Effect of Perinatal Lead Exposure on Rat Behaviour in Open‐Field and Two‐Wky Avoidance Tasks

Abstract

In view of conflicting results in literature concerning lead exposure associated with behavioural alterations, this study investigated behaviour in the open-field and shuttle avoidance, for as well as tissue lead burdens of pre- and postnatally lead-exposed rats. Rats were exposed to the metal from conception to weaning by giving the dams 0.5, 2.0 or 4.0 mM lead acetate in drinking water. This regimen did not affect body weight gain of dams or offspring development and had no effect on cerebral weights nor on haematological parameters of 23-day-old rats. In 1-day-old rats, lead accumulated in the blood but not in the brain, whereas both in 23-day-old rats and in dams lead accumulated in blood, kidney and cerebral cortex. In the open-field, lead-exposed groups showed higher locomotor activity in the test session as compared to controls and did not show any decrease in rearing responses in the test, indicating less habituation. Lead-treated rats subjected to a shuttle avoidance task showed no significant increase in avoidance responses between sessions as compared to control, indicating less retention. Moreover, only the control group presented a significant reduction of the footshock escape latency along testing session, suggesting a lead effect on footshock escape acquisition. In the shuttle box, intertrial crossing responses were not affected by lead treatment. The behavioural alterations occurred in animals with blood lead levels in the range 11-50.6 micrograms/dl.

Antidepressant-like effect of lead in adult mice

“…This indicates that all except Pb-MK-801 had memory of habituation. These results show that the lead-exposure regimen used in the present study did not cause impairment of memory of habituation per se, in contrast to the result obtained by us with young rats exposed to lead (9). This was probably due to the fact that adult rodents are more resistant to the effects of lead on memory than young rodents (1,2).…”

“…The numbers of squares crossed with all paws (crossings) and of standing on the hind legs (rearings) were scored in the sessions. The number of crossings indicated locomotor activity and the decrease in the number of rearings between sessions was taken to be a measure of habituation (9,10).…”

Effects of lead and/or zinc exposure during the second stage of rapid postnatal brain growth on delta-aminolevulinate dehydratase and negative geotaxis of suckling rats

“…One-way ANOVA followed by the Newman-Keuls test showed a reduction in hematocrit values in the groups treated with lead and with lead + zinc as compared to the control group (F(3,42) = 6.38, P<0.01). A reduction in hematocrit has also been previously reported in adult rats chronically exposed to lead (19), but, to our knowledge, has not been reported in young rats exposed to the metal during a specific stage of brain development which also corresponds to a period of intense tissue development. The reduction in the hematocrit of rats exposed to lead early during development seems to be a sensitive indicator of lead exposure and is not affected by zinc.…”

Antidepressant-like effects of magnesium lithospermate B in a rat model of chronic unpredictable stress

“…The number of crossings (squares crossed with all paws) was recorded during a test period of 5 min. This apparatus was cleaned with a detergent and dried after occupancy by each rat (Rodrigues et al, 1996).…”