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PubMed1990

Relationship between plasma catecholamine levels and electrocortical state in the mature fetal lamb.

In late pregnancy the electrocortical activity (ECoG) in the ovine fetus starts to cycle between high and low voltage states. During the high voltage states of this activity fetal regional blood flows are decreased, and heart rate and fetal arterial blood pressure are both increased. Jensen et al. (1986) have postulated that these changes may be mediated by changes in autonomic tone. To test this hypothesis we placed catheters in 6 near-term sheep fetuses (gestational age = 128 days) and implanted electrodes to measure electrocortical activity. Five days after the surgery, fetal arterial blood was withdrawn during the first 3-5 min of each high and low voltage ECoG for 5 full cycles in each fetus. Plasma samples were analyzed for epinephrine, norepinephrine, and dopamine. Dopamine levels were not different in high and low voltage electrocortical state. In the high voltage ECoG state, epinephrine levels were 75 +/- 7 pg/ml and fell to 34 +/- 4 pg/ml during low voltage ECoG (P less than 0.01). During the high voltage state plasma norepinephrine was 623 +/- 85 pg/ml and fell during the low voltage period to 462 +/- 99 pg/ml (P less than 0.01). These data demonstrate that in the near-term sheep fetus plasma catecholamine levels fluctuate with ECoG state.

Animals↗

PubMed1989

Indomethacin antagonizes the ethanol-induced suppression of breathing activity but not the suppression of brain activity in the near-term fetal sheep.

The effect of indomethacin on the ethanol-induced suppression of fetal breathing movements, low-voltage electrocortical (ECoG) activity, and electro-ocular (EOG) activity was studied in the near-term fetal sheep. Ten conscious instrumented pregnant ewes (between 129 and 131 days of gestation; term, 147 days) received 1-h maternal intravenous infusion of 1 g ethanol/kg total body weight and simultaneous fetal treatment with either indomethacin (2 mg/kg fetal body weight/h) (n = 5) or an equivalent volume of phosphate buffer (n = 5) intravenously for 9 h. Fetal ECoG activity, EOG activity, and fetal breathing movements were monitored continuously over the experimental periods. In animals treated with ethanol and buffer (n = 5), fetal breathing movements were suppressed for 8 h and low-voltage ECoG and EOG activity was suppressed for 2 h below preinfusion levels. In animals treated with ethanol and indomethacin (n = 5), fetal breathing movements were elevated for 13 h but low-voltage ECoG and EOG activity remained suppressed for 3 h below preinfusion levels. The data suggests that indomethacin can antagonize the ethanol-induced suppression of fetal breathing movements, but does not alter the ethanol-induced suppression of ECoG or EOG activity.

Animals↗

PubMed1988

Electrocochleography: methods and clinical applications.

The use of electrocochleography (ECoG) as a tool in the diagnosis, assessment, and monitoring of certain neuro-otologic disorders has attracted renewed attention in the United States. The use of ECoG among otologists and audiologists has increased in recent years, primarily due to the availability of relatively easily applied, noninvasive extratympanic electrodes. Information derived from ECoG recordings has been shown to be helpful in the objective identification and monitoring of Meniere's disease and endolymphatic hydrops. In addition, ECoG may be used to enhance our ability to observe the most peripheral component of the auditory brain stem response (Wave I) for routine clinical assessment or during intraoperative monitoring procedures in which certain structures of the ear are at risk for permanent damage. This article provides an overview of current techniques and clinical applications of ECoG.

Audiometry, Evoked Response↗

PubMed1988

Anticonvulsive effect of 2-hydroxylamine-5-ethyl-5-sec-pentyl barbituric acid (HB-7) in two experimental models of epilepsy.

The effects of barbiturate HB-7 (2-hydroxylamine-5-ethyl-5-sec-pentylbarbituric acid) injected intraperitoneally compared to the effects of pentobarbital and/or phenobarbital were investigated in three series of experiments on cats: normal electrocorticogram (ECoG); pentylentetrazol-induced generalized paroxysmal ECoG; and paroxysmal ECoG activity induced by topical application of penicillin on the exposed cortical surface. In the first series, HB-7 led to the appearance of ECoG spindles of the same type as those elicited by pentobarbital. In the second series (pentylentetrazol-treated group), HB-7 increased the two thresholds: one associated with the appearance of isolated paroxysmal spike-wave complexes and the other corresponding to the appearance of generalized paroxysmal ECoG activity. In the third series, HB-7 led to an inhibition of penicillin spikes, both in the focus itself and in the other cortical areas where they propagated. The possibility for using HB-7 as an antiepileptic drug was discussed.

Animals↗

PubMed1995

Prognostic factors for survival in patients with metastatic renal cancer treated with biological response modifiers.

PURPOSE: Clinical characteristics prognostic of survival in patients with metastatic renal cell carcinoma treated with biological response modifiers are poorly understood. Understanding these prognostic features may help with better stratification of patients in clinical trials and define further appropriate treatment for each prognostic subgroup. MATERIALS AND METHODS: A retrospective study of 84 patients with recurrent or metastatic renal cancer was conducted to identify prognostic factors for survival in patients who received biological response modifiers (alpha-interferon, beta-interferon, gamma-interferon and interleukin-2). RESULTS: Univariate analysis identified Eastern Cooperative Oncology Group (ECOG) performance status (1 versus 0, p < 0.001), bone metastasis (p = 0.008), recent weight loss (greater than 10% of total body weight versus no loss, p = 0.028), history of nephrectomy (no versus yes, p = 0.025), recurrence at the renal bed (p = 0.043) and sarcomatoid histology (yes versus no, p < 0.001) as important prognostic indicators. Multivariate analysis of prognostic factors in this patient population indicated that ECOG performance status, sarcomatoid histology and bone metastasis were most significant, while other factors were less significant (p > 0.05) after adjusting for ECOG performance status and sarcomatoid histology. Based on the total positive number of 5 risk factors defined previously the study population separates into 3 risk groups, with a median survival from the low to high risk groups of 14.4, 10.9 and 1.3 months, respectively. Prognostic scores based only on ECOG performance status, sarcomatoid histology and bone metastasis allowed for stratification of our patients into 3 distinct groups with median survivals of 18.6, 8.4 and 3.8 months, which were also predictive of survival (p < 0.05). CONCLUSIONS: Risk factors of ECOG performance status, sarcomatoid histology, bone metastasis, history of nephrectomy, recent weight loss and recurrence at the renal bed are predictive of survival in patients treated with biological response modifiers. In addition to previous findings of prognostic factors in renal cancer patients treated with chemotherapy, we identified sarcomatoid histology as an important risk factor in patients treated with biological response modifiers.

Bone Neoplasms↗

PubMed1996

Electrocorticographic activity during repeated vs continuous hypoxia in piglets.

To assess the effects on brain activity of repeated vs continuous hypoxia, 16, 10- to 22-day-old piglets were instrumented chronically for electrocortical and arterial pH and gas tension measurements. They inhaled 10% or 6% O2 in N2 for 21 min, either continuously, or during seven, 3 min exposures interrupted by 3 min recovery periods in air, all while behaving naturally within a sealed, temperature controlled, plexiglass box. An isoelectric electrocorticogram (ECoG) and/or seizures, related to the onset of hypoxia, occurred repeatedly in 6 of the 10 exposures to 6% repetitive hypoxia, only twice in 8 exposures to 6% continuous hypoxia, and never in 10% hypoxia. A frequency analysis of the ECoG, excluding all sections exhibiting isoelectric and seizure activity, revealed no changes with 10% hypoxia, but a shift towards the lower bands during both repetitive and continuous 6% hypoxia. The extent of these shifts was greater in records that also displayed isoelectric ECoG and/or seizures. The ECoG spectrum recovered at the end of the hypoxic exposure, but not when isoelectric ECoG and/or seizures coexisted. We conclude that repeated, frequent episodes of hypoxia are more detrimental than a prolonged single event, and may contribute to the occurrence of Sudden Infant Death.

Animals↗

PubMed1990

Survival of premenopausal women with metastatic breast cancer. Long-term follow-up of Eastern Cooperative Group and Cancer and Leukemia Group B studies.

In premenopausal women with metastatic breast cancer, differences in survival curves early during follow-up can be misleading. The authors therefore analyzed long-term survival in 378 patients, entered in three randomized trials, started between 1973 and 1978. Combined data from the three trials were used to increase the power for identifying prognostic variables. Cancer and Leukemia Group B (CALGB) trial 7382 randomized patients to oophorectomy plus either cyclophosphamide or combination chemotherapy or observation. Eastern Cooperative Oncology Group (ECOG) 2174 randomized patients who had not progressed 3 months after oophorectomy to combination chemotherapy or combination chemotherapy or observation. Trial ECOG 2177 randomized estrogen receptor (ER) positive or ER-unknown patients to oophorectomy plus combination chemotherapy or immediate combination chemotherapy, and ER-negative patients were directly assigned to combination chemotherapy. Hence ER-negative patients need not have been healthy enough to be randomized to oophorectomy. With only 14% of the patients still alive, median survival on the three studies was 30, 24, and 28 months. The median survival of individual treatments changed noticeably in ECOG 2174 and ECOG 2177 with long-term follow-up. At this time there are no differences in survival between randomized regimens in any of the three trials. In a multivariate model, factors associated with significantly poorer survival were visceral-dominant disease, nodal metastases, breast metastases, age younger than 45 years, ER negativity, and not receiving chemotherapy immediately after oophorectomy. This treatment difference was thus not due to imbalances in the prognostic variables used in the model, but it may be due to imbalances of unknown prognostic factors or differences in patient selection.

Adult↗

PubMedDate not supplied

Ovine hourly fetal urine production: relation to fetal electrocortical activity.

OBJECTIVE: Ultrasound studies of hourly urine production rate in human fetuses have suggested that a fall in urine production occurs in state 2F (fetal quiet sleep) secondary to a state-dependent decrease in renal blood flow. We sought to ascertain the relationship between fetal hourly urine production rate and behavioral state in the near-term ovine fetus, a model in which urine production and fetal brain activity can be directly measured. METHODS: Six ewes with singleton pregnancies were prepared with vascular and amniotic fluid catheters. Fetuses were prepared with hindlimb vascular catheters, a bladder catheter, and biparietal ECoG electrodes. After at least 5 days of recovery (ga 130 +/- 2 days; term = 145-150 days), each animal was monitored for a 6-h period. Urine production was measured by draining the bladder catheter through a drop counter and fetal ECoG was continuously recorded (sampling rate of 50 Hz). ECoG activity was analyzed using power spectral analysis and periods of active and quiet sleep identified using both signal amplitude and corresponding 85% spectral edge frequency. RESULTS: Basal fetal arterial pH (7.36 +/- 0.01), pO2 (22.0 +/- 1.2 mmHg) and pCO2 (47.0 +/- 1.6 mmHg) and plasma (295 +/- 2 mOsm/kg) and urine (179 +/- 3 mOsm/kg) osmolalities were within normal ranges. Active and quiet sleep comprised 50 +/- 2 and 43 +/- 1% time, respectively. There was no difference in hourly urine production rate in active sleep (21.4 +/- 9.7 ml/h) and quiet sleep (18.8 +/- 7.7 ml/h). CONCLUSIONS: 1) Hourly fetal urine production rate is independent of ECoG activity state in the near-term ovine fetus. 2) Assuming only minor species differences, ultrasound measurement of human fetal hourly urine production rate can be performed without concern for fetal neurobehavioral state changes.

Animals↗

PubMed1982

Neurons in human epileptic cortex: correlation between unit and EEG activity.

A total of 90 neurons were recorded extracellularly from 17 awake patients undergoing craniotomy for excision of epileptogenic cortex. Relationships between single-unit activity and gross epileptiform spikes recorded locally by the microelectrode or from the immediate overlying cortical surface by electrocorticography (ECoG) were examined. Similar relationships were also sought between interictal bursts from nearby cells when action potentials from several neurons had been recorded simultaneously by the tungsten electrodes. Although 40 single units fired action potentials in some relation to ECoG spikes, the relationships were variable between units and, often, for the same unit. For many units, action potentials were more consistently related to one phase of the local field potential recorded through tungsten microelectrodes than to the ECoG recorded from the overlying cortical surface. Synchronous firing between single units recorded simultaneously by the same microelectrode was rarely seen except at the onset of an ictal event. In addition, a high degree of synchrony between unit firing and local ECoG spikes was recorded in a few patients, but these patients had frequent focal spontaneous seizures. The data imply that in human epilepsy, unlike some animal models of the disorder, relationships between surface epileptiform events and single-unit burst firing are not easily found in interictal recordings. The data also suggest that synchrony between unit and surface events requires a high degree of synchrony among neurons within the epileptogenic focus.

Electroencephalography↗

PubMed2004

Prognostic factors and long-term survivorship in patients with recurrent or metastatic carcinoma of the head and neck.

BACKGROUND: The current study was conducted to identify prognostic factors and report the characteristics of long-term survivors in patients with recurrent or metastatic carcinoma of the head and neck who were treated with cisplatin-based combination chemotherapy in two randomized, Phase III trials conducted by the Eastern Oncology Cooperative Group (ECOG) (E1393 and E1395). METHODS: The authors analyzed prognostic factors for response and survival by combining data from the E1393 trial, which compared cisplatin plus paclitaxel at two dose levels, with data from the E1395 trial, which compared cisplatin plus paclitaxel with cisplatin plus 5-fluorouracil (5-FU), using logistic regression and Cox regression models. RESULTS: A total of 399 eligible patients were included. The median follow-up was 4.7 years. The 1-year overall survival (OS) rate for all patients was 32%, the median OS was 7.8 months, and the objective response rate was 32%. On multivariate analysis, the following were found to be independent unfavorable predictors of objective response: weight loss of > 5%, an ECOG performance status of 1 (vs. 0), residual disease at the primary tumor site, a primary tumor site other than the oropharynx, prior radiation therapy (RT) (P = 0.056), and well/moderate tumor cell differentiation (P = 0.067). Independent unfavorable prognostic factors for OS were weight loss, an ECOG performance status of 1 (vs. 0), well/moderate tumor cell differentiation, a primary tumor in the oral cavity or hypopharynx, and prior RT. The following were found to be independent unfavorable prognostic factors for time to disease progression: well/moderate tumor cell differentiation, a oral cavity or hypopharyngeal primary tumor, and prior RT. Patients with < or = 2 adverse prognostic factors were reported to have a median OS of 1 year, whereas patients with 3-5 adverse prognostic factors were found to have a median OS of 0.5 years (P < 0.0001). Forty-nine patients (12%) survived for > or = 2 years and 6 patients were alive at 5 years. Two-year survivors were more likely to have achieved an objective response to chemotherapy, have poor tumor cell differentiation, be white, have an ECOG performance status of 0, and have received no prior RT. CONCLUSIONS: Clinical parameters and tumor cell differentiation appear to be strong pretreatment predictors of outcome in patients with carcinoma of the head and neck and should be considered in the design of future randomized trials. A small percentage of patients with recurrent head and neck carcinoma can achieve long-term survival.

Adult↗

PubMed1995

The relevance of interictal rCBF brain SPECT in temporal lobe epilepsy: diagnostical value and effects of spatial resolution.

Interictal rCBF-SPECT is frequently being used as an adjunctive method for localization of an epileptogenic area during presurgical evaluation of patients suffering from medically refractory temporal lobe epilepsy. This study retrospectively evaluates interictal rCBF-SPECT using Tc-99m-HMPAO in comparison to the results of MRI. The final results of surface EEG and ECoG and the postsurgical clinical results as to seizure frequency were used a a 'gold-standard' for the evaluation of both imaging procedures. As spatial resolution is discussed to be the major reason for higher sensitivity of F-18-DG-PET compared to rCBF-SPECT, special attention has been paid to the spatial resolution of the different SPECT systems being used in this study. In 55 patients the complete data set could be obtained retrospectively, 36 of them being evaluated using SPECT systems with relatively low spatial resolution (Picker Dyna 2000, Elscint Helix) and 19 pt. being evaluated using moderate- to high-resolution SPECT systems (ADAC Genesys, DSI Ceraspect). Overall sensitivity of the interictal rCBF-SPECT was 75%, with 69% for low-resolution systems and 84% for high-resolution systems. Approximately at the same time when our institution installed the ADAC Genesys, the MRI equipment was changed form the 1.5 T Philips Gyroscan S15 to the 1.5 T Philips Gyroscan ACS II, the latter allowing superior imaging opportunities. Overall sensitivity of MRI was 60%, with 56%, for the Gyroscan S15 and 68% for the Gyroscan ACS II. The overall positive predictive value (PPV) was 87% for the interictal rCBF-SPECT and 87% for the MRI. Due to the lack of true negative studies in this population specificity was not calculated. False lateralization using rCBF-SPECT occurred in 5 pts. (9%), however, in 3 pts. the area of hypoperfusion correlated with a detectable MRI pathology, yet EEG/ECoG revealed the epileptogenic focus to be elsewhere. In conclusion, the interictal rCBF-SPECT revealed reasonable sensitivity and PPV in pt. suffering from focal temporal lobe epilepsy and modern SPECT systems showed significantly improved results. Since there is a variety of possible reasons for regional cortical hypoperfusion, the interictal SPECT could add significant information prior to the application of ECoG. This specially appeared to be useful in patients with abnormal MRI scan. Furthermore, in patients presenting with a clear pathology on MRI and a corresponding EEG focus, ECoG could be avoided if the interictal rCBF-SPECT additionally showed localized and singular involvement of the affected temporal lobe. ECoG was mainly applied in those patients with relatively wide-spread hypoperfusion additionally involving frontal or parietal cortical areas.

Adolescent↗

PubMed2006

Prospective study of quality of life in adults with newly diagnosed high-grade gliomas.

OBJECTIVE: To assess baseline quality of life (QOL) and its prognostic importance for adults with newly diagnosed high-grade gliomas, we analyzed QOL and outcome data prospectively collected in three phase II high-grade glioma protocols. METHODS: At study entry, patients completed five self-administered forms to assess overall QOL (linear analogue scale assessment [LASA] and Functional Assessment of Cancer Therapy-Brain [FACT-Br]); fatigue (Symptom Distress Scale [SDS]); excessive daytime somnolence (Epworth Sleepiness Scale [ESS]); and depression (POMS-SF). Folstein Mini-Mental State Examination (MMSE) and Eastern Cooperative Oncology Group (ECOG) performance scores (PS) were obtained by the health care provider. RESULTS: Baseline QOL data were available for 194 of 220 patients (88%) enrolled in the three protocols. Differences in baseline QOL among the three studies were not statistically significant. One-third of patients had clinically significant fatigue at baseline. Increased fatigue (P = 0.003), excessive daytime somnolence (P = 0.01), and lower overall QOL scores (LASA, P = 0.001; FACT-Br, P = 0.0001) correlated with worse ECOG PS. No relation was found between QOL and corticosteroid or anticonvulsant therapy, extent of resection, tumor grade, or sex. Multivariate analyses found worse ECOG PS (PS 2, P = 0.007) associated with increased fatigue. Worse ECOG PS (PS 2, P = 0.002) was also associated with worse overall QOL (LASA). On multivariate analyses of survival, increased fatigue (P = 0.003) predicted poorer overall survival. CONCLUSIONS: Performance status is related to QOL in patients with newly diagnosed high-grade brain tumors. Increased fatigue is an independent predictor of overall survival. Interventional studies directed at improving QOL, especially fatigue, may have important benefits for these patients.

Adult↗

PubMed1978

Restraint in primate chair may cause unusual behaviour in baboons; electrocorticographic correlates and corrective effects of diazepam.

Whereas primates restrained in a chair may usually be considered 'normal', the behaviour of baboons in this position was considerably altered: their eyes were closed and they only slightly reacted to the approach of the experimenter (opening of the eyes), in contrast with their active behaviour when left free to move about in their cage. When the ECoG was recorded from certain cortical areas (particularly somatic area I), an unusual pattern developed during the restrained state: 'drowsiness rhythms', which typically appear in this area during transition from wakefulness to sleep, developed in long sustained sequences. Administration of diazepam, an anxiolytic drug, caused both the behaviour and the ECoG of the restrained animal to return to normal (i.e., attentive behaviour and ECoG characteristic of the true waking state). The prolonged drowsy-like ECoG and behaviour may therefore underline a reaction to the 'stress' conditions brought on by restraint.

Animals↗

PubMed1979

Local cerebral metabolism during enflurane anesthesia: identification of epileptogenic foci.

Electrocorticographic (ECoG) and depth recordings have previously demonstrated the epileptogenic nature of surgical concentrations of the volatile anesthetic enflurane. We contrasted ECoG activity with local cerebral glucose uptake [( 14C]2-deoxyglucose autoradiography) in 23 brain structures in order to identify the epileptogenic foci. Autoradiograms were obtained from sectioned rat brain following a 30 min period of steady-state anesthesia at 1, 1.5, or 2 MAC (minimum alveolar concentration) enflurane. Pseudo-epileptiform ECoGs were obtained at 1 MAC where bursts of slow waves and sharp waves were evoked by peripheral sensory stimulation. At 1.5 MAC, the ECoG displayed frank, spontaneous epileptiform activity with large amplitude spike-wave complexes; repetitive auditory stimulation occasionally precipitated grand-mal seizures. At 2 MAC, spike complexes were less frequent and could not be repetitively driven. At 1 MAC enflurane, regional cerebral metabolism was generally depressed approximately 14% from the awake controls. However, metabolism in the dentate gyrus of the hippocampus and other subcortical structures in the limbic brain was increased. At 1.5 MAC this dichotomy in local cerebral metabolic rate was maximal; we observed increased metabolism in the hippocampus, habenula, habenulo-interpeduncular tract and interpeduncular nucleus and pineal. Metabolism in all other structures was significantly depressed (P less than 0.05) compared to awake values. At 2 MAC, metabolism was decreased in all structures. We conclude that the low seizure threshold hippocampus and related structures associated with the limbic system and its pathways are the epileptogenic foci for seizures induced with enflurane in the rat. At 1.5 MAC, epileptiform activity spreads throughout the visceral brain when seizure threshold is at a minimum.

Anesthesia, General↗

PubMedDate not supplied

Evidence that behavioural and electrocortical sleep induced by guanfacine is due to stimulation of alpha 2-adrenoceptors.

The effects of guanfacine and other drugs acting at alpha 1- and alpha 2-adrenoceptors on behaviour, electrocortical activity and ECoG spectrum power were studied in chicks and rats. Guanfacine, given systematically in chicks, produced behavioural and electrocortical slow-wave sleep lasting 100-200 min, depending on the dose; these effects were prevented by yohimbine, a selective antagonist, at alpha 2-adrenoceptors and potentiated by prazosin, a selective antagonist, at alpha 1-adrenoceptors. Similar behavioural and electrocortical effects were obtained after systemic or intraventricular infusion of guanfacine in rats. In addition, a significant increase in total and in lower frequency band (0-4; 4-8 Hz) voltage power was observed. Behavioural and ECoG effects of guanfacine were prevented by phentolamine or yohimbine, whereas prazosin and propranolol were ineffective. Yohimbine itself, given systemically in chicks, produced behavioural stimulation, vocalization, increase in locomotor activity and ECoG desynchronization, with a significant fall in total and 0-3, 3-6, 6-9 and 9-12 Hz voltage power lasting approx. 3 h. Desipramine, an inhibitor of noradrenaline reuptake, produced in chicks behavioural and ECoG arousal, vocalization, pecking, escape responses and aggressive behaviour. In conclusion, the present experiments show that guanfacine sedative effects seem to be mediated predominantly via an activation of presynaptic alpha 2-adrenoceptors and suggest that arousal is due to stimulation of post-synaptic alpha 1-adrenoceptors.

Animals↗

PubMed1985

Quantitative electrocortical changes in the rat induced by phencyclidine and other stimulants.

An automated technique for the continuous analysis of different frequency bands of the electrocorticogram (ECoG) of the rat has been used to quantify the actions of phencyclidine (PCP) and various other stimulant drugs. It has been demonstrated that phencyclidine, etoxadrol and LY154045 produced similar changes in the individual frequency bands whereas amphetamine and apomorphine had different profiles of activity. The phencyclidine-like compounds exhibited extremely strong stimulation of the ECoG with very large increases recorded in high frequency (15-50 Hz) activity and reductions in all other frequency bands. Various compounds have been used in an attempt to antagonise the changes in the ECoG. Chlorpromazine caused a slight shift in the dose-response curves as did chlordiazepoxide when used with phencyclidine. The GABA agonists, THIP and muscimol, had no effect on the stimulation of the ECoG. In contrast another presumed GABA agonist, baclofen, proved to be the most effective agent for blocking the stimulation induced by phencyclidine. The role of the GABAB receptor in the action of phencyclidine is discussed.

Animals↗

PubMed1988

Behavioural and electrocortical changes induced by paraquat after injection in specific areas of the brain of the rat.

The behavioural and electrocortical effects of paraquat were studied after its administration into the substantia nigra, pars compacta, an area where dopamine-(DA) containing cell bodies are present, into the caudate nucleus, where DA-containing nerve endings of the DA nigro-striatal system project, into the locus coeruleus, an area containing noradrenaline cell-bodies and into the n. raphe dorsalis or into the n. raphe medianus, two nuclei containing serotonin (5-HT) cell bodies. The intraventricular administration of paraquat (10 and 50 micrograms) produced an intense pattern of behavioural stimulation and an increase in locomotor activity, circling and the wet-dog syndrome. This symptomatology was accompanied by desynchronization of the electrocorticogram (ECoG) and the appearance of bilateral high voltage epileptogenic spikes, culminating in clonic convulsions. The infusion of paraquat into the s. nigra produced contralateral head and neck deviation, behavioural and motor stimulation, these effects being observed also with smaller doses (1 and 5 micrograms), than those used intraventricularly. The ECoG activity was desynchronized and characterized by high voltage spike discharges. A similar behavioural, postural and ECoG pattern was also observed after infusion of paraquat into the caudate nucleus (10, 25 and 50 micrograms). In addition, paraquat, infused into the locus coeruleus or into the raphe nuclei (5 and 10 micrograms), produced circling, escape responses, jumping and clonic convulsions accompanied by ECoG desynchronization and epileptic phenomena. In conclusion, the present experiments showed that paraquat was able to produce central neurotoxicological effects which did not seem to be specific, at least for the doses used, for the DA nigro-striatal system.

Animals↗

PubMed1982

Arousal a prerequisite for suckling in the conscious rabbit?

Electrocorticographic activity (ECoG) was recorded from the frontal cortex of unanaesthetized, lactating rabbits, and analysed in relation to the suckling behaviour of the animals. Suckling lasted 2--5 minutes each day and was always associated with a desynchronized ECoG. Milk ejection was never seen during slow wave sleep. Mild sedation of the doe caused a dose-dependent block of milk yield but did not affect her willingness to suckle and the ECoG was desynchronized during nursing. In contrast to the rat, but similar to the pig, sleep is not a prerequisite for reflex milk ejection in the rabbit. Evidence presented implies that ECoG arousal may be important for this reflex in the rabbit.

Animals↗