Exposure to a 900 MHz electromagnetic field induces a response of the honey bee organism on the level of enzyme activity and the expression of stress-related genes

There are many artificial sources of radiofrequency electromagnetic field (RF-EMF) in the environment, with a value between 100 MHz and 6 GHz. The most frequently used signal is with a frequency of around 900 MHz. The direction of these changes positively impacts the quality of life, enabling easy communication from almost anywhere in the world. All living organisms in the world feel the effects of the electromagnetic field on them. The observations regarding the influence of a RF-EMF on honey bees, describing the general impact of RF-EMF on the colony and/or behavior of individual bees, such as reduction in the number of individuals in colonies, extended homing flight duration, decrease in breeding efficiency, changes in flight direction (movement of bees toward the areas affected by RF-EMF), increase in the intensity and frequency of sounds characteristic for those announcing the impending danger. In this work, we describe the changes in the levels of some of the stress-related markers in honey bees exposed to varying intensities and duration of RF-EMF. One-day-old honeybee worker bees were used for the study. The bees were randomly assigned to 9 experimental groups which were exposed to the following 900 MHz EMF intensities: 12 V/m, 28 V/m, and 61 V/m for 15 min, 1 h and 3 h. The control group was not exposed to the RF-EMF. Each experimental group consisted of 10 cages in which were 100 bees. Then, hemolymph was collected from the bees, in which the activity was assessed AST, ALT, ALP, GGTP, and level of nonenzymatic antioxidants albumin, creatinine, uric acid, and urea. Bees were also collected for the analysis of rps5, ppo, hsp10, hsp70, hsp90, and vitellogenin gene expression. Our study shows that exposure to a 900 MHz electromagnetic field induces a response in the honey bees that can be detected in the level of enzyme activity and the expression of stress-related genes. The response is similar to the one previously described as a result of exposition to UVB irradiation and most likely cannot be attributed to increased temperature.

Exposure to Magnetic Fields Changes the Behavioral Pattern in Honeybees (Apis mellifera L.) under Laboratory Conditions

Simple Summary

Electrically powered devices and power lines generate electromagnetic fields. Technological development has resulted in environmental pollution with anthropogenic electromagnetic fields. One of its components is the magnetic field. Its impact on living organisms is still under investigation, but there are reports suggesting that the direction of change is negative. Pollinators are very important for the environment and are also exposed to this factor. In this study, we wanted to investigate the impact of magnetic field exposure on the behavior of one of the key pollinators: the honeybee. The frequency of the tested field corresponded to those present under high voltage lines, as honeybees often forage in these areas. The results showed that the magnetic field caused a distribution in behavioral patterns, which may have a direct impact on foraging efficiency and pollination success.

Abstract

Earth’s magnetic field (MF) plays an important role for many species, including the honeybee, in navigation. Nowadays, much larger alternating fields are emitted by miscellaneous electric infrastructure components, such as transformers and power lines, and the environment is therefore polluted by an anthropogenic electromagnetic field, though little is known regarding its impact on living organisms. The behavior of animals is the first and easiest way to establish the impact of stress. It shows if the animal can detect the exposure and react to it. To investigate this, one-day-old bees were exposed to a 50 Hz magnetic field of induction at 1 mT and 1.7 mT for 10 min, 1 h, and 3 h under laboratory conditions. All groups exposed to the magnetic field showed differences in behavioral patterns. What is more, they presented a behavior absent in the control: loss of balance. There were differences, both in the ratio of behaviors and in the number of bouts—exposed bees more often changed behavior. Occurrence of differences is an indication of the reaction of the honeybee organism to the magnetic field. Loss of balance is a disturbing symptom, and behavior changes indicate a disturbance of the honeybee by the electromagnetic field.

Honey Bee Proteolytic System and Behavior Parameters under the Influence of an Electric Field at 50 Hz and Variable Intensities for a Long Exposure Time

Simple Summary

The amount of electromagnetic field (EMF) in the environment emitted by electrical and electronic devices, mobile phone masts, or power lines is constantly increasing. Honey bee can be exposed to the EMF in the environment, ^and the influence of this factor on bees is still under consideration. Studying the impact of EMF on honey bees can give valuable information about whether it poses a threat to them. The honey bee is an important pollinator, playing a significant role in maintaining biodiversity and food production. Our research showed that a 50 Hz electric field at various intensities reduced the number of occurrences of walking, contacts between individuals, and self-grooming, and increased the activity of proteases, which are involved in the immune system response.

Abstract

The effect of an artificial electromagnetic field on organisms is a subject of extensive public debate and growing numbers of studies. Our study aimed to show the effect of an electromagnetic field at 50 Hz and variable intensities on honey bee proteolytic systems and behavior parameters after 12 h of exposure. Newly emerged worker bees were put into cages and exposed to a 50 Hz E-field with an intensity of 5.0 kV/m, 11.5 kV/m, 23.0 kV/m, or 34.5 kV/m. After 12 h of exposure, hemolymph samples were taken for protease analysis, and the bees were recorded for behavioral analysis. Six behaviors were chosen for observation: walking, flying, self-grooming, contact between individuals, stillness, and wing movement. Bees in the control group demonstrated the highest number of all behavior occurrences, except flying, and had the lowest protease activity. Bees in the experimental groups showed a lower number of occurrences of walking, self-grooming, and contacts between individuals than the control bees and had significantly higher protease activity than the control bees (except that of alkaline proteases in the 23.0 kV/m group).

Changes in Honeybee Behavior Parameters under the Influence of the E-Field at 50 Hz and Variable Intensity

EM-fields come from both natural and anthropogenic sources. This study aimed to investigate changes in honeybee behavior parameters under the influence of an electric field at 50 Hz and variable intensity. Bees were exposed for 1 h, 3 h, or 6 h to the following artificial E-field intensities: 5.0 kV/m, 11.5 kV/m, 23.0 kV/m, or 34.5 kV/m. Bees in the control group were under the influence of an E-field <2.0 kV/m. Six basic behaviors were selected for bee observation (walking, grooming, flight, stillness, contact between individuals, and wing movement). Our research shows the impact of bee exposure time on behavioral change within groups. Exposure for 3 h caused a decrease in the time that bees spent on behaviors and in the number of occurrences. After 6 h, the parameters increased within the groups, as was the case with 1 h exposure. This may indicate that there is a behavioral barrier that allows the pattern to normalize for some time.

Changes in the Honeybee Antioxidant System after 12 h of Exposure to Electromagnetic Field Frequency of 50 Hz and Variable Intensity

Simple Summary

The honeybee is one of the most important links in the food production chain. In the environment of bee life, there are many threats that they have to face. Among them, we can distinguish pesticides, climate change, and predators. The intensive development of technology resulted in filling the natural environment with E-field of various frequencies and intensities. The study investigated the effect of the E-field with a frequency of 50 Hz at various intensities on the antioxidant system of the honeybee. The exposure of the bees lasted 12 h. The activity of the antioxidant system was investigated in hemolymph collected from young bees. Research has been undertaken in this direction because research by other authors has taken years to stimulate this system through the E-field. The superoxide dismutase (SOD), Catalase (CAT), and total antioxidant potential (FRAP) activity as major antioxidant enzymes were characterized. Research showed changes in the activity of SOD, CAT, and FRAP in all tested groups compared to the control group. The study of E-field appearing in the life of a honeybee enables an understanding of the impact of this factor on its functioning because food production depends on the integrity of this pollinator.

Abstract

In recent years, on a global scale, more and more reports of a phenomenon called CCD (Colony Collapse Disorder) have been reported. In addition to pesticides, diseases, and other environmental stressors, electromagnetic fields are also mentioned as one of the possible causes of CCD. One of the body’s first lines of defense against harmful factors is the antioxidant system. We hypothesized that electromagnetic field upregulate the activity of SOD (superoxide dismutase), CAT (catalases), and changed FRAP (total antioxidant potential) in honeybee hemolymph. In our research, 12 h bee’s exposure to E-field was analyzed to determine changes in the antioxidant system. The frequency of 50 Hz and various intensities were used: 5.0 kV/m, 11.5 kV/m, 23.0 kV/m, and 34.5 kV/m. Superoxide dismutase was characterized by four times higher activity in the study groups as compared to the control group. Catalase activity in all groups was characterized by statistically significantly different activity between the groups. The highest activity was recorded in the 34.5 kV/m group. The lowest activity was recorded in the 11.5 kV/m group. A relationship was found between different E-field intensities and changes in the antioxidant system.

[Conditionings of population exposure to electromagnetic fields associated with the rational use of 5G radiocommunication networks in Poland]

In 2017, preparations were made in Poland to provide all citizens with access to the Internet at a speed of at least 30 Mb/s, and at a speed of at least 100 Mb/s for 50% of households. This goal is to be realized, among others, by means of the fifth generation (5G) radio-communication networks. This work presents the assumptions of the 5G network structure and estimates of the level of population exposure toelectromagnetic fields related to their rational use. It was also analyzed whether, from the technical point of view, 5G networks could be implemented while respecting the currently acceptable level of electromagnetic field intensity in Poland (7 V/m), taking into account the current environmental exposure caused by antennas of cellular base stations. This is a contribution to the ongoing discussion on the need to change the requirements in Poland in order to limit the level of population exposure to electromagnetic fields. Based on the available documentation of the proposed technical standards, the theoretical analysis of environmental exposure to the electromagnetic field emitted by 5G systems shows that, with rational power management, obtaining the expected (compatible with 5G standards) quality of connections via base stations installed outside of buildings and using intelligent antenna systems with controlled beams, it will be possible to maintain the electric field strength and power density below the current limit values in places accessible to the public (<7 V/m, <0.1 W/m²). Med Pr. 2020;71(2):245-53.

[Protection of the population health from electromagnetic hazards - challenges resulting from the implementation of the 5G network planned in Poland]

There is an ongoing discussion about electromagnetic hazards in the context of the new wireless communication technology - the fifth generation (5G) standard. Concerns about safety and health hazards resulting from the influence of the electromagnetic field (EMF) emitted by the designed 5G antennas have been raised. In Poland, the level of the population's exposure to EMF is limited to 7 V/m for frequencies above 300 MHz. This limitation results from taking into account the protective measures related not only to direct thermal hazards, but also to diversified indirect and long-term threats. Many countries have not established legal requirements in this frequency range, or they have introduced regulations based on recommendations regarding protection against direct thermal risks only (Council Recommendation 1999/519/EC). For such protection, the permissible levels of electric field intensity are 20-60 V/m (depending on the frequency). This work has been created through an interdisciplinary collaboration of engineers, biologists and doctors, who have been for many years professionally dealing with the protection of the biosphere against the negative effects of EMF. It presents the state of knowledge on the biological and health effects of the EMF emitted by mobile phone devices (including millimeter waves which are planned to be used in the 5G network). A comparison of the EU recommendations and the provisions on public protection being in force in Poland was made against this background. The results of research conducted to date on the biological effects of the EMF radiofrequency emitted by mobile telecommunication devices, operating with the frequencies up to 6 GHz, do not allow drawing any firm conclusions; however, the research evidence is strong enough for the World Health Organization to classify EMF as an environmental factor potentially carcinogenic to humans. At the moment, there is a shortage of adequate scientific data to assess the health effects of exposure to electromagnetic millimeter waves, which are planned to be used in the designed 5G devices. Nevertheless, due to the fact that there are data indicating the existence of biophysical mechanisms of the EMF influence that may lead to adverse health effects, it seems necessary to use the precautionary principle and the ALARA principle when creating environmental requirements for the construction and exploitation of the infrastructure of the planned 5G system. Med Pr. 2020;71(1):105-13.

[Electromagnetic field in the environment - estimation methods and monitoring]

BACKGROUND

The paper describes the current legal status related to electromagnetic field (EMF) measurements in the context of environmental protection. It also presents the assumptions and exemplary results obtained from the EMF National Monitoring System which, in the authors' opinion, could be more reliable and better adapted to the current state of affairs in the radiocommunication industry.

MATERIAL AND METHODS

A simplified method of estimating electromagnetic field intensity from various sources, including in particular cellular base stations, using their basic parameters, was described. The electromagnetic field monitoring system operating in Poland was described, and alternative monitoring methods were presented. The authors introduced their own concept of mobile monitoring, whose assumptions perfectly fit into the current realities and can be performed with the use of the current measurement equipment available to laboratories of the Voivodeship Inspectorates for Environmental Protection.

RESULTS

The construction of the measurement system was presented, and its measurement verification was carried out. Measurement errors resulting from the use of weather-resistant casing and from placing the device on the roof of the vehicle were estimated, confirming that their impact on the measurement uncertainty budget tends to be negligible. Auxiliary software for mobile monitoring was presented, with the aid of which verification was made by carrying out monitoring measurements in the city of Wrocław.

CONCLUSIONS

The results obtained during the monitoring measurements in real conditions confirmed that the proposed method provides reliable results, which are not burdened with significant errors and distortions resulting from the proposed measurement methodology or from the construction of the measurement system itself. The developed system does not require significant financial outlays and is a perfect complement to the stationary measurements currently performed within the Environmental Monitoring System. Med Pr. 2019;70(5):567-85.

Mitigation measures of electromagnetic field exposure in the vicinity of high frequency welders

BACKGROUND

Presented information about the welding process and equipment, focusing on the emission of electromagnetic field (EMF) with levels significant in terms of the labor safety regulations in force in Poland - the ordinances of the Minister of Family, Labour and Social Policy that came into force on June 27, 2016 and June 29, 2016 - emerged due to harmonization with European Union directive 2013/35/EU of 26 June 2013 of the European Parliament and the Council. They presented methods of determination of the EMF distribution in the welding machine surroundings and analyzed the background knowledge from the available literature.

MATERIAL AND METHODS

The subject of the analysis included popular high frequency welders widely used in the industry. Electromagnetic field measurements were performed in the welder operating place (in situ) during machine normal operations, using measurement methods accordant with labor safety regulations in force in Poland and according to the same guidelines, the EMF distributions and parameters having been described.

RESULTS

They presented various scenarios of particular, real examples of excessive exposure to EMF in the dielectric welder surroundings and showed solutions, ranging from simple and costless and ending on dedicated electromagnetic shielding systems, which allowed to reduce EMF exposure in some cases of more than 80% (protection zone ranges) or eliminate dangerous zone presence.

CONCLUSIONS

It has shown that in the dielectric welders surrounding, significant EMF strength levels may be the result of errors or omissions which often occur during development, installation, operation or modification of welding machines. It has allowed to present the measures that may significantly reduce the exposure to EMF of workers in the welder surroundings. The role of accredited laboratories in helping in such cases was underlined. Med Pr 2017;68(6):693-703.

ADN-1184 a monoaminergic ligand with 5-HT(6/7) receptor antagonist activity: pharmacological profile and potential therapeutic utility

BACKGROUND AND PURPOSE

Many dementia patients exhibit behavioural and psychological symptoms (BPSD) that include psychosis, aggressivity, depression and anxiety. Antipsychotic drugs are frequently prescribed but fail to significantly attenuate mood deficits, may interfere with cognitive function and are associated with motor and cardiac side effects, which are problematic in elderly patients. A need therefore exists for drugs that are better suited for the treatment of BPSD.

EXPERIMENTAL APPROACH

We used in vitro cellular and in vivo behavioural tests to characterize ADN-1184, a novel arylsulfonamide ligand with potential utility for treatment of BPSD.

KEY RESULTS

ADN-1184 exhibits substantial 5-HT6 /5-HT7 /5-HT2A /D2 receptor affinity and antagonist properties in vitro. In tests of antipsychotic-like activity, it reversed MK-801-induced hyperactivity and stereotypies and inhibited conditioned avoidance response (MED = 3 mg·kg(-1) i.p.). Remarkably, ADN-1184 also reduced immobility time in the forced swim test at low doses (0.3 and 1 mg·kg(-1) i.p.; higher doses were not significantly active). Notably, up to 30 mg·kg(-1) ADN-1184 did not impair memory performance in the passive avoidance test or elicit significant catalepsy and only modestly inhibited spontaneous locomotor activity (MED = 30 mg·kg(-1) i.p.).

CONCLUSIONS AND IMPLICATIONS

ADN-1184 combines antipsychotic-like with antidepressant-like properties without interfering with memory function or locomotion. This profile is better than that of commonly used atypical antipsychotics tested under the same conditions and suggests that it is feasible to identify drugs that improve BPSD, without exacerbating cognitive deficit or movement impairment, which are of particular concern in patients with dementia.

Family-based and case-control study of glutamate receptor GRIK3 Ser310Ala polymorphism in alcohol dependence

AIM

The aim of this study was to evaluate the role of the glutamate receptor subunit-7 (GluR7, GRIK 3) rs6691840 (Ser310Ala, T928G) in the pathogenesis of alcohol dependence (AD).

METHODS

DNA was provided from AD patients (n = 209) and healthy control subjects (n = 308) all of Polish descent. The history of alcoholism was obtained using the Polish version of the SSAGA (Semi-Structured Assessment for the Genetics of Alcoholism). We conducted case-control association study and transmission disequilibrium test (TDT). GRIK3 functional polymorphism was genotyped by the PCR-RFLP method.

RESULTS

Analyses revealed that polymorphism Ser310Ala of GRIK3 gene is not associated with AD or any of its subgroups. TDT reveled an adequate transmission of both alleles in the group of alcohol families.

CONCLUSIONS

These findings replicate and extend our previous research results that do not support the hypothesis of the role of rs6691840 in the pathogenesis of AD.

[Electormagnetic field of the mobile phone base station: case study]

BACKGROUND

The paper presents changes in the electromagnetic field intensity in a school building and its surrounding after the mobile phone base station installation on the roof of the school.

MATERIAL AND METHODS

The comparison of EMF intensity measured before the base station was launched (electromagnetic background measurement) and after starting its operation (two independent control measurements) is discussed.

RESULTS

Analyses of measurements are presented and the authors also propose the method of the electromagnetic field distribution adjustment in the area of radiation antennas side lobe to reduce the intensity of the EMF level in the base station proximity. The presented method involves the regulation of the inclination.

CONCLUSIONS

On the basis of the measurements, it was found that the EMF intensity increased in the building and its surroundings, but the values measured with wide margins meet the requirements of the Polish law on environmental protection.

[Technical possibilities of estimating the environmental exposure to electromagnetic fields for biomedical investigations based on cellular telephony systems]

The work addresses technical aspects of the assessment of exposure to electromagnetic fields (EMF) in the environment based on cellular telephony systems. In this paper, EMF parameters, important to the biosphere exposure, are discussed, and the methods for the EMF assessment: theoretical analysis of EMF intensity in the proximity of EMF sources and also the measurements in situ, are described. The review of measurement methods, identification of limitations of measuring devices, estimation of the expected EMF intensity in the municipal environment and environmental measurements uncertainty are presented. M

[Electromagnetic fields emitted in radio- and microwave- frequency range: equipment and methods for the environment protection and survey measurements]

In the paper a review of electromagnetic field sources in radio- and microwave- frequency range is presented. The aim of the study was to analyze possibilities and methods used to survey electromagnetic field (EMF) measurements. Selective and broadband methods with examples of apparatus are described. The accuracy of typical EMF survey measurements was estimated.

[Reports on the impact of objects emitting electromagnetic fields on the environment: issues concerning their better understanding by non-specialists in telecommunication]

The paper presents issues concerning a better understanding of reports on the impact of objects emitting electromagnetic fields on the environment among non-specialists in telecommunication. A proposed universal model of the radiation pattern of antenna base stations to widen the information contained in environmental audits as well as a vocabulary of basic technical terms in colloquial language are discussed.

[Estimation of the restricted area related to the limitation of exposure of the general public to electromagnetic fields in the vicinity of microwave relay antenna systems]

BACKGROUND

The aim of the study was to analyze and modify methods used to estimate the range of restricted area corresponding with the limitation of exposure of the general public to electromagnetic fields in the vicinity of microwave relay antenna systems.

MATERIALS AND METHODS

In this paper a well known spherical-wave model is revised. Some drawbacks of this model in terms of the microwave relay antenna systems are shown and a method for their elimination is proposed. The idea of this method is based on placing an equivalent point source of radiation behind the actual antenna, and then on taking into account the power density produced by this source over the antenna aperture.

RESULTS

In the course of the study an algorithm for the range of restricted area estimation was developed. Some results of calculation validating the proposed method are presented.

CONCLUSIONS

The proposed model and algorithm for the range of restricted area estimation may be employed in administrative procedures for evaluating the effects exerted on the environment. The proposed method can be regarded as an alternative to the presently employed spherical wave approach in the case of the microwave relay antenna systems.

[Electromagnetic fields measurements to assess workers' exposure and environmental protection: interlaboratory comparisons]

Interlaboratory comparisons (ILC) are an important element of quality systems of certified testing laboratories. It is the policy of the majority of certifying institutions to participate in ILC programs concerning research laboratories. ILC programs are technical initiatives. An analysis of the ILC results allows for taking decisive actions-proficiency testing. There are many types of ILC. However, in EMF measurements, the result comparison programs are usually applied. All program participants measure the same EMF source, usually the one that is normally exploited. The authors present the results and analysis of interlaboratory comparisons performed by certified laboratories. Comparisons presented in the paper were performed in the vicinity of the GSM base station.

[Verification of Polish regulations of maximum permissible intensities in electromagnetic fields by the Commission for Bioelectromagnetic Issues of the Polish Radiation Research Society]

Experts in the field of bioelectromagnetism have reported a growing need to verify Polish regulations on the protection against electromagnetic fields (EMF) in the 0-300 GHz range, especially in their maximal permissible intensities (MPI). There is a general belief that Polish standards do not fully comply with recommendations and directives of the European Union (EU) and that Polish regulations on the border values for environmental and occupational exposure to EMF are not harmonized. To this end, the Commission for Bioelectromagnetic Issues have been set up in the Polish Radiation Research Society. Following a through analysis of standards binding in Poland and EU, the Commission set about working on verified MPI values for EMF. This paper presents some comments of the Commission members, stressing the complexity of this undertaking.

Procedure for rehabilitation of the knee following synovectomy in patients with rheumatoid arthritis at the Poznań Rheumatological Center in Srema

At the Poznań Rheumatology Center in Srema synovectomy of the knee joint is one of the treatment methods applied in cases where "rheumatoid granules" occur in the knee, or in recurrent exudative infections. One of the essential elements of therapy is to begin post-operative rehabilitation with active exercises as soon as 48 hours after surgery. This method is used to eliminate adhesions in the operating field and achieve a full range of movement in the joint without the need to apply painful and injurious redressing of the joint. The procedure used with the patient after surgery and the choice of kinesitherapeutic methods is the result of many years of experience. Post-operative procedures are concluded within 2-3 weeks when the range of movement achieved in the joint is greater than or equal to pre-operative.

[Ototoxic mechanism of aminoglycoside antibiotics--role of glutaminergic NMDA receptors]

Recent studies have indicated that glutamatergic NMDA receptors in the cochlea may be involved in ototoxic effects of aminoglycosides in animal subjects. Aminoglycoside antibiotics enhance the function of NMDA receptors by interaction with a polyamine modulatory site. Accordingly, high doses of aminoglycosides may increase calcium entry through the NMDA receptor-associated channel and promote degeneration of hair cells and cochlear nerve fibers. In line with the above, a polyamine site antagonist, ifenprodil as well as a high-affinity channel blocker, dizocilpine (MK-801) attenuates ototoxic effects of aminoglycosides in rats. Notably, ifenprodil as well as low-affinity channel blockers (e.g. memantine and amantadine) may be safely used in humans. Taken together, the above findings seem to open new avenues of research on selective pharmacotherapy of aminoglycosides-induced ototoxicity in humans.

An opioid receptor antagonist, naltrexone, does not alter taste and smell responses in humans

Several studies have shown that an opioid receptor antagonist, naltrexone, decreases palatable food consumption. Naltrexone has also been reported to reduce ethanol intake in alcohol-preferring rodents and human alcoholics. The aim of the present study was to assess the effects of naltrexone on taste and smell responses in healthy male volunteers. Naltrexone did not alter intensity and pleasantness of sucrose, quinine, citric acid, sodium chloride, and ethanol taste. Similarly, ratings of olfactory stimuli (orange extract and ethanol) and Coca-Cola flavor were not influenced by the opioid antagonist. Our findings may indicate that: (i) naltrexone exerts marginal, if any, effects on gustatory and olfactory responses in humans; (ii) the drug does not alter orosensory responses to ethanol.

Discriminative stimulus effects of ethanol: neuropharmacological characterization

Generally, compounds discriminated by animals possess psychotropic effects in animals and humans. As with many other drugs of abuse, strength of the ethanol discriminative stimulus is dose related. The majority of studies show that doses close to 1.0 g/kg are close to the minimum at which the discrimination can be learned easily. Substitution studies suggest that anxiolytic, sedative, atactic, and myorelaxant effects of ethanol all play an important role in the formation of its intercoeptive stimulus. Low doses of ethanol produce more excitatory cues, similar to amphetamine-like subjective stimuli, whereas higher doses produce rather sedative/hypnotic stimuli similar to those elicited by barbiturates. Substitution studies have shown that the complete substitution for ethanol may be exerted by certain GABA-mimetic drugs acting through different sites within the GABA(A)-benzodiazepine receptor complex (e.g., diazepam, pentobarbital, certain neurosteroids), gamma-hydroxybutyrate, and antagonists of the glutamate NMDA receptor. Among the NMDA receptor antagonists both noncompetitive (e.g., dizocilpine) and competitive antagonists (e.g., CGP 40116) are capable of substituting for ethanol. Further, some antagonists of strychnine-insensitive glycine modulatory sites among the NMDA receptor complex (e.g., L-701,324) dose-dependently substitute for the ethanol discriminative stimulus. On the other hand, neither GABA-benzodiazepine antagonists nor NMDA receptor agonists produce contradictory effects (i.e., reduce the ethanol discriminative stimulus). There is influence of a particular training dose of ethanol on the substitution pattern of different compounds. For example, 5-HT(1B/2C) agonists substitute for intermediate (1.0 g/kg) but not higher (2.0 g/kg) ethanol training doses. Discrimination studies with ethanol and drugs acting on NMDA and GABA receptors consistently indicate asymmetrical generalization. For example, ethanol is able to generalize to barbiturates and benzodiazepines, but neither the benzodiazepine nor barbiturate response generalizes to ethanol. Only a few drugs are able to antagonize, at least to some extent, the discriminative stimulus of ethanol (e.g., partial inverse GABA-benzodiazepine receptor antagonist Ro 15-4513 and the opioid antagonist naloxone). The ethanol stimulus effect may be increased (i.e., stronger recognition) by N-cholinergic drugs (nicotine), dopaminergic drugs (apomorphine), and 5-HT3 receptor agonists (m-chlorophenylbiguanide). Thus, the ethanol stimulus is composed of the several components, with the NMDA receptor and GABA(A) receptor complex being of particular importance. This suggests that a drug mixture may be more capable of substituting for ethanol (or block its stimulus) than a single compound. The ability of drugs to substitute for the ethanol discriminative stimulus is frequently, although not preclusively, associated with the reduction of voluntary ethanol consumption. The examples of positive correlation are gamma-hydroxybutyrate, possibly memantine and certain serotonergic drugs such as fluoxetine. However, it remains uncertain to what extent the discriminative stimulus of ethanol can be seen as relevant in the understanding of the complex mechanisms of dependence.

Studies of the effect of simulated acid rain on the ecological equilibrium of the soil system

Introduction to the problem of environmental pollution caused by acid depositions. Presentation of principles of the six-year field experiment with simulated acid rain. Short characteristics of particular parts of the series of papers.