General and electrophysiological toxic effects of manganese in rats following subacute administration in dissolved and nanoparticle form.

In an attempt to model occupational and environmental Mn exposures and their possible interaction, young male Wistar rats were exposed to Mn by oral administration in dissolved form (MnCl(2)·4H(2)O, 14.84 and 59.36 mg/kg b.w.) and by intratracheal application of MnO(2) nanoparticles (2.63 mg/kg b.w.). After 3 and 6 weeks oral, or 3 weeks oral plus 3 weeks intratracheal, exposure, general toxicological, and electrophysiological tests were done. Body weight gain was significantly reduced after 6 and 3 plus 3 weeks exposure, but the effect of the latter on the pace of weight gain was stronger. Organ weights signalized systemic stress and effect on lungs. Changes in evoked electrophysiological responses (cortical sensory evoked potential and nerve action potential) indicated that the 3 plus 3 weeks combined exposure caused equal or higher changes in the latency of these responses than 6 weeks of exposure, although the calculated summed Mn dose in the former case was lower. The results showed the importance of the physicochemical form of Mn in determining the toxic outcome, and suggested that neurofunctional markers of Mn action may indicate the human health effect better than conventional blood Mn measurement.

Support for population level tobacco control policies in Hungary.

BACKGROUND: Smoking is the leading, preventable risk factor for premature death and disability in Hungary. The objective of this paper was to assess the social acceptability of and the predictors of holding favourable attitudes toward tobacco control policies among the Hungarian population. METHODS: A self-administered questionnaire-based study was carried out among individuals aged 16-70 years. Logistic regression analysis was used to assess whether support for the ten tobacco control policies varies as a function of age, sex, educational level, and smoking status. RESULTS: The majority of the respondents supported the studied tobacco control measures. Over 90 percent of the sample supported: fines for retailers selling tobacco products to minors (92.3%), stricter enforcement of restrictions on selling tobacco products to minors (90.5%), and a ban on smoking in health care institutions (91.4%). The lowest levels of support were for bans on sponsorship by the tobacco industry (52.8%) and price increases on tobacco products (54.9%). For each measure, support was significantly lower among smokers than non-smokers. Age and education were significantly related to support for some but not all measures. CONCLUSIONS: Strong majorities of Hungarians support the enactment and enforcement of a wide range of tobacco control measures, a fact that was acknowledged by Parliament's passage of the 2011 Anti-Smoking Law. Advocacy efforts to encourage the acceptance of tobacco control policies should focus not only on smokers, but also on younger and less educated non-smokers.

Nervous system effects in rats on subacute exposure by lead-containing nanoparticles via the airways.

CONTEXT AND OBJECTIVE: Lead (Pb) is a heavy metal harmful for human health and environment. From leaded gasoline (still used in certain countries), and in Pb processing and reprocessing industries, airborne particles are emitted which can be inhaled. In such exposure, the size of particles entering the airways is crucial. The nervous system is a primary target for Pb, and consequences like occupational neuropathy and delayed mental development of children are well-known. The aim of this work was to investigate the neurotoxicity of Pb nanoparticles (NPs) applied into the airways of rats. METHODS: Nano-sized lead oxide particles (mean diameter ca. 20 nm) were suspended in distilled water and instilled into the trachea of adult male Wistar rats (in doses equivalent to 2 and 4 mg/kg Pb), 5 times a week for 3 and 6 weeks. At the end, open field motility was tested, then central and peripheral nervous activity was recorded in urethane anesthesia. RESULTS AND CONCLUSION: The treated rats' body weight gain was significantly lower than that of the controls from the 3rd week onwards, and the weight of their lungs was significantly increased. Horizontal motility increased while vertical motility decreased. Spontaneous cortical activity was shifted to higher frequencies. The somatosensory cortical evoked potential showed increased latency and decreased frequency-following ability, and similar alterations were seen in the tail nerve. Significant Pb deposition was measured in blood, brain, lung and liver samples of the treated rats. The experiments performed seem to constitute an adequate model of the human effects of inhaled Pb NPs.

Nervous system effects of dissolved and nanoparticulate cadmium in rats in subacute exposure.

Cadmium, a toxic heavy metal with various applications in technology, can affect people both by environmental (foodborne) and occupational (inhalation) exposure and can cause nervous system damage. To model this, rats were subacutely treated either with CdCl(2) solution per os (3.0 mg kg(-1) b.w.) or nanoparticulate CdO(2) (particle size ca 65 nm) by intratracheal instillation (0.04 mg kg(-1) b.w.) alone or in sequential combination. Nervous system effects were observed at different levels of function (open field behavior, cortical electrical activity, nerve action potential) and some general toxicological indicators were also measured. Three weeks of oral plus one week of intratracheal exposure caused significant reduction of body weight gain and open field motility. Lengthening of latency of sensory evoked potentials, observed in all treated rats, was also the most significant in the group receiving oral plus intratracheal treatment. Conduction velocity of the tail nerve was likewise decreased in all treated groups. Several of the effects pointed to a potentiating interaction between the two forms of Cd. Modeling environmental and occupational Cd exposure by oral and intratracheal application in rats was feasible, with results suggesting serious negative health effects in humans suffering such a combined exposure.

Diabetic Retinopathy Screening in Patients with Diabetes Using a Handheld Fundus Camera: The Experience from the South-Eastern Region in Hungary.

PURPOSE: Diabetic retinopathy (DR) is the leading cause of vision loss among active adults in industrialized countries. We aimed to investigate the prevalence of diabetes mellitus (DM), DR and its different grades, in patients with DM in the Csongrád County, South-Eastern region, Hungary. Furthermore, we aimed to detect the risk factors for developing DR and the diabetology/ophthalmology screening patterns and frequencies, as well as the effect of socioeconomic status- (SES-) related factors on the health and behavior of DM patients. METHODS: A cross-sectional study was conducted on adults (>18 years) involving handheld fundus camera screening (Smartscope Pro Optomed, Finland) and image assessment using the Spectra DR software (Health Intelligence, England). Self-completed questionnaires on self-perceived health status (SPHS) and health behavior, as well as visual acuity, HbA1c level, type of DM, and attendance at healthcare services were also recorded. RESULTS: 787 participants with fundus camera images and full self-administered questionnaires were included in the study; 46.2% of the images were unassessable. T1D and T2D were present in 13.5% and 86.5% of the participants, respectively. Among the T1D and T2D patients, 25.0% and 33.5% had DR, respectively. The SES showed significant proportion differences in the T1D group. Lower education was associated with a lower DR rate compared to non-DR (7.7% vs. 40.5%), while bad/very bad perceived financial status was associated with significantly higher DR proportion compared to non-DR (63.6% vs. 22.2%). Neither the SPHS nor the health behavior showed a significant relationship with the disease for both DM groups. Mild nonproliferative retinopathy without maculopathy (R1M0) was detected in 6% and 23% of the T1D and T2D patients having DR, respectively; R1 with maculopathy (R1M1) was present in 82% and 66% of the T1D and T2D groups, respectively. Both moderate nonproliferative retinopathy with maculopathy (R2M1) and active proliferative retinopathy with maculopathy (R3M1) were detected in 6% and 7% of the T1D and T2D patients having DR, respectively. The level of HbA1c affected the attendance at the diabetology screening (HbA1c > 7% associated with >50% of all quarter-yearly attendance in DM patients, and with 10% of the diabetology screening nonattendance). CONCLUSION: The prevalence of DM and DR in the studied population in Hungary followed the country trend, with a slightly higher sight-threatening DR than the previously reported national average. SES appears to affect the DR rate, in particular, for T1D. Although DR screening using handheld cameras seems to be simple and dynamic, much training and experience, as well as overcoming the issue of decreased optic clarity is needed to achieve a proper level of image assessability, and in particular, for use in future telemedicine or artificial intelligence screening programs.

Determinants of health-promoting lifestyle behaviour in the rural areas of Hungary.

Today chronic non-communicable diseases are the major cause of death and disability worldwide. Chronic diseases are determined by common risk factors (e.g. smoking). The purpose of this study was to develop a health-promoting behaviour index, and to evaluate the impact of the social and the demographic characteristics of the individuals, self-rated health and certain features of settlements on the score of this index. A population-based, cross-sectional health survey was conducted. Altogether 91 settlements with various sizes of population, and at various stages of social, economic and infrastructural development took part in the survey. The survey was based on interviewer-administered questionnaires, 3380 subjects filled in the questionnaires correctly, and the response rate was 82.4%. Questions on lifestyle factors referred to smoking, nutritional habits and physical activity. Low level (5.5%) of people have achieved the 'complete' health-promoting behaviour, including non-smoking, healthy nutrition and physical activity. There were significant associations between health-promoting behaviour and demographic, social and economic characteristics of the individuals and their dwelling place. The lower prevalence of healthy lifestyle activities among lower educated, lower income and aged people living in small settlements call the attention to the higher risk of these people. On planning interventions, special attention should be paid to the geographically, infrastructurally, socially and demographically disadvantaged population groups to provide equal opportunities for them, to live a healthy way of life. The application of the health-promoting index might be used to monitor the effects of interventions to alter lifestyle at community level.

Psychosocial Work Environment Risk Factors Among University Employees - A Cross-sectional Study in Hungary.

INTRODUCTION: National and international research results have highlighted the fact that workplace stress causes mental and somatic problems. The aim of the present paper is to define exposure to workplace-related risk factors, with special focus on psychosocial risk factors, and the way they interconnect with workplace conditions, relationships with superiors and colleagues, and moral, professional and financial appreciation. METHODS: Cross-sectional research with the help of an anonymous online self-administered questionnaire was carried out among 261 higher education employees (67% women, 33% men, mean age 43.4 years) from 12 faculties of the University of Szeged, Hungary. Statistical analysis was performed using IBM SPSS 22.0. RESULTS: The primary workplace stress factors for university employees were strict deadlines (80.4%), frequent overwork (64.2%) and difficulty in meeting requirements (56.7%). Communication problems with colleagues and superiors were also highlighted (47.5%). Job strain was higher for women than for men. With regard to low financial, professional, and moral appreciation, employees were characterised by the existence of work requirements impossible to meet, as well as by low autonomy. Experience of anxiety and aggression came along with low financial and moral appreciation (p<0.001). CONCLUSIONS: Our data suggests that employees at the university were subject to several psychosocial risk factors, and worked under considerable mental stress, leading to a higher prevalence of mental health problems. The results highlight the need for a health-focused policy-making in higher education to reduce health expenditure and increase efficiency at work.

The synaptic and nonsynaptic glycine transporter type-1 inhibitors Org-24461 and NFPS alter single neuron firing rate in the rat dorsal raphe nucleus. Further evidence for a glutamatergic-serotonergic interaction and its role in antipsychotic action.

Single neuron firing rate was recorded from dorsal raphe nucleus of anesthetized rats. The firing rate of raphe neurons varied from 4 to 8 discharge per second before drug administration and this neuronal activity was decreased by L-701,324 (2 mg/kg i.v. injection), a competitive antagonist of glycineB binding site of N-methyl-D-aspartate (NMDA) receptors. The glycine transporter type-1 (GlyT1) antagonists Org-24461 (10 mg/kg i.v.) and NFPS (3 mg/kg i.v.) reversed the inhibitory effect of L-701,324 on single neuron activity recorded from dorsal raphe nucleus of the rat. Org-24461 and NFPS both tended to increase the raphe neuronal firing rate also when given alone but their effect was not significant. This finding serves further evidence that glutamate released from axon terminals of the cortico-striatal projection neurons stimulates serotonergic neurons in the raphe nuclei and this effect is mediated at least in part by postsynaptic NMDA receptors. Thus, GlyT1 inhibitors are able to reverse the hypofunctional state of NMDA receptors, suggesting that these drugs may have beneficial therapeutic effects in neurological and psychiatric disorders characterized with impaired NMDA receptor-mediated transmission.

[Applicability of the abbreviated version of the World Health Organization's quality of life questionnaire in Hungary]. / Az Egészségügyi Világszervezet rövidített életminoség kérdoívének hazai alkalmazhatóságáról.

INTRODUCTION: Quality of life, as a subjective parameter of the general condition, is suitable for characterization of the health status of populations or patient groups, and for studying the effects of therapeutic or preventive interventions. AIMS: To test the applicability and reliability in Hungary of the abbreviated form of the quality of life questionnaire developed by WHO, one of several ways to measure the quality of life. METHODS: Questionnaire-based cross-sectional investigation was performed among altogether 814 persons, in small settlements of population under 1000 and 2000, and in a small town for control, in Csongrád county, Hungary. The reliability and validity of the quality of life questionnaire was tested, within each group of questions, by means of Cronbach's alpha, ANOVA and Kruskal-Wallis tests, and by Spearman's rho correlation coefficient. RESULTS: The mean values of the four domains of quality of life - physical, psychological, social and environmental - showed no noteworthy differences. The Cronbach's alpha figures of the internal consistency test on separate groups of questions and on all questions were in all cases above the expected minimum of 0.7. The means calculated for each domain of quality of life were decreasing with increasing age. Healthy people estimated each aspect of quality of life as significantly better, compared to the sick. Correlation tests showed that all dimensions of the quality of life were in close positive correlation with the general quality of life, with the level of satisfaction with the own health, with the self-assessed health, and with the responses given on other questions related to the social or health situation of the questioned. CONCLUSION: The variation of the questionnaire, adapted to Hungarian conditions, proved to be suitable for testing the quality of life of persons with various demographical, social and health conditions, and for distinction between the healthy and the sick. The sheet, which can be filled in quickly and easily, enables the measurement of quality of life in the Hungarian population, and the comparison of that with international data.

Alterations in the cortical and peripheral somatosensory evoked activity of rats treated with 3-nitropropionic acid.

In this study, the action of 3-nitropropionic acid (3-NP) on the parameters of the cortical and peripheral evoked potentials was investigated in rats in different administration schemes (20 mg/kg i.p. during recording or 24 h before, and 5x 15 mg/kg daily 28 days before recording) to elucidate some neurophysiological effects of the substance. Responses in the somatosensory cortex and in the tail nerve, evoked by peripheral electric stimulation, were recorded in acute preparation under urethane anaesthesia. Amplitude, latency, and duration of the responses were measured. In rats treated 28 days before recording, latency of the cortical response was significantly (and the duration slightly) increased by 3-NP. The frequency dependence of the tail nerve response was more pronounced than that of the cortical response. After acute administration of 3-NP, the amplitude of the somatosensory evoked potential decreased. With double stimuli, the ratio of the amplitudes of the two responses (relative fatigue) was treatment-dependent. The relative refractory period of the tail nerve was altered both by acute and subacute 3-NP treatment. These results may be relevant in 3-NP based disease models but it needs further studies to find possible connections between the known biochemical effects of 3-NP and the functional neurotoxical changes described. The mode of evoked response analysis used is, theoretically, applicable for other neurotoxic effects and can be the base of development of functional biomarkers.

Diabetic Retinopathy Screening Using Telemedicine Tools: Pilot Study in Hungary.

Introduction. Diabetic retinopathy (DR) is a sight-threatening complication of diabetes. Telemedicine tools can prevent blindness. We aimed to investigate the patients' satisfaction when using such tools (fundus camera examination) and the effect of demographic and socioeconomic factors on participation in screening. Methods. Pilot study involving fundus camera screening and self-administered questionnaire on participants' experience during fundus examination (comfort, reliability, and future interest in participation), as well as demographic and socioeconomic factors was performed on 89 patients with known diabetes in Csongrád County, a southeastern region of Hungary. Results. Thirty percent of the patients had never participated in any ophthalmological screening, while 25.7% had DR of some grade based upon a standard fundus camera examination and UK-based DR grading protocol (Spectra™ software). Large majority of the patients were satisfied with the screening and found it reliable and acceptable to undertake examination under pupil dilation; 67.3% were willing to undergo nonmydriatic fundus camera examination again. There was a statistically significant relationship between economic activity, education and marital status, and future interest in participation. Discussion. Participants found digital retinal screening to be reliable and satisfactory. Telemedicine can be a strong tool, supporting eye care professionals and allowing for faster and more comfortable DR screening.

Effect of folic acid supplementation on aluminum accumulation in rats.

OBJECTIVE: Exposure to many xenobiotics may cause depletion of folic acid (folate), which is an essential vitamin for humans. Replacement of folate can be effective in protection against some diseases and in partial or total prevention of adverse effects related to xenobiotics. Aluminum (Al) is the most widely distributed metal in the outer crust of the earth. Its toxicity in humans is well known. However, there is no evidence that folate can decrease accumulation of Al to which humans can be exposed in many ways. The aim of the present study was to quantify organ Al accumulation and to evaluate whether there is any protective (or reductive) effect of folic acid on Al accumulation. METHODS: Male Wistar rats were assigned oral Al chloride (200 mg x kg(-1) x d(-1), n = 10, group 1) alone or in combination with folic acid (20 mg x kg(-1) x d(-1), n = 10, group 2) for 8 wk. At the end of the period, bone, kidney, brain, and blood samples were collected, and Al concentrations were determined by electrothermal atomic absorption spectrophotometry. RESULTS: Mean values of Al in the tissue samples from group 1 were higher than those from group 2 (all P < 0.05). No difference was observed in serum Al levels between groups (P > 0.05). CONCLUSION: These results suggest that folate supplementation might be useful to decrease Al accumulation in its main target organs, i.e., bone, kidney, and brain.

Subchronic mercury treatment of rats in different phases of ontogenesis: functional effects on the central and peripheral nervous system.

Electrophysiological changes caused by inorganic mercury administration during the pre- and/or postnatal development were studied. Pregnant female Wistar rats were treated, by gavage, with 0.4, 0.8 or 1.6 mg/kg mercury (HgCl2 diluted in distilled water): 1/ from day 5 to 15 during pregnancy (P protocol); 2/ from day 5 to 15 of pregnancy+for 4 weeks of lactation (P+L protocol); 3/ from day 5 to 15 of pregnancy+for 4 weeks of lactation, and the offspring were further treated for 8 weeks post-weaning (P+L+P protocol). Electrophysiological parameters (electrocorticogram, cortical evoked potentials, conduction velocity and refractory periods of peripheral nerve) of the male offspring from dams in the groups treated according to the above protocols were investigated at the age of 12 weeks. The rats' spontaneous and evoked electrophysiological activity underwent dose- and treatment-dependent changes following the treatment (increased frequency of spontaneous activity, lengthened latencies and duration of evoked potentials, lower conduction velocity of the peripheral nerve, etc.). In the same rats, however, the treatment failed to cause major signs of general intoxication. The results emphasize the functional neurotoxic risk arising from the continuous presence of inorganic mercury in the human environment, and point to possible use of early functional changes for monitoring the effects of mercury.

Functional neurotoxic effects in rats elicited by 3-nitropropionic acid in acute and subacute administration.

Changes possibly induced by 3-NP in electrophysiological functional characteristics of the central nervous system are, in contrast to biochemical and morphological alterations, less well known. In this study, the usability of a standard neurophysiological investigation system to detect functional changes caused by 3-NP administration in rats was studied. In subacute treatment, 10 or 15mg/kg 3-NP was given i.p. on five consecutive days to groups of 10 rats and the effects were checked 4 weeks later. Acutely treated rats received 20mg/kg i.p. after several control records. For recording, the animals' left hemisphere was exposed in urethane anesthesia. Silver electrodes were placed on the cortical sensory foci and tungsten needles in the subcortical (caudatum, globus pallidus) recording sites. Spontaneous electrical activity, as well as somatosensory, visual and auditory evoked potentials, were recorded. Following subacute treatment, the slowest (theta) and fastest (beta2 and gamma) frequencies of the spontaneous activity were changed, differently in the cortical versus subcortical sites. In the sensory evoked potentials after subacute treatment, an increase of the latency was seen in all sensory areas. In the acutely treated animals, the amplitude of the somatosensory evoked potential decreased after giving 3-NP. With double stimuli, the relation of the two responses was treatment- and interval-dependent. Understanding the mechanism of these effects may widen the knowledge base for using 3-NP in disease models.

Effect of acute administration of certain heavy metals and their combinations on the spontaneous and evoked cortical activity in rats.

The aim of this study was to see the effect of acutely administered inorganic lead, mercury, manganese, and their combinations, on the electrical activity in the somatosensory system of rats. Male Wistar rats were anaesthetised with urethane, the head was fixed in a stereotaxic frame and the left hemisphere was exposed. Weak electric shocks to the whiskers and the tail served as stimuli. Spontaneous and stimulus-evoked activity was recorded from the primary projection area of the whiskers and the tail. After an hour of control recording, one of the following was given to the rat i.p.: 1000mg/kg Pb(2+), 7mg/kg Hg(2+), 50mg/kg Mn(2+), 500mg/kg Pb(2+)+25mg/kg Mn(2+), or 500mg/kg Pb(2+)+3.5mg/kg Hg(2+). Lead caused a massive increase in the cortical response amplitude, starting immediately after administration and developing in the next 40-50min. Latency showed a minimal increase. The spontaneous activity was moderately shifted to lower frequencies. The effect of Hg(2+) on the response amplitude and on the ECoG was similar but stronger than that of Pb(2+). The effect of Mn(2+) on the evoked activity was marked but less strong than with Pb(2+). The ECoG shift was moderate. With Hg(2+) and Mn(2+), the response amplitude showed first a decrease than an increase. The effect of the Pb(2+)+Mn(2+) combination on the activities was not additive but the correlation between the alteration of the ECoG and the evoked potential was stronger than with any of the metals alone. With Pb(2+)+Hg(2+), the effect of Pb(2+) dominated on the evoked and that of Hg(2+) on the spontaneous activity. In the peripheral nerve, action potential amplitude and conduction velocity were decreased. These alterations of the spontaneous and stimulus-evoked cortical activity probably reflected a specific action of the heavy metals on the nervous activity.

Behavioral and neurotoxic effects seen during and after subchronic exposure of rats to organic mercury.

Young adult male Wistar rats (24/group) were treated for 5 weeks with methyl mercury(II)chloride (corresponding to 0.5 and 2.0mgHg°/kg b.w., control: distilled water) by gavage, followed by a 19 weeks post-treatment period. Spontaneous motility, psychomotor performance and sensorimotor gating was repeatedly tested, electrophysiological recordings done, in the rats throughout the whole experiment. Decreased horizontal open field activity, reduced number of "noise positive" startle responses, as well as increase of startle response onset latency and peak time, and decrease of peak amplitude, was seen in the treated animals. Most changes disappeared in the post-treatment period. In the spontaneous cortical and hippocampal activity, altered distribution of the frequency bands was seen after 5 weeks of treatment but not at the end of the post-treatment period. Hippocampal population spikes in the treated animals were depressed and showed less potentiation, which effect was still present 19 weeks after finishing the treatment. The duration of the sensory cortical evoked potentials was shorter than in the controls. In the treated rats, tyrosine hydroxylase-immunoreactive boutons in the substantia nigra pars reticulata were shrunk; blood and brain Hg levels were significantly higher and decreased only slowly. Considering the continuous presence of low levels of mercurials in the human environment, effects of this kind may be supposed as the background of some human neurobehavioral abnormalities.

Behavioral and neurotoxicological effects of subchronic manganese exposure in rats.

In male Wistar rats, behavioral and electrophysiological investigations, and blood and brain manganese level determinations, were performed; during 10 weeks treatment with low-dose manganese chloride and a 12 weeks post-treatment period. Three groups of 16 animals each received daily doses of 14.84 and 59.36mg/kg b.w. MnCl(2) (control: distilled water) via gavage. During treatment period, Mn accumulation was seen first in the blood, then in the brain samples of the high-dose animals. Short- and long-term spatial memory performance of the treated animals decreased, spontaneous open field activity (OF) was reduced. The number of acoustic startle responses (ASR), and the pre-pulse inhibition (PPI) of these, diminished. In the cortical and hippocampal spontaneous activity, power spectrum was shifted to higher frequencies. The latency of the sensory evoked potentials increased, and their duration, decreased. By the end of the post-treatment period, Mn levels returned to the control in all samples. The impairment of long-term spatial memory remained, as did the number of acoustic startle responses. Pre-pulse inhibition, however, returned to the pre-treatment levels. The changes of the open field activity disappeared but a residual effect could be revealed by administration of d-amphetamine. The electrophysiological effects were partially reversed. By applying a complex set of methods, it was possible to obtain new data for a better-based relationship between the known effects of Mn at neuronal level and the behavioral and electrophysiological outcomes of Mn exposure.

Combined effects of subchronic exposure to lead, mercury and alcohol on the spontaneous and evoked cortical activity in rats.

The aim of this study was to investigate the effects of a combination of well-known neurotoxic heavy metals, lead and mercury, with ethanol. For 12 weeks, young adult male Wistar rats were given plain tap water or water containing 5% (v/v) ethanol to drink, and were treated with two doses of lead acetate or mercuric chloride by gavage. Accordingly, there was a water-drinking and an alcohol-drinking control group. After the treatment period, spontaneous and stimulus-evoked activity from the somatosensory, visual and auditory cortical areas was recorded. The frequency spectrum of the spontaneous activity, as well as latency and duration of the evoked potential were analysed. A shift in frequency was observed in the electrocorticogram, and lengthened latency and duration times in the evoked potentials. Alcohol seemed to influence the effect of the metals. Combined exposure to heavy metals and regular alcohol consumption may result in more severe central and/or peripheral neurotoxic outcomes.

Changes in the central nervous activity of rats treated with dimethoate in combination with other neurotoxicants in different phases of ontogenesis.

Organophosphates are usually found in the environment with other pesticides and with pollutants of industrial origin can cause combined exposure involving unknown interactions between the agents. In this study, female Wistar rats were given 1/25 LD50 of dimethoate by gavage, combined with the same LD50 fractions of propoxur and cypermethrin or with arsenic (6.66 mg kg(-1)). The doses were given from day 5 to 15 of pregnancy, or that plus for the 4 weeks of lactation, or that plus 8 weeks for the male offspring after weaning. Control rats received distilled water. Electrophysiological recording was done when the male offspring reached 12 weeks of age. Spontaneous activity and evoked potentials from the somatosensory, visual and auditory cortex; and conduction velocity and absolute and relative refractory periods of the tail nerve were measured. The general trend was a shift of the spontaneous cortical activity to higher frequencies and increase in the evoked potential latency. The results showed that combined exposure to several environmental toxicants could be more harmful than the effects of each substance alone, indicating the importance of combination toxicology in modelling human effects. Furthermore, these results emphasize the importance of avoiding toxic exposures in pregnant and nursing women.

Effects of 3-nitropropionic acid in rats: general toxicity and functional neurotoxicity.

3-Nitropropionic acid (3-NP) causes biochemical and morphological alterations in human and animal brain. Young adult male Wistar rats received 3-NP i. p. on five consecutive days and were investigated four weeks later (subacute treatment). Acute effects were investigated 24 h after one i. p. dose. Spontaneous or stimulus-evoked activity was recorded from cortical sensory foci, from subcortical nuclei and from the tail nerve, in urethane anesthesia. The subacutely treated rats were dissected and organ weights measured to study general toxic effects. After subacute treatment, decrease was seen in the theta, and increase in the beta-2 and gamma, band of the spontaneous activity, dissimilarly in the cortical vs. subcortical sites. Latency of the sensory evoked potentials increased in all sensory foci after subacute treatment. Following acute treatment, amplitude of the somatosensory evoked potential decreased. The weight of the thymus decreased significantly in the treated rats. Further studies could elucidate the link between biochemical effects of 3-NP and the observed functional neurotoxic changes.