Lead exposure, environmental temperature, nesting and consummatory behavior of adult male mice of two ages

Are NCAM deficient mice an animal model for schizophrenia?

Genetic and biomarker studies in patients have identified the Neural Cell Adhesion Molecule (NCAM) and its associated polysialic acid (PSA) as a susceptibility factors for schizophrenia. NCAM and polysialtransferase mutant mice have been generated that may serve as animal models for this disorder and allow to investigate underlying neurodevelopmental alterations. Indeed, various schizophrenia-relevant morphological, cognitive and emotional deficits have been observed in these mutants. Here we studied social interaction and attention of NCAM null mutant (NCAM^−/−) mice as further hallmarks of schizophrenia. Nest building, which is generally associated with social behavior in rodents, was severely impaired, as NCAM^−/− mice continuously collected smaller amounts of nest building material than their wild type littermates and built nests of poorer quality. However, social approach tested in a three—compartment—box was not affected and latent inhibition of Pavlovian fear memory was not disturbed in NCAM^−/− mice. Although NCAM deficient mice do not display a typical schizophrenia-like phenotype, they may be useful for studying specific endophenotypes with relevance to the disease.

Effect of environmental temperature on tissue lead accumulation in mice repeatedly treated with lead acetate

The effect of environmental temperature on lead accumulation in tissues of mice repeatedly treated with lead acetate (2 mg/kg per day and 5 mg/kg per day) for 3 or 6 weeks was studied. In blood, kidney and liver, the amount of lead accumulated after 3 weeks of treatment was markedly higher in animals exposed to 22 degrees C than those maintained at 35 degrees C. Conversely, when the treatment was extended to 6 weeks, lead concentrations in the liver and kidney were equal or higher respectively, in the mice exposed to 35 degrees C. In the brain, lead concentration was lower than that found in kidney and liver and it was independent of dose and ambient temperature of lead being higher at 35 degrees C than at 22 degrees C. These results demonstrate that environmental temperature influences the amount of lead accumulated in some rodent tissues, and that the duration of the treatment modifies the effect produced by temperature, suggesting that the changes elicited during the period of acclimation to the hot environment could be responsible for these findings.

Pre- and postnatal lead exposure affects the serotonergic system in the immature rat brain

The effect of pre- and postnatal lead exposure on the development of the serotonergic system in striatum and brain stem was investigated. Serotonin and its metabolite 5-HIAA where determined by HPLC-EC. A significant decrease of 5-HT was detected in the brain stem at postnatal day 28. At both days 6 and 28 postnatal, 5-HIAA was reduced in striatum and brain stem. The results provide support to the hypothesis that developing 5-HT neurons are sensitive to relatively low levels of lead exposure.

Prenatal nicotine exposure increased susceptibility to electroconvulsive shock (ECS) in adult rats

Female rats were treated during pregnancy (days 1-20) with nicotine (1 mg/kg SC, b.i.d.). When some aspects of maternal behavior and developmental parameters were recorded in mothers and pups, respectively, no changes were detected in the experimental group as compared with controls. However, adult offspring of nicotine-treated rats showed an increased susceptibility to ECS. These results demonstrate long-lasting deleterious effects induced by nicotine exposure during fetal life.

Short term lead exposure, age and food deprivation: interactive effects on wheel running behavior of adult male mice

In three separate experiments, young-adult (75 days old) intermediate-age (220 days old), or older (365 days old) Binghamton Heterogeneous Stock (HET) male mice were maintained on food and either water or a 0.5% lead-acetate drinking solution for only three weeks prior to placement in cages with attached running wheels. Mice were kept on their assigned sources of fluid while in these wheeled cages for six days. On Days 3 and 4 of their 6-day access to the running wheels all mice were deprived of food, but the appropriate drinking fluid remained available continually. Even with this relatively low level of dietary lead exposure, which occurred only during adulthood and immediately prior to (and continued during) the 6-day measurement period, the 48-hour food deprivation challenge differentially altered the wheel running of lead-exposed and control mice; but those effects were apparently altered by the age of the adult mice used in each of the three experiments. These data are discussed in terms of the potency of environmental challenges in revealing behavioral changes related to age and even short-term exposure to environmental/dietary toxicants during adulthood.