Abbreviations: STZ = streptozotocin, OFT = Open Field Test.

The association between Diabetes mellitus and Depression.

UNLABELLED: Depression occurrence is two to three times higher in people with diabetes mellitus, the majority of the cases remaining under-diagnosed. The purpose of this review was to show the links between depression and diabetes, point out the importance of identifying depression in diabetic patients and identify the possible ways to address both diseases. Possible common pathophysiological mechanisms as stress and inflammation were explained, while emphasis was made on screening for depression in diabetic patients. An important aspect for the diabetic specialist would be the understanding of the common origins of diabetes and depression and the awareness of this quite common comorbidity, in order to improve the outcomes of both diseases. ABBREVIATIONS: DALYS = disability adjusted life years, DSM-5 = American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, DM1 = Type 1 diabetes mellitus, DM2 = Type 2 diabetes mellitus, HPA-axis = hypothalamus - pituitary - adrenal axis, SNS = sympathetic nervous system, BDI = Beck Depression Inventory, CES-D = Centre for Epidemiologic Studies Depression Scale, HADS = Hospital Anxiety and Depression Scale, PHQ = Patient Health Questionnaire.

Impact of chronic administration of anabolic androgenic steroids and taurine on blood pressure in rats.

Supraphysiological administration of anabolic androgenic steroids has been linked to increased blood pressure. The widely distributed amino acid taurine seems to be an effective depressor agent in drug-induced hypertension. The purpose of this study was to assess the impact of chronic high dose administration of nandrolone decanoate (DECA) and taurine on blood pressure in rats and to verify the potentially involved mechanisms. The study was conducted in 4 groups of 8 adult male Wistar rats, aged 14 weeks, treated for 12 weeks with: DECA (A group); vehicle (C group); taurine (T group), or with both drugs (AT group). Systolic blood pressure (SBP) was measured at the beginning of the study (SBP1), 2 (SBP2) and 3 months (SBP3) later. Plasma angiotensin-converting enzyme (ACE) activity and plasma end products of nitric oxide metabolism (NOx) were also determined. SBP3 and SBP2 were significantly increased compared to SBP1 only in the A group (P<0.002 for both). SBP2, SBP3 and ACE activity showed a statistically significant increase in the A vs C (P<0.005), andvs AT groups (P<0.05), while NOx was significantly decreased in the A and AT groups vs controls (P=0.01). ACE activity was strongly correlated with SBP3 in the A group (r=0.71, P=0.04). These findings suggest that oral supplementation of taurine may prevent the increase in SBP induced by DECA, an effect potentially mediated by angiotensin-converting enzyme.

CHRONIC CAFFEINE'S EFFECTS ON BEHAVIOURAL CHANGES IN STREPTOZOTOCIN-INDUCED DIABETIC RATS.

CONTEXT: Memory deficits, anxiety and depression are often associated with diabetes, worsening diabetic patients' prognosis. Caffeine, a worldwide used psychoactive substance, is a candidate for improving these conditions. OBJECTIVE: The aim of this study was to assess the behaviour in streptozotocin-induced diabetic Wistar rats and to evaluate the behavioural effects of caffeine administration. MATERIALS AND METHODS: Diabetes was induced by a single intraperitoneal injection of 50 mg/kg BW streptozotocin (n=10), while control rats received the vehicle (n=9). After six weeks, behavioural tests for anxiety, memory and depression were performed: elevated plus maze (EPM) test, novel object recognition (NOR) test and forced swimming test (FST), respectively. The tests were repeated after further 2 weeks of continuous caffeine administration (20 mg/kg BW/day in drinking water). RESULTS: Diabetic rats manifested a high anxiety level, showed by a reduced exploratory activity compared to control rats (p<0.05) and long-term memory impairment, spending more time near the old object in NOR test. Caffeine administered for 2 weeks did not modify glycemic values in either group, and attenuated the behavioural changes observed in the EPM test. Also, in NOR test for long-term memory, caffeine administration induced an increased time spent with the novel object than with the old one in both groups. CONCLUSIONS: Our data suggest that chronic caffeine administration has an anxiolytic effect in diabetic rats and improves long-term memory in both diabetic and control rats.

Impact of chronic administration of anabolic androgenic steroids and taurine on blood pressure in rats

Supraphysiological administration of anabolic androgenic steroids has been linked to increased blood pressure. The widely distributed amino acid taurine seems to be an effective depressor agent in drug-induced hypertension. The purpose of this study was to assess the impact of chronic high dose administration of nandrolone decanoate (DECA) and taurine on blood pressure in rats and to verify the potentially involved mechanisms. The study was conducted in 4 groups of 8 adult male Wistar rats, aged 14 weeks, treated for 12 weeks with: DECA (A group); vehicle (C group); taurine (T group), or with both drugs (AT group). Systolic blood pressure (SBP) was measured at the beginning of the study (SBP1), 2 (SBP2) and 3 months (SBP3) later. Plasma angiotensin-converting enzyme (ACE) activity and plasma end products of nitric oxide metabolism (NOx) were also determined. SBP3 and SBP2 were significantly increased compared to SBP1 only in the A group (P<0.002 for both). SBP2, SBP3 and ACE activity showed a statistically significant increase in the A vs C (P<0.005), andvs AT groups (P<0.05), while NOx was significantly decreased in the A and AT groups vs controls (P=0.01). ACE activity was strongly correlated with SBP3 in the A group (r=0.71, P=0.04). These findings suggest that oral supplementation of taurine may prevent the increase in SBP induced by DECA, an effect potentially mediated by angiotensin-converting enzyme.

Impact of maternal melatonin suppression on forced swim and tail suspension behavioral despair tests in adult offspring.

Melatonin is an essential hormone, which regulates circadian rhythms and has antioxidative and anticarcinogenic effects. As melatonin secretion is suppressed by light, this effect was examined on the offspring of the Wistar rat females exposed to continuous light (500 lux) during the second half of the pregnancy (day 12 to 21). Control rats were kept under a 12:12 light-dark cycle. The resulted male offspring have been behaviorally assessed for depression after postnatal day 60 by using Forced Swim Test (FST) and Tail Suspension Test (TST). Animals resulted from the melatonin deprived pregnancies have developed an abnormal response in the TST, but a normal FST behavior. Also, TST active movement was different in the melatonin suppression group compared to the control group. These findings suggest that intrauterine melatonin deprivation might be linked to the depressive like behavior in adult male offspring.

Fronto-parietal connectivity changes following noxious stimulation during anesthesia.

RATIONALE: The aim of our study was to assess the changes in the fronto-parietal connectivity estimated by the cross approximate entropy (XAppEn) during noxious stimulation while under chloral hydrate anaesthesia, in rats. METHOD: A group of 11 Wistar rats chronically implanted with Ni-Cr electrodes, which were placed on the dura mater of the right hemisphere (over the olfactory cortex, the frontal and the parietal lobes), were used in the present study. Noxious stimuli of a mechanical and thermal nature were applied on the left hindpaw during chloral hydrate anesthesia. The anesthetic depth was estimated through median frequency computation, which in that instance was of 2-3 Hz. Fronto-parietal functional cortical connectivity was assessed by using XAppEn. RESULTS: After data processing and analysis we observed an increase of fronto-parietal functional connectivity during mechanical and thermal noxious stimulation. In addition, MEF increased both in frontal and parietal areas during the mechanical and thermal stimulation compared to baseline. CONCLUSION: Mechanical and thermal stimulation induces an increase in the fronto-parietal connectivity during chloral hydrate anesthesia in rats.

Effect of diet and omega-3 fatty acids in NAFLD.

Nonalcoholic fatty liver disease (NAFLD) ranges from simple hepatic steatosis to steatohepatitis (NASH) and cirrhosis. The aim of this study is to test beneficial effects of omega-3 fatty acids (DHA 130 mg, EPA 25 mg) treatment in NAFLD, in a mouse model of non-alcoholic fatty liver disease. As pretreatment, 50 mice were fed for one month with a high-fat diet to induce NAFLD. Then, the mice were divided in different groups according to diet (normo- or hypercaloric), with and without treatment with omega-3 fatty acids, for another month, forming the post-treatment group. The liver and blood samples were collected for biochemical and histopathological analysis. Biochemical parameters including: glycemia, total cholesterol, triglycerides, uric acid, albumin, total plasma antioxidant capacity (TEAC) was measured in serum. Glutathione (GSH), total thiols and malonyldialdehyde (MDA) were determined in mouse liver homogenates. Mice from post-treatment group, on hypercaloric diet with or without omega-3 fatty acids treatment, had medium hepatopathy (granular and vacuolar degeneration of the hepatocytes) and hypertriglyceridemia. Omega-3 fatty acid treatment lowered the rise of triglycerides (p<0.03), glycemia (p<0.01) and cholesterol (p<0.02) in serum and MDA level of the liver (p<0.05). Mice from post-treatment group, on normocaloric diet with or without omega-3 fatty acid had different histopathological and biochemical results. Those with normocaloric/normolipidic diet and omega-3 fatty acids treatment had reversed liver histopathological results from NASH to normal aspect and had the best metabolic parameters results. In conclusion, omega-3 fatty acids treatment associated with a normocaloric/normolipidic diet has hepatoprotective action in nonalcoholic fatty liver disease.

Electrophysiological changes in optic neuropathy of streptozotocin induced diabetic rats.

UNLABELLED: The visually evoked potentials are electrical signals generated by the occipital cortex due to electrical stimulus. The clinical importance of VEP is to diagnose the functional changes of the optic nerve in different diseases such as diabetic mellitus. Our study sought latency of VEP changes depending on glycemic value and duration of diabetes in Wistar rats. METHODS: this study evaluated the VEP of 25 rats in three groups: control group, diabetic group 1 with glycemic values between 200-400mg/dl and diabetic group 2 with glycemic values between 400 and 600mg/dl. These rats from diabetic group 2 were followed for 4 months and the ones in control group and diabetic group 1 for 5 months. RESULTS: the latency of VEP shows slight changes without any statistical significance in the control group. In diabetic group 1 and 2 similar changes occurred, with statistical significance and the amplitude of the changes was proportional with the glycemic value. The rats had a rapid increase of VEP latency after the induction of diabetes and returned to a normal range in the first month. After a time, when the latencies of VEP were in normal range, a new growth appeared faster and larger as the glycemic values were higher. CONCLUSION: diabetes brings changes to the visual signal transmission and to the central processing, this being revealed by the examination of the visually evoked potential. Increased VEP latency is statistically correlated with the changes that occur at the level of the values of glucose in blood. A rapid growth in blood sugar lowers the visual signal transmission. This change is temporary despite the persistence of elevated blood glucose values, probably by adjusting to the new condition. However, maintaining high glycemic values remotely produces a progressive increase of the delay of the visual signal. This progressive increase is faster as blood glucose levels are higher.

Analysis of the visual evoked potential in anesthesia with sevoflurane and chloral hydrate : (Variability of amplitudes, latencies and morphology of VEP with the depth of anesthesia).

UNLABELLED: The visually evoked potential (VEP) is an electrical signal generated by the occipital cortex in response to light stimulation of the retina. The clinical importance of the VEP consists in the diagnosis of optic nerve diseases and others ocular diseases. For experimental studies of VEP in experimental animals anesthesia is frequently required. Our study sought VEP changes depending on the type and depth of anesthesia. METHODS: this study evaluated VEPs in 20 Wistar rats under two anesthetics. Ten rats were anesthetized with sevoflurane and ten rats with chloral hydrate. RESULTS: The amplitudes, latencies and morphology of the VEP varied with the depth of anesthesia. The latency of VEP increases with the depth of anesthesia and the amplitude of the waves becomes more positive once the anesthesia decreases under sevoflurane and more negative under chloral hydrate. The variability of VEP was different under the two anesthetics with greater peak latencies under sevoflurane than under chloral hydrate at the same depth of anesthesia. IN CONCLUSION: it is important to know the influence of the anesthetic and the depth of anesthesia over VEPS, because they may constitute a confounding factor in studying VEP in different diseases of optic nerve or eyeball.

Endogenous activation of adenosine A1 receptors promotes post-ischemic electrocortical burst suppression.

Following transient global cerebral ischemia (GCI), spontaneous electrocortical activity resumes from the isoelectric line through a sequence of "bursts" of activity alternating with periods of electrical "suppression," commonly referred to as the post-ischemic burst suppression (BS) pattern. Several lines of evidence suggest that BS reflects an impairment of neocortical connectivity. Here we tested in vivo whether synaptic depression by adenosine A1 receptor (A1R) activation contributes to BS patterns following GCI. Male Wistar rats were subjected to 1, 5 or 10 min of GCI using a "four-vessel occlusion" model under chloral hydrate anesthesia. Quantification of BS recovery was carried out using BS ratio. During GCI full electrocortical suppression was attained (BS ratio reached 100%). During the following reperfusion the BS ratio returned to 0. The time course of the decay was exponential after 1 and 5-min GCI and bi-exponential after 10-min GCI. The BS recovery was progressively delayed with the duration of ischemia. Administration of the A1R antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 1.25 mg/kg i.p.) accelerated the post-ischemic BS recovery for all GCI durations. Following the 10-min GCI the effect of DPCPX was only apparent on the initial fast decay of the BS ratio. These data suggest that endogenous adenosine release promotes BS patterns during reperfusion following transient cerebral ischemia. Furthermore, the endogenous A1R activation may be the primary underlying cause of post-ischemic BS patterns following brief ischemic episodes. It is likely that synaptic depression by post-ischemic A1R activation functionally disrupts the connectivity within the cortical networks to an extent that promotes BS patterns.

C-kit immunopositive interstitial cells (Cajal-type) in human myometrium.

Previous reports describing Cajal-like interstitial cells in human uterus are contradictory in terms of c-kit immunoreactivity: either negative (but vimentin-positive) in pregnant myometrium, or positive, presumably in the endometrium. The aim of this study was to verify the existence of human myometrial Cajal-like interstitial cells (m-CLIC). Six different, complementary approaches were used: 1) methylene-blue supravital staining of tissue samples (cryosections), 2) methylene blue and Janus green B vital staining (m-CLIC and mitochondrial markers, respectively), and 3) extracellular single-unit electrophysiological recordings in cell cultures, 4) non-conventional light microscopy on glutaraldehyde/osmium fixed, Epon-embedded semi-thin sections (less than 1 microm) stained with toluidine blue (TSM), 5) transmission electron microscopy (TEM), and 6) immunofluorescence (IF). We found m-CLIC in myometrial cryosections and in cell cultures. In vitro, m-CLIC represented approximately 7% of the total cell number. m-CLIC had 2-3 characteristic processes which were very long (approximately 60 microm), very thin (< or =0.5 microm) and moniliform. The dilated portions of processes usually accommodated mitochondria. In vitro, m-CLIC exhibited spontaneous electrical activity (62.4+/-7.22 mV membrane potentials, short duration: 1.197+/-0.04 ms). Moreover, m-CLIC fulfilled the usual TEM criteria, the so-called 'gold' or 'platinum' standards (e.g. the presence of discontinuous basal lamina, caveolae, endoplasmic reticulum, and close contacts between each other, with myocytes, nerve fibers and/or capillaries etc.). IF showed that m-CLIC express CD117/c-kit, sometimes associated with CD34, with vimentin along their processes. In conclusion, we describe myometrial Cajal-like interstitial cells that have affinity for methylene blue and Janus green B vital dyes, fulfill (all) TEM criteria, express CD117/c-kit and have spontaneous electric activity.

Novel type of interstitial cell (Cajal-like) in human fallopian tube.

We describe here--presumably for the first time--a Cajal-like type of tubal interstitial cells (t-ICC), resembling the archetypal enteric ICC. t-ICC were demonstrated in situ and in vitro on fresh preparations (tissue cryosections and primary cell cultures) using methylene-blue, crystal-violet, Janus-Green B or MitoTracker-Green FM Probe vital stainings. Also, t-ICC were identified in fixed specimens by light microscopy (methylene-blue, Giemsa, trichrome stainings, Gomori silver-impregnation) or transmission electron microscopy (TEM). The positive diagnosis of t-ICC was strengthened by immunohistochemistry (IHC; CD117/c-kit+ and other 14 antigens) and immunofluorescence (IF; CD117/c-kit+ and other 7 antigens). The spatial density of t-ICC (ampullar-segment cryosections) was 100-150 cells/mm2. Non-conventional light microscopy (NCLM) of Epon semithin-sections revealed a network-like distribution of t-ICC in lamina propria and smooth muscle meshwork. t-ICC appeared located beneath of epithelium, in a 10-15 microm thick 'belt', where 18+/-2% of cells were t-ICC. In the whole lamina propria, t-ICC were about 9%, and in muscularis approximately 7%. In toto, t-ICC represent ~8% of subepithelial cells, as counted by NCLM. In vitro, t-ICC were 9.9+/-0.9% of total cell population. TEM showed that the diagnostic 'gold standard' (Huizinga et al., 1997) is fulfilled by 'our' t-ICC. However, we suggest a 'platinum standard', adding a new defining criterion- characteristic cytoplasmic processes (number: 1-5; length: tens of microm; thickness: < or =0.5 microm; aspect: moniliform; branching: dichotomous; organization: network, labyrinthic-system). Quantitatively, the ultrastructural architecture of t-ICC is: nucleus, 23.6+/-3.2% of cell volume, with heterochromatin 49.1+/-3.8%; mitochondria, 4.8+/-1.7%; rough and smooth endoplasmic-reticulum (1.1+/-0.6%, 1.0+/-0.2%, respectively); caveolae, 3.4+/-0.5%. We found more caveolae on the surface of cell processes versus cell body, as confirmed by IF for caveolins. Occasionally, the so-called 'Ca2+-release units' (subplasmalemmal close associations of caveolae+endoplasmic reticulum+mitochondria) were detected in the dilations of cell processes. Electrophysiological single unit recordings of t-ICC in primary cultures indicated sustained spontaneous electrical activity (amplitude of membrane potentials: 57.26+/-6.56 mV). Besides the CD117/c-kit marker, t-ICC expressed variously CD34, caveolins 1&2, alpha-SMA, S-100, vimentin, nestin, desmin, NK-1. t-ICC were negative for: CD68, CD1a, CD62P, NSE, GFAP, chromogranin-A, PGP9.5, but IHC showed the possible existence of (neuro)endocrine cells in tubal interstitium. We call them 'JF cells'. In conclusion, the identification of t-ICC might open the door for understanding some tubal functions, e.g. pace-making/peristaltism, secretion (auto-, juxta- and/or paracrine), regulation of neurotransmission (nitrergic/purinergic) and intercellular signaling, via the very long processes. Furthermore, t-ICC might even be uncommitted bipotential progenitor cells.

Electro-cortical signs of early neuronal damage following transient global cerebral ischemia in rat.

During recovery after a transient global cerebral ischemia (TGCI), rat electrocorticogram (ECoG) shows epochs of synchronized activity (SA) alternating with epochs of low amplitude background activity (BA). The aim of this study was to compare the changes in these electrical activities during a 30-min recovery period that followed either a non-injuring (3 minutes, N=10) or an injuring (10 minutes, N=10) TGCI. During TGCI there was a 3 fold reduction in amplitudes of both SA and BA but no changes in frequency. During reperfusion following a 3 minutes TGCI, the amplitudes of both SA and BA recovered to about 70%. During the reperfusion that followed a 10 minutes TGCI, BA showed no recovery, whereas SA recovered to about 40%. During the 30 min reperfusion, there was a time-dependent decrease in the frequency of SA, but independent on the duration of TGCI. In contrast, the frequency of the BA did not change during reperfusion. Our data indicate that following cerebral ischemia the recovery of SA can take place independently of BA. The lack of recovery in BA may indicate early subcortical neuronal damage.

The relationship between respiratory sinus arrhythmia and heart rate during anesthesia in rat.

During inspiration the heart rate (HR) increases and during expiration it decreases. Contribution of respiratory sinus arrhythmia (RSA) to spontaneous heart rate variability (HRV) can be measured as the high frequency (HF) component of variation in consecutive R-R intervals on ECG. In conscious rats, slowing of HR is associated with an increase in HF. The aim of this study was to investigate whether this relationship between HF and HR is preserved during anesthesia in rat. A 15 minutes long ECG signal was recorded from rats (N=15) under moderate chloral hydrate (CHL) anesthesia. Recordings were extended with 45 minutes to investigate the effect of atropine (N=3), against controls (N=3). Short term HRV was investigated in 30 seconds long epochs. HF was considered the frequency band between 0.8 and 1.6 Hz. RSA was quantified as the relative spectral power of the HF. Respiratory frequency (RF) was quantified as the mean spectral frequency within the HF band. One minute estimates of HR, RSA and HF were calculated by averaging 3 epochs of 30 seconds overlapped 50%. The average HR was 427 +/- 3 bpm. The magnitude of RSA was 45 +/- 1% at a RF of 71 +/- 1 rpm. We found that: (1) the decrease in HR that occurs during CHL anesthesia in rat correlates with an increase in RSA; (2) atropine reduces RSA and the time-dependent decrease in HR; (3) the time-dependent increase in RSA is preserved after atropine. We conclude that the correlation between RSA and HR reflects the cardio-pulmonary coupling under parasympathetic control.

Oxidative damage following cerebral ischemia depends on reperfusion - a biochemical study in rat.

The extent of brain injury during reperfusion appears to depend on the experimental pattern of ischemia/reperfusion. The goals of this study were: first, to identify the rate of free radicals generation and the antioxidant activity during ischemia and reperfusion by means of biochemical measurement of lipid peroxidation (LPO) and both enzymatic (superoxide dismutase - SOD, catalase - CAT, glutathione peroxidase - GPx) and non-enzymatic antioxidants activity (glutathione - GSH); and second, to try to find out how the pattern of reperfusion may influence the balance between free radical production and clearance. Wistar male rats were subject of four-vessel occlusion model (Pulsinelly & Brierley) cerebral blood flow being controlled by means of two atraumatic arterial microclamps placed on carotid arteries. The level of free radicals and the antioxidant activity were measured in ischemic rat brain tissue homogenate using spectrophotometrical techniques. All groups subjected to ischemia shown an increase of LPO and a reduction of the activity of enzymatic antioxidative systems (CAT, GPx, SOD) and non-enzymatic systems (GSH). For both groups subjected to ischemia and reperfusion, results shown an important increase of LPO but less significant than the levels found in the group with ischemia only. Statistically relevant differences (p<0.01) between continuous reperfusion and fragmented reperfusion were observed concerning the LPO, CAT, SOD and GSH levels, oxidative aggression during fragmented reperfusion being more important.