Robert L. Brunner

A developmental test battery for neurobehavioral toxicity in rats: a preliminary analysis using monosodium glutamate calcium carrageenan, and hydroxyurea.

Abstract A test battery for evaluating developmental neurobehavioral toxicity was designed to attempt to meet both the general requirements of a sound test system, namely, comprehensiveness, usability, and sensitivity and the specific requirements promulgated by Britain, France, and Japan as part of their reproductive guidelines for new drugs. Monosodium glutamate (MSG) and calcium carrageenan (CC) were used to obtain preliminary data with this test battery using continuous dietary exposure from prior to conception through 90 days of postnatal life. Observations were made on reproduction and on the physical and behavioral development of the offspring. Three dose levels were used with each of the food additives and the data from these subjects were compared to data from normally fed (negative) controls and a positive control group exposed to 550 mg/kg of hydroxyurea on the 12th day of gestation. Differences between MSG and negative control groups were observed in swimming development, open field, active and passive avoidance testing. Effects observed in the CC groups were inconsistent and not dose related. Prenatal treatment with hydroxyurea produced delayed startle and swimming development and reduced open field rearing activity. This pattern of effects was less than expected indicating that hydroxyurea is an adequate, but not optimal, positive control manipulation. It appears that the test protocol used in this research could, with some modification, serve as a usable screening technique for developmental neurobehavioral toxicity.

PHENYLKETONURIA AND COMPLEX SPATIAL VISUALIZATION: AN ANALYSIS OF INFORMATION PROCESSING

Recent neuropsychological studies have suggested that patients with early‐treated phenylketonuria (PKU) and normal intelligence have a specific deficiency in solving complex spatial problems. In the present study a task involving the assembly of various shapes was used to compare the performance of 16 PKU patients and 11 sibling controls. Error rates generally were higher and response times slower among the PKU patients, but greater complexity did not produce differential changes in accuracy or speed in the PKU group compared to the controls. Correlations between task performance and IQ measures were significant for the PKU patients, but when IQ was controlled for the group differences vanished. The results suggest that choice of problem‐solving strategy, attention span and accuracy of mental representation may be affected in PKU patients, despite efforts to maintain well‐controlled phenylalanine concentrations in the blood.

Developmental neurobehavioural toxicity of butylated hydroxytoluene in rats.

Abstract Butylated hydroxytoluene (BHT) was fed to rats throughout development (from before conception through to day 90 of postnatal life) at levels of 0, 0·125, 0·25 or 0·5% (w/w) in the diet. A similarly treated positive control group was injected on day 12 of gestation with 550 mg/kg of the antimitotic/embryotoxic drug hydroxyurea for reference. Offspring from all groups were reared by their natural dams and were evaluated in a battery of behavioural tests from day 3 to day 90 after birth. BHT at 0·5% in the diet reduced the body weights of dams and of offspring during early development and increased offspring mortality (to 39%) up to 30 days of age. This dose delayed eyelid opening, surface-righting development and limb co-ordination in swimming in males, and reduced female open-field ambulation; however, no significant effects were found after weaning. The lower doses of BHT produced some irregularities in maternal weight (0·25% an increase and 0·125% a decrease) but had no effect on the body weights of offspring. BHT at 0·25% of the diet increased pre- and periweaning mortality (23%), but neither this dose nor the 0·125% dose had any effect on physical or behavioural development or on post-weaning behavioural performance. The positive control group treated with hydroxyurea showed reduced growth prior to weaning, reduced adult brain weight and a slight but nonsignificant increase in pre- and periweaning mortality (10%). This group also exhibited delayed eyelid opening, delayed forward locomotor development and limb co-ordination during swimming, but showed no effects on postweaning behavioural performance. The BHT findings are consistent with the existing toxicological literature that BHT is toxic to growing rodents at doses of 0·25 or 0·5% of the diet with marginal effects at 0·125% of the diet. The behavioural data expand the picture of BHTs toxicity, but do not suggest any disproportionate or special toxicity of BHT for the central nervous system.

Preliminary support for the oral administration of valine, isoleucine and leucine for phenylketonuria.

Recent behavioral data have demonstrated the importance of maintaining low phenylalanine concentrations beyond early childhood in patients with phenylketonuria, which can be a difficult task, particularly during adolescence. Administration of certain large neutral amino‐acids (valine, isoleucine, leucine–VIL) appears to reduce phenylalanine concentrations in the cerebrospinal fluid of humans and in the brain of rats. The present study compared neuropsychological test‐performance of six patients with phenylketonuria during periods of VIL administration and periods when this supplement was not given. Although individual responses to VIL were variable, there was an over‐all improvement of about 1½ SD in neuropsychological test performance during VIL treatment. Abstract reasoning and tactile motor problem‐solving increased more than pure motor performance.

Developmental toxicity and psychotoxicity of FD and C red dye No. 40 (allura red AC) in rats.

Adult Sprague-Dawley rats were fed diets containing FD and C red dye No. 40 for 2 weeks and were then bred. The diets were continued for the females throughout gestation and lactation and were provided continuously to their offspring thereafter. The treatment groups were: FD and C red dye No. 40 as 0.0, 2.5, 5.0 or 10.0% of the diet, and a positive control group treated with the toxin hydroxyurea on days 2-10 of life with 50 mg/kg/day given s.c. as a positive control group. Parental animals were evaluated for weight and food consumption, and females for reproductive success. The offspring were assessed on a series of tests using the Cincinnati Psychoteratogenicity Screening Test Battery. Additional measures were weight, food consumption, physical landmarks of development, and brain weight. Red-40 significantly reduced reproductive success, parental and offspring weight, brain weight, survival, and female vaginal patency development. Behaviorally, R40 produced substantially decreased running wheel activity, and slightly increased postweaning open-field rearing activity. Overall, R40 produced evidence of both physical and behavioral toxicity in developing rats at doses of up to 10% of the diet.

A controlled study of type a behavior and psychophysiologic responses to stress in anorexia nervosa

Adolescents and young adults meeting DSM-III criteria for anorexia nervosa (n = 13) and atypical eating disorders (n = 7) were compared with weight-recovered anorectics (n = 6) and normal weight controls (n = 11) using a type-A structured interview and a computerized stress procedure. Heart rate, blood pressure, and electrocardiographic changes were monitored. Anorexia nervosa subjects demonstrated significantly more type-A characteristics than controls. The emaciated and weight-recovered anorectics had elevated hostility scores on the type-A interview, which has been shown in recent studies of type-A behavior to be a risk factor for cardiovascular disease. This pilot study is the first to demonstrate a significant relationship between anorexia and the type-A behavioral pattern. Also the anorectic subjects showed significantly more cardiovascular reactivity than controls as measured by failure of stressed anorectic subjects to lower their systolic blood pressure to baseline levels as controls did. These results support the importance of monitoring stress reactions and personality traits as well as traditional biological measures.

Developmental toxicity and psychotoxicity of sodium nitrite in rats

Sodium nitrite (NaNO2) was fed to male and female rats before and during breeding, to females only during gestation and lactation, and to their offspring after weaning (day 21 after birth) through day 90, at levels of 0, 0.0125, 0.025 or 0.05% (w/w) of the diet. Dams in a fifth group (positive controls) were given 4 mg/kg ip of the anti-mitotic/embryotoxic drug 5-azacytidine on day 16 of gestation. All offspring were reared by their natural dams and were evaluated blind with respect to treatment in a battery of standardized behavioural tests between 3 and 90 days of age. NaNO2 produced no significant reductions in parental body weight or food consumption, though it significantly increased offspring mortality and decreased weight gain at the two highest doses during the preweaning period. Functionally, NaNO2 delayed swimming development and decreased open-field activity. The open-field effect was not linearly dose dependent. In rats killed on day 90 after birth, NaNO2 produced no effects on brain or body weights. 5-Azacytidine produced evidence of substantially greater developmental toxicity than did NaNO2. NaNO2 produced a moderate degree of developmental toxicity, but no evidence was found to suggest that the central nervous system was the target organ for the toxic effects. The inclusion of tests of functional development added useful confirmatory evidence to the overall picture of NaNO2 toxicity.

Developmental toxicity and psychotoxicity of potassium iodide in rats: A case for the inclusion of behaviour in toxicological assessment

Potassium iodide (KI) was fed to male and female rats before and during breeding, to females only during gestation and lactation, and to their offspring after weaning (day 21 after birth) through to day 90, at levels of 0, 0.025, 0.05 or 0.1% (w/w) of the diet. Dams in a fifth group (positive controls) were given 4 mg/kg ip of the anti-mitotic/cytotoxic drug 5-azacytidine on day 17 of gestation. All offspring were reared by their natural dams and were evaluated blind with respect to treatment in a battery of standardized behavioural tests between 3 and 90 days of age. KI produced no significant reductions in parental body weight or food consumption, though it significantly reduced litter size and increased offspring mortality at the highest dose, and decreased weight gain at the two highest doses throughout the first 90 days after birth. Functionally, KI delayed auditory startle at the two highest doses, delayed olfactory orientation to the home-cage scent at the middle dose and decreased female running-wheel activity at all dose levels. In rats killed on day 90 after birth KI reduced brain and body weight at a dose of 0.1% of the diet, and reduced body but not brain weight at a dose of 0.05% of the diet. No significant effect was found on absolute or relative thyroid weight at 90 days of age. Several additional behavioural effects were observed in the low-dose KI group, but because these effects were not dose-dependent, they were not regarded as reliable. 5-Azacytidine produced evidence of substantially greater developmental toxicity than KI. It was concluded that KI produced evidence of developmental toxicity consistent with a picture of impaired thyroid function. The inclusion of tests of functional development added useful evidence to the overall picture of KI developmental toxicity.

A developmental toxicity and psychotoxicity evaluation of FD and C Red Dye #3 (erythrosine) in rats

Two experiments were conducted to evaluate FD and C Red Dye #3 for its developmental toxicity and psychotoxicity. Adult Sprague-Dawley rats were fed diets containing the dye for 2 weeks and were then bred. The diets were continued for the females throughout gestation and lactation and were provided continuously to their offspring thereafter. The treatment groups for Experiment 1 were Red Dye #3 as 0.0, 0.25, 0.5, or 1.0% of the diet (w/w), and a positive control group treated with the toxin hydroxyurea on days 2–10 of life (50 mg/kg/day, s.c.); Experiment 2 was a replication of Experiment 1 with the same dose groups, but without the positive control group. Parental animals were evaluated for weight and food consumption, and females for reproductive success. The offspring were assessed on a series of tests using the Cincinnati Psychoteratogenicity Screening Test Battery, plus weight, food consumption, physical landmarks of development, and brain weight. Red-3 produced no reductions in parental or offspring weight or food consumption. Red-3 significantly increased preweaning offspring mortality in the first experiment, but not in the second. Behaviorally, Red-3 produced no dose-dependent effects that replicated across the two experiments. It was concluded that no evidence was obtained that dietary exposure to FD and C Red Dye #3 (erythrosine) is psycho toxic to developing rats.

A cross-sectional study of behavior at three ages after neonatal X irradiation of the hippocampus

Juvenile (17–34 days of age), young adult (2–3 months) and adult rats (6–8 months) were tested for behavioral effects of focal, low-level X irradiation of the hippocampal region during the first two weeks after birth. The elimination of essentially all postnatally acquired granule cells of the dentate gyrus and the “syndrome” of hippocampal related behavioral changes were confirmed. In rats first tested in adulthood (6–8 months), only two components of the behavioral syndrome persisted. Adult X-irradiated rats continued to perform randomly in a spontaneous alternation task and had an extremely low rate of open-field defecation. It was hypothesized that with advancing age, X irradiation produced hyperactivity was reduced and behavioral differences which were dependent on heightened motor responsivity were diminished.