Consequences of lead exposure of rats during pregnancy, lactation, and postweaning. A combined behavioural and neurotoxicological study

Abstract

Behavioural and electrophysiological changes caused by inorganic lead treatment at different phases of the ontogenesis were investigated in Wistar rats. They were treated by gavage with 80.0, 160.0, and 320.0 mg/ kg lead during the 5th-15th days of pregnancy, or the 5th-15th days of pregnancy + 4 weeks of lactation (females of P generation), or the 5th-15th days of pregnancy + 4 weeks of lactation (females of P generation) + 8 weeks after weaning (males of F1 generation). The behavioural (open field) and electrophysiological (electrocorticog ram, cortical evoked potentials, etc.) parameters of F1 male rats in the above groups were investigated at the age of 12 weeks. Only rats exposed to lead during pregnancy exhibited a significant hyperactivity in the OF test expressed as a higher ambulation rate in the first minute in the OF and as longer running distances. Grooming was also increased. The spontaneous and evoked electrophysiological functions showed dose-and treatment-dependent changes (e.g. decreased mean amplitude and increased frequency of the electrocorticogram, lengthened latency and duration of the evoked potentials, etc.). The results indicate that the low-level pre-and postnatal inorganic lead exposure considerably affects both the behaviour and the function of the nervous system.

Comparative investigation of behavioral, neurotoxicological, and immunotoxicological indices in detection of subacute combined exposure with methyl parathion and propoxur in rats

“…The general trend of changes in the somatosensory evoked potentials were in line with previous findings of our laboratory (De´si and Nagymajte´nyi, 1999;Nagymajte´nyi et al, 1992Nagymajte´nyi et al, , 1994, in which the depression (increased latency and decreased amplitude) of cortical evoked potentials was found concomitant with increased spontaneous activity. The latter is under cholinergic modulation, as described, e.g., by Metherate et al (1992).…”

“…Their main target is the cholinesterase enzyme but, besides and partly beyond enzyme inhibition, some organophosphates can cause delayed neuropathy, behavioral and electrophysiological changes, and alterations in the immune system (WHO, 1986a). In our previous studies done in rats with dimethoate, methyl parathion, and dichlorvos, altered spontaneous cortical activity and modified latency and duration of sensory evoked potentials (De´si et al, 1994(De´si et al, , 1998Nagymajte´nyi, 1988, 1999;Nagymajte´nyi et al, 1992Nagymajte´nyi et al, , 1994, as well as changes in the behavior (Schulz et al, 1990) and in certain immune functions (Instito´ris et al, 1995a, b) of the animals, have been observed following subacute administration or in three-generation studies.…”