Korean J Physiol Pharmacol.  2019 Nov;23(6):467-474. 10.4196/kjpp.2019.23.6.467.

Influence of clozapine on neurodevelopmental protein expression and behavioral patterns in animal model of psychiatric disorder induced by low-level of lead

• Lee H
• Lee M
• Kim HK
• Kim YO
• Kwon JT
• Kim HJ

• KMID: 2461039
• DOI: http://doi.org/10.4196/kjpp.2019.23.6.467

Abstract

Exposure to lead during pregnancy is a risk factor for the development of psychiatric disorders in the offspring. In this study, we investigated whether exposure to low levels of lead acetate (0.2%) in drinking water during pregnancy and lactation causes behavioral impairment and affects the expression of proteins associated with neurodevelopment. Lead exposure altered several parameters in rat offspring compared with those unexposed in open-field, social interaction, and pre-pulse inhibition tests. These parameters were restored to normal levels after clozapine treatment. Western blot and immunohistochemical analyses of the hippocampus revealed that several neurodevelopmental proteins were downregulated in lead-exposed rats. The expression was normalized after clozapine treatment (5 mg/kg/day, postnatal day 35-56). These findings demonstrate that downregulation of several proteins in lead-exposed rats affected subsequent behavioral changes. Our results suggest that lead exposure in early life may induce psychiatric disorders and treatment with antipsychotics such as clozapine may reduce their incidence.

Keyword

Animal model; Behavior rating scale; Clozapine; Lead poisoning; Neurodevelopmental disorder

MeSH Terms

Animals*
Antipsychotic Agents
Behavior Rating Scale
Blotting, Western
Clozapine*
Down-Regulation
Drinking Water
Female
Hippocampus
Incidence
Interpersonal Relations
Lactation
Lead Poisoning
Models, Animal*
Neurodevelopmental Disorders
Pregnancy
Rats
Risk Factors
Antipsychotic Agents
Clozapine
Drinking Water

Figure

• 

  Fig. 1 Prepulse inhibition (PPI) in adult male rats was analyzed on post-natal day 56 after exposure to lead stress during gestation or in male rats derived from unstressed litters during gestation. (A) The prepulse at intensities of 3, 6 and 12 dB were applied above the background noise preceded the onset of the 120 dB pulse. (B) The mean percent PPI values. Each group comprised 10 male rats. Each bar represents the mean of 10 male rats (± standard deviation); *p < 0.05 compared to the control group; **p < 0.05 compared to clozapine treatment group; LEAD, lead-exposed offspring during prenatal and lactation periods; CON, non-lead exposed offspring; LEAD-CLZ, lead-exposed and clozapine-treated offspring.

• 

  Fig. 2 Western blot analysis of Dpysl2, Nefm, and Dlg4 expression in brains of lead-exposed rats. (A) The expression of Dpysl2, Nefm, and Dlg4 was detected by western blot analysis. β-tubulin (Tubb) was used as an internal control. Lead-exposed rats demonstrated decreased hippocampal expression of Dpysl2, Nefm, and Dlg4 compared to control rats. Decreased expression of Dpysl2, Nefm and Dlg4 was restored (p < 0.05) by clozapine treatment. (B) The bar graph showing standard deviation (SD) (p < 0.05 compared to lead-exposed group). (C) The bar graph showing SD (p < 0.05 compared to lead-exposed group). (D) The bar graph showing SD (p < 0.05 compared to lead-exposed group). HIPP, Hippocampus; LEAD, leadexposed offspring during prenatal and lactation periods; CON, non-lead exposed offspring; LEAD-CLZ, offspring exposed to lead and clozapine treatment. *p < 0.05 Between CON with LEAD; **p < 0.05 Between LEAD with LEAD-CLZ.

• 

  Fig. 3 Immunohistochemical analysis of Dpysl2 expression in the brains of lead-exposed rats. (A) Confocal microscopic image showing immunofluorescent staining of Dpysl2 (anti-Dpysl2, red, Cy3) with NeuN (anti-NeuN, green, FITC) in the hippocampus. Dpysl2 fluorescent staining intensity was decreased in these regions. Scale bar, 50 µm. (B) The bar graph showing standard deviation (SD) (p < 0.05 compared to lead-exposed group). (C) Confocal microscopic images showing immunofluorescent staining of Nefm (anti-Nefm, green, FITC) with DAPI (blue) in the hippocampus. The fluorescent staining intensity of Nefm was decreased in these regions. Scale bar, 50 µm. (D) The bar graph showing SD (p < 0.05 compared to the PNS group in the hippocampus). LEAD, lead-exposed offspring during prenatal and lactation periods; CON, non-lead-exposed offspring; LEAD-CLZ, off-spring exposed to lead and treated with clozapine. *p < 0.05 Between CON with LEAD; **p < 0.05 Between LEAD with LEAD-CLZ.

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