ABSTRACT
Age related impairments in behavioral functions following lead (Pb) exposure have been linked to changes in neurotransmitter levels in brain regions. In the present study, we have evaluated the protective effect of a mixture of essential elements containing calcium, zinc and iron against Pb-induced long-term effects on aminergic system and behavior of rats. Rats were lactationally exposed to Pb (0.2%) or Pb acetate together with nutrient metal mixture (0.02% Ca, Zn and Fe) in drinking water of the mother from postnatal day (PND) 1 to PND 21. Increases in synaptosomal dopamine, epinephrine, norepinephrine and serotonin levels and decrease in mitochondrial monoamine oxidase (MAO) in cortex, cerebellum, and hippocampus regions were observed following Pb exposure in different age groups (PND 45, 4, 12 and 18 months) of rats. The alterations were greater in hippocampus than cortex and cerebellum. Total locomotor activity, exploratory and open field behaviors were also altered following Pb exposure. However, the alterations were maximum in PND 45 coinciding with greater blood Pb levels observed in PND 45. These data suggest that, Pb exposure induced age dependent alterations in motor behavior and synaptosomal aminergic system were significantly reversed with the supplementation of nutrient metal mixture suggesting therapeutic nature of essential metal supplements against Pb-induced toxicity.
Subject(s)
Biogenic Monoamines/metabolism , Brain/metabolism , Dietary Supplements , Lead/toxicity , Metals/pharmacology , Motor Activity/drug effects , Age Factors , Animals , Calcium/pharmacology , Female , Iron/pharmacology , Male , Monoamine Oxidase/metabolism , Pregnancy , Rats , Zinc/pharmacologyABSTRACT
Since alterations in monoamines and monoamine oxidase (MAO) have been postulated to play a role in toxic effects of lead (Pb) on the central nervous system, we have examined the protective effects of calcium (Ca2+) and zinc (Zn2+) supplementation on Pb-induced perturbations in the levels of monoamines and the activity of MAO. Swiss albino mice were lactationally exposed to low (0.2%) and high (1%) levels of Pb-acetate via drinking water of the mother. Pb-exposure commenced on postnatal day (PND) 1, continued up to PND 21 and stopped at weaning. Ca2+ or Zn2+ (0.02% in 0.2% Pb-water or 0.1% in 1% Pb-water) was supplemented separately to the mother up to PND 21. The levels of monoamines (epinephrine, norepinephrine, dopamine and serotonin) and the activity of MAO in the brain regions such as hippocampus, cortex, cerebellum and medulla of young (1 month old) and adult (3 month old) mice were determined in the synaptosomal fractions. The synaptosomal monoamines though increased with low level (0.2%) Pb-exposure, significantly decreased with high level (1%) Pb-exposure in all the brain regions in both the age groups. In general, the young mice seem to be more vulnerable to Pb-neurotoxicity. Ca2+ or Zn2+ supplementation significantly reversed the Pb-induced perturbations both in the levels of monoamines and in the activity of MAO. However, the recovery in monoamine levels and MAO activity was more pronounced with Ca2+ supplementation as compared to Zn2+. These results provide evidence that dietary Ca2+ and/or Zn2+ provide protection against Pb-induced neurotoxic effects.
Subject(s)
Brain/drug effects , Brain/growth & development , Calcium/administration & dosage , Lead Poisoning, Nervous System/prevention & control , Lead/toxicity , Zinc/administration & dosage , Animals , Animals, Suckling , Biogenic Monoamines/chemistry , Biogenic Monoamines/metabolism , Brain/metabolism , Brain Chemistry/drug effects , Drug Administration Routes , Female , Lead Poisoning, Nervous System/drug therapy , Lead Poisoning, Nervous System/metabolism , Male , Maternal Exposure , Mice , Monoamine Oxidase/metabolism , Reproducibility of Results , Sensitivity and Specificity , Spectrophotometry, Ultraviolet/methods , Synaptosomes/drug effects , Synaptosomes/enzymologyABSTRACT
Administration of the defensive secretion of the grasshopper, Poecilocerus pictus inhibited acetyl-cholinesterase (AChE) and adenosine triphosphatases (ATPases) in the brain and muscle tissues of the garden lizard, Calotes nemoricola. The inhibition was gradual, continuous and irreversible with lethal doses of the defensive secretion, whereas the inhibition observed with sublethal doses was followed by an increase towards control levels within 24 h after injection. In vitro application of defensive secretion also showed concentration-dependent inhibition in the activity of AChE and ATPases in the tissue homogenates. Inhibition in AChE activity might be a factor for the observed mortality is the defensive fluid-treated lizards. Since the cardenolides are known to inhibit the activity of ATPases, the inhibition in the activity of ATPases observed in the present study suggests the presence of cardenolides in the defensive fluid of P. pictus.
