Effects of a 30 kV/m, 60 Hz electric field on the social behavior of baboons: a crossover experiment

Using a crossover experimental design, we evaluated our earlier findings that exposure to a 30 kV/m, 60 Hz electric field for 12 hours per day, 7 days per week for 6 weeks produced significant changes in the performance rates of social behaviors among young adult male baboons. In the crossover experiment, the former control group was exposed to a 30 kV/m, 60 Hz electric field for 3 weeks. Only an extremely small, incidental magnetic field was generated by the exposure apparatus. We found that electric-field exposure again produced increases in the performance rates that index Passive Affinity, Tension, and Stereotypy. These findings, combined with results from our other electric-field experiments, indicate that exposure to strong electric fields, in the absence of associated magnetic fields, consistently produces effects that are expressed as increases in rates of performance of social behaviors in young adult male baboons.

Long-term, low-level microwave irradiation of rats

Our goal was to investigate effects of long-term exposure to pulsed microwave radiation. The major emphasis was to expose a large sample of experimental animals throughout their lifetimes and to monitor them for effects on general health and longevity. An exposure facility was developed that enabled 200 rats to be maintained under specific-pathogen-free (SPF) conditions while housed individually in circularly-polarized waveguides. The exposure facility consisted of two rooms, each containing 50 active waveguides and 50 waveguides for sham (control) exposures. The experimental rats were exposed to 2,450-MHz pulsed microwaves at 800 pps with a 10-microseconds pulse width. The pulsed microwaves were square-wave modulated at 8-Hz. Whole body calorimetry, thermographic analysis, and power-meter analysis indicated that microwaves delivered at 0.144 W to each exposure waveguide resulted in an average specific absorption rate (SAR) that ranged from 0.4 W/kg for a 200-g rat to 0.15 W/kg for an 800-g rat. Two hundred male, Sprague-Dawley rats were assigned in equal numbers to radiation-exposure and sham-exposure conditions. Exposure began at 8 weeks of age and continued daily, 21.5 h/day, for 25 months. Animals were bled at regular intervals and blood samples were analyzed for serum chemistries, hematological values, protein electrophoretic patterns, thyroxine, and plasma corticosterone levels. In addition to daily measures of body mass, food and water consumption by all animals, O2 consumption and CO2 production were periodically measured in a sub-sample (N = 18) of each group. Activity was assessed in an open-field apparatus at regular intervals throughout the study. After 13 months, 10 rats from each group were euthanatized to test for immunological competence and to permit whole-body analysis, as well as gross and histopathological examinations. At the end of 25 months, the survivors (11 sham-exposed and 12 radiation-exposed rats) were euthanatized for similar analyses. The other 157 animals were examined histopathologically when they died spontaneously or were terminated in extremis.

Rats are not aversive when exposed to 60-Hz magnetic fields at 3.03 mT

Thirty-two male rats were tested in two replicates of an experiment to determine whether body currents induced by 60-Hz magnetic fields might lead to avoidance behavior comparable to that which results from exposure to strong 60-Hz electric fields. The test apparatus was a two-compartment Plexiglas shuttlebox enclosed in a sound-attenuating plywood chamber, which in turn was encompassed by two copper bus bars that, when energized, served as a source of 60-Hz magnetic fields. Location of the rat, and traverse activity in the shuttlebox were monitored by nine infra-red photo detectors equally spaced along the length of the apparatus. Rats were divided into 2 groups: 1 group of rats (n = 8 per group per replicate) was sham exposed while rats in the other group (n = 8 per group per replicate) were exposed to a 3.03 mT (30.3 G), 60-Hz magnetic field whenever they traversed to or were located on the side (L or R) predetermined as the exposed side. To control artifact incident to side preference, the side exposed (L or R) was alternated over the exposed rats. Each rat was tested individually in a 1-h session. A 2-factor ANOVA (exposed vs. control, replicate 1 vs. replicate 2) failed to reveal any significant effects due to either factor or to an interaction between factors. These data demonstrate that rats do not avoid exposure to 60-Hz magnetic fields at a flux density of 3.03 mT and further imply that the avoidance by rats of high level 60-Hz electric fields is mediated by something other than the internal body currents induced by the exposure.

Bright light effects on body temperature, alertness, EEG and behavior

The immediate psychophysiological and behavioral effects of photic stimulation on humans [bright light (BL) of 5K lux or dim light (DL) of 50 lux] were assessed in male subjects (N = 43) under four different conditions. For one condition the same subjects (N = 16) received alternating 90-min blocks of BL and DL during the nighttime h (2300-0800 h) under sustained wakefulness conditions. A second condition was similar to the first except that subjects (N = 8) received photic stimulation during the daytime hours. For the third and fourth conditions different subjects received either continuous BL (N = 10) or continuous DL (N = 9) during the nighttime hours. For the nighttime alternating condition body temperature decreased under DL but either increased or maintained under BL. For the continuous light condition, body temperature dropped sharply across the night under DL but dropped only slightly under BL. Sleepiness was considerably greater under DL than under BL, and the difference became larger as the night progressed. Similarly, alertness, measured by EEG beta activity, was greater under BL, and nighttime performance on behavioral tasks was also generally better. There were no differential effects between BL and DL on any measure during the daytime. These data indicate that light exerts a powerful, immediate effect on physiology and behavior in addition to its powerful influence on circadian organization.

[Post-irradiation changes in the content of phospholipids and cyclic nucleotides in the mouse brain]

The effect of ionizing radiation (5, 20, 100, 200 and 400 Gy) on the content of phospholipids and cyclic nucleotides in the brain tissue has been studied in experiments on albino mice. During the development of evident behavioural disturbances in irradiated mice (2 h after irradiation with doses 100-400 Gy), significant changes were observed in the content of phosphatidylinositides and cyclic GMP. These changes may account for disturbances in the function of the central nervous system during cerebral forms of acute radiation injury.

[Behavioral effects of the combined chronic action of 9375 and 1765 MHz microwaves]

Combined pulse-discrete microwave irradiation (9375 and 1765 MHz, irradiance flux density to 375 microW/cm2, by 12 h/day for 4 months) caused faint inhibition of CNS in locomotion activity and defensive reflex parameters.

[Late sequelae of the effect of electromagnetic field on animals]

Simple and complex forms of behaviour, gas composition and acid-alkaline blood status in rats following exposure to the electro-static field (ESF) and iraionization, as well as in their offspring were studied. It has been found out, that ESF combined with the negative polarity air ionization damage motor and sex activity, conditioned-reflectory activity, changes blood indices. The observed disturbances in the organism of parent animals influenced fetus development.

Photoablating neuronal groups using an intracellularly aggregating dye

We report here on a new method to kill several selected neurons, using a modified fluorescence photoablation technique that does not require impaling any cells. Rather, we injected extracellularly the dye rhodamine 6-G, which is taken up by the cells. We made our injections into one side of a cockroach ganglion, after which the nearby cell bodies of individually known giant interneurons (GIs), as well as other cell bodies and many axons, became highly fluorescent. After this dye accumulation, we irradiated either the entire ganglionic region of the accumulated dye, or specifically the cell bodies of two identified GIs. After allowing over one week for axonal degeneration, both histological and behavioral tests confirmed that specifically the axons of the targeted illuminated cells had been killed.

Intracranial prolactin perfusion induces incubation behavior in turkey hens

Intracranial perfusion of ovine prolactin (oPrl) via osmotic pump in laying turkey hens caused a sudden onset in incubation behavior, defined as an increase in nest visits. The hens also displayed a gradual decrease in egg laying during the time they were receiving oPrl, another indicator of the onset of incubation. Circulating immunoreactive turkey Prl levels fell during the perfusion period, even though the hens were displaying persistent nesting activity and reduced egg laying. No effects on serum LH were noted. Perfusion of oPrl during the first 14 days of photostimulation delayed the onset of egg laying by several days. No effects on serum Prl or serum LH were noted. It is suggested that incubation behavior is facilitated by central levels of Prl.

Progressive behavioral changes in rats after exposure to low levels of ionizing radiation in utero

The deleterious effects of ionizing radiation on the developing brain may be not only prolonged but progressive. Fetuses were exposed to 0.75 Gy of ionizing radiation on gestational day 15 through whole body exposure of the pregnant rat. Three behavioral tests (gait analysis, continuous corridor activity and photographic analysis of sequences of behavioral acts) were performed at 1 and 3 months, postnatally. Body weight and thickness of the cerebral cortex of irradiated rats were 10-15 percent below controls throughout the period of study. Behavior in all tests was more affected at 3 months than at 1 month of age. Gait of control rats, as measured by the angle of advanced of hind feet, widened about 20 percent for males and 40 percent for females from 1 to 3 months, as expected, while, in irradiated rats, the angle widened only about 10 percent. Continuous corridor activity increased less than 10 percent in controls and about 35 percent in irradiated rats over the same period. In photographic analysis of behavior, controls increased their time spent standing by about 50 percent in males and 20 percent in females from 1 to 3 months of age. Irradiated males increased time standing only about 10 percent and irradiated females decreased about 30 percent over the same period. The data obtained in these experiments support other evidence that some behavioral alterations from perinatal exposure to radiation become more marked with maturation.

[Combined action of gamma and UHF radiation on conditioned reflex behavior of rats]

Dynamics of the conditioned behaviour of rats in a shuttle box was studied after combined exposure to Cs-gamma radiation (1 Gy, 1.32 Gy/min) and microwave radiation (2450 MHz, 1 mW/cm2, 3 h). The number of conditioned and interstimulus responses was found to decrease on day 5 after microwave + gamma irradiation and to increase on day 30 after gamma + microwave irradiation.

Role of the visual input in recovery of function following unilateral vestibular lesion in the goldfish. I. Short-term behavioural changes

Vestibular compensation, i.e. the partial or complete recovery of function following lesion of a labyrinth, has been suggested to be based on a multisensory substitution process involving vestibular, visual and somatosensory information. Teleost fish would seem ideal subjects for testing this proposal, because equilibrium orientation in the intact animal is largely under the bimodal control of the vestibular and visual systems. The role of the visual input in the compensation of behavioural deficits elicited by hemilabyrinthectomy (HL) was studied in goldfish maintained over the first two postoperative hours under different lighting conditions. HL caused severe postural and locomotory symptoms, which were the same or similar under all lighting conditions. The rate at which the various deficits disappeared, however, was dependent not only on the presence of light but also on its direction of incidence. Animals maintained under overhead illumination reached the criterion of successful compensation (completion of 5-min continuous and unimpaired swimming) within 10 min, whilst under unilateral illumination (90 degrees to the vertical) the time to criterion was significantly increased; animals exposed to illumination from below or infra-red illumination showed little or no signs of compensation up to 2 h after HL. It is concluded (1) that the immediately postoperative stage of vestibular compensation in the goldfish represents an integral part of the recovery process, within which all observable deficits can be compensated with remarkable rapidity; and (2) that the visual input is both necessary and sufficient for the compensation of the immediately postoperative deficits. We term this early stage of recovery the 'acute' phase and consider it to be based on a visual substitution process, whereby the missing labyrinthine input to the (partially) deafferented vestibular neurons is functionally replaced by visual afferents.

Role of the visual input in recovery of function following unilateral vestibular lesion in the goldfish. II. Long-term behavioural changes

Previous behavioural studies in our laboratory have demonstrated that the visual input is both necessary and sufficient for the acquisition of the acutely compensated state following hemilabyrinthectomy (HL) in the goldfish. Here we examine the role of the visual input in the maintenance of the compensated state. Exposure of acutely compensated animals to illumination from below (IFB) or infra-red illumination (IRI) elicited a decompensation: whereas IRI was no longer effective 4 days after HL, the susceptibility to IFB disappeared slowly over a number of weeks. Exposure of acutely compensated animals to unilateral illumination (UI) induced a highly asymmetrical dorsal light response 1 day after HL: tilt towards the ipsilateral side was extreme, whilst tilt towards the contralateral side was similar to preoperative values. This pronounced side difference decreased rapidly over the next 3 days and then more slowly over the following weeks and months. The findings show (1) that the maintenance of the acutely compensated state is temporarily dependent not only on the presence of light but also on its direction of incidence; and (2) that the visual-vestibular integration governing posture and locomotion is strongly biased in favour of the visual input to the lesioned side during the early postoperative period and subsequently returns to near preoperative values. The present results are compatible with the hypothesis that acute vestibular compensation in the goldfish is based on a visual substitution process. The latter is not permanent, however, the chronic course of compensation being characterized by a progressive decrease in reliance on visual cues. The observed changes in visual-vestibular integration with time are assumed to reflect modifications in inter- and/or extra-vestibular commissural systems by which the intact labyrinth gradually strengthens its control over the deafferented nuclear complex.

The effect of unilateral optic nerve section on retinal light damage in rats

The effect of unilateral optic nerve section on the susceptibility of rat photoreceptors to damage by constant light was studied. Optic nerves of albino rats were cut intracranially by a ventral approach, so as not to interfere with structures in the orbit of the eye, with the brain or with the blood supply to the retina. Two separate experiments were performed on unilaterally optic nerve sectioned rats from two different sources. One group was purchased from a commercial supplier and the other group was born and raised in 3 lux cyclic light in our laboratory. For 1-4 weeks after surgery they were exposed to either 1000 lux for 24 hr or 80 lux for 48 hr. Light damage was quantified by measuring the outer nuclear layer area remaining in histological sections through the vertical meridian of the retina. It was found that retinas with optic nerves cut suffered substantially less damage from light than did those with intact optic nerves. Sham operated rats suffered the same amount of damage as did the optic nerve intact retinas of rats with one nerve cut. The extent of protection was greatest in the region previously shown to be most susceptible to damage. The protection afforded by optic nerve section could not be explained on the basis of behavior or rhodopsin photochemistry. The possible role of heat-shock proteins and a neuromodulator is discussed.

[The functional activity of the central nervous system in the early postradiation periods after exposure to gamma quanta at different doses]

Behavioral reactions of rats at early postradiation period have been studied after irradiation in sublethal and lethal dose range. Changes in functional activity of the central nervous system develop in correlation with the stages of X-ray damage.

Febrile convulsions induced by microwaves and the alteration in behavior of albino mouse OF1

We studied the effects of microwave (2,440 MHz) induced febrile convulsions (FCs) on the behavior and development of 31 albino mice (OF1 strain), between 25 and 30 days old, in comparison with a group of 33 animals from the same litters. Previously a string test was adapted to measure the neurodevelopment of mice in the first 6 months of life with 82 animals of the same characteristics. The animals submitted to convulsions (fit temperature = 39.2 +/- 0.96 degrees C) showed normal growth, in fact they obtained better results in the test than the control mice (2-way ANOVA, p less than 0.01). FCs have no negative influence on the normal behavior of the mouse.

An animal model to study toxicity of central nervous system therapy for childhood acute lymphoblastic leukemia: effects on behavior

Central nervous system prophylactic therapy used in the treatment of acute lymphoblastic leukemia can reduce intelligence quotient scores and impair memory and attention in children. Cranial irradiation, intrathecal methotrexate, and steroids are commonly utilized in acute lymphoblastic leukemia therapy. How they induce neurotoxicity is unknown. This study employs an animal model to explore the induction of neurotoxicity. Male and female Sprague-Dawley rats at 17 and 18 days of age were administered 18 mg/kg prednisolone, 2 mg/kg methotrexate, and 1000 cGy cranial irradiation. Another 18-day-old group was administered 1000 cGy cranial irradiation but no drugs. Matching controls received saline and/or a sham exposure to radiation. All animals at 6 weeks and 4 months of age were tested for alterations in spontaneous behavior. A computer pattern recognition system automatically recorded and classified individual behavioral acts displayed during exploration of a novel environment. Measures of behavioral initiations, total time, and time structure were used to compare treated and control animals. A permanent sex-specific change in the time structure of behavior was induced by the prednisolone, methotrexate, and radiation treatment but not by radiation alone. Unlike hyperactivity, the effect consisted of abnormal clustering and dispersion of acts in a pattern indicative of disrupted development of sexually dimorphic behavior. This study demonstrates the feasibility of an animal model delineating the agent/agents responsible for the neurotoxicity of central nervous system prophylactic therapy.

Onset of behavioral effects in mice exposed to 10 Gy 60Co radiation

The effects of 10 Gray (Gy) 60 Co radiation on social behavior, locomotor activity, and body weight were assessed in individually housed male Swiss-Webster mice. In Experiment 1, aggressive behavior was evaluated prior to irradiation and for 7 d postirradiation by placing an untreated intruder in the irradiated or sham-irradiated resident's home cage for 5 min. Offensive aggressive behavior was not affected significantly by radiation until day 7 postirradiation, when attack latency increased, the frequency and duration of fighting decreased, and the frequency of bites, lunges, and chases decreased. Untreated intruder mice paired with irradiated resident mice showed a decrease in the duration of defensive upright postures and a decrease in the frequency of defensive upright postures, squeaks, and escapes on day 7 postirradiation. In Experiment 2, locomotor activity and body weight were monitored for 7 d postirradiation. Body weight was decreased in irradiated mice beginning 4 d postirradiation. Locomotor activity was suppressed in irradiated animals 90 min after irradiation and remained depressed throughout the 7-d testing period.

[State of the organ of vision and behavior of rats after action on the eye of increased doses of UV-irradiation]

Male Wistar rats, weighing on the average 200 g, were used to investigate the clinical picture of photokerato-conjunctivitis and behavioral responses to the open field test after exposing their eyes to UV-radiation with an emission maximum at 302 nm. The development threshold for conjunctivitis was 0.6 kJ/m2 and that for keratitis was 0.8 kJ/m2. The corneal lesions such as perforation and formation of persistent (up to 60 days) changes emerged beginning with the dose 3 kJ/m2 (in 50% of animals). This dose is a minimally acting dose in terms of behavior. At the dose of 10 kJ/m2 the decrease of the horizontal motor activity, which was significant from day 14, became irreversible. Thus when the organ of vision is exposed to UV-radiation, it is important to take into consideration not only structural changes but also potential functional disorders, which are associated with enhancement of inhibitory processes in the CNS.

[The effect of highly intensive irradiation on the functional status of the brain in monkeys]

In experiments with Macaca fascicularis a study was made of early manifestations of the central nervous system (CNS) disturbances caused by exposure to 24 MeV electrons (45 Gy). The results obtained permit us to distinguish two main ways (stereotypes) by which a clinical picture of early postirradiation period develops: "comatose" and "non-comatose". A general clinical characteristic of each stereotype and stages of their development are presented. The postirradiation disturbances of nervous and psychic activity of monkeys are considered within the framework of the concept concerning acute reactions of exogenous type. It is suggested that the course of the early postirradiation period is conditioned by the "involvement" of some phylogenetically determined, universal systemic mechanisms of the CNS response to external harmful effects.

[The effect of microwave irradiation on the status of the thyroid gland]

Multiple irradiation of rats with microwaves of continuous generation (2450 MHz, 1 mW/cm2) increased and of pulsed generation (3000 MHz, 0.1 to 2.5 mW/cm2) decreased the functional activity of the thyroid gland with no changes in the triiodothyronine and thyroxin in blood serum. The role of the thyroid gland in inducing behaviour effects of microwaves was demonstrated by the method of extirpation.

[The effect of an SHF field on the dopamine-dependent behavior of rats]

A study was made of the influence of SHF radiation (8 mW/cm2, carrier frequency 0.88 Hz, modulation frequency 16 Hz) on rotation of rats induced by apomorphine. A single exposure within an hour was shown to inhibit apomorphine-induced rotation by 21%. Daily one-hour exposure within 5 days caused a more pronounced inhibition of test-response. Different individual sensitivity to SHF radiation was noted.

Effects of ingestion of radioactive cesium on behavioral indices in rats

The experiments were carried out on 35 male (M) and female (F) rats contaminated by ingestion of Cesium--137(Cs) for 38 or 84 days; the total Cs activity was 288 Bq 460 Bq, and respectively. The duration of forced swimming decreased significantly in the contaminated groups as compared with controls (n = 16). The active avoidance reaction in the shuttle-box shows an increase in F groups and a decrease in M groups. The total latency time of the same reaction was lower in F and M treated rats on the first day of learning. The score of aggressive behavior rose significantly, especially in group F. These results can be explained by the sex dependence of Cs accumulation and by the neurotoxic action of the radionuclide on several central neural areas including monoaminergic and endocrine mechanisms.

Effect of light sources and light intensity on growth performance and behavior of male turkeys

This study consisted of two experiments: the first was conducted with Large White turkey males during the spring and summer (experiment 1) and the second during the autumn and winter (experiment 2). When 56 d of age, the birds were assigned to light-controlled pens and exposed to continuous illumination. Light sources used were incandescent, daylight fluorescent, warm fluorescent or high pressure sodium vapour lamps at light intensities of 10.8 or 86.1 lux. Results obtained showed that the light sources used had no significant effects on growth performance, efficiency of food utilization, feather scores or live bird quality of Large White turkeys. Social encounters were higher in birds reared under fluorescent and sodium vapour lights and mortality was higher in birds under fluorescent lights in experiment 1. Behaviour, feather scores, live bird grade and mortality were unaffected by light source treatments in experiment 2. Light intensity had no significant effect on growth, efficiency of food utilization, feather scores or bird market quality. Social encounters and mortality were higher in males exposed to 86.1 lux of light intensity.

[Cumulated biological effects of microwaves and their reflection in behavior, work capacity, growth of body mass and state of brain neurons]

Albino rats were exposed to 2375 mHz microwaves of 500 microW/cm2 for 169 h. At the time of exposure, the body mass growth diminished, the efficiency and vertical motor activity decreased in exposed animals in comparison with the controls. Three types of radiation-induced damages were found in the brain: chromatolysis, pyknosis, and ischemia. Different brain parts displayed different sensitivity depending on their location in relation to transverse sutures of the skull.