Content of lead and neurospecific proteins in blood and brain tissue, as well as features of sensorimotor reactions at different times after acute lead acetate intoxication

Abstract

Introduction. Lead is one of the most hazardous heavy metals for human health due to its effect on various metabolic pathways. The main target organs in lead poisoning are the hematopoietic and nervous systems, and the kidneys. Saturnism or lead poisoning at the level of the nervous system is manifested by damage to the brain and peripheral nerves. The aim of the study was to establish the dependence of lead neurotoxicity manifestations, detected by the dynamics of neurospecific proteins, impaired sensory response to stimuli of various modalities on its concentration in the blood and tissues.

Methodology. Laboratory animals (healthy nonlinear white male rats with a body weight of 180-220 g at the beginning of the study) were subjected to acute intoxication with lead acetate (300 mg/kg, which corresponds to the standard dose LD₅₀). On the 3rd, 15th and 29th days after acute intoxication, venous blood and tissue samples of the brain, kidneys, and liver were taken from the surviving animals, in which the lead concentration was determined. Also, on days 3 and 29, neurospecific proteins (NSE, BDNF, MBP and S100 protein) were determined in the blood serum, cerebrospinal fluid and brain tissue homogenate using the enzyme immunoassay method. In animals that survived acute intoxication, the response rates to sudden light, sound and electric current stimuli were determined using the TSE Startle Response System (TSE, Germany), a computerized test system for quantitative assessment of the startle reflex in laboratory animals. Sensory reactions of animals in response to three stimuli of different modality were recorded on days 3 and 29.

Results. The highest mortality rate of animals was observed on the second day of the post-intoxication period, when an increase in lead concentration in brain tissues to a critical level was recorded. Based on the mortality rates, an interesting fact was revealed that rats differ significantly in the level of individual sensitivity to the toxic effect of lead. Analysis of the concentration of neurotrophic proteins in the blood serum and tissues showed a negative effect of lead on the reparative system of the brain associated with neurotrophic factors. Neurophysiological test of the locomotor reaction to a sudden stimulus Startle Response System in animals that survived acute lead intoxication revealed depletion of the response to repeated exposure to light and sound stimuli at the stage of formation of remote consequences of acute intoxication.

Conclusion. It was revealed that the severity of the condition of animals and their death after acute poisoning with lead acetate does not depend on its concentration in the blood. It was suggested that neuron bodies are more sensitive to the toxic effect of lead than neuroglial cells.