Low-level repeated exposure to diazinon and chlorpyrifos decrease anxiety-like behaviour in adult male rats as assessed by marble burying behaviour

Abstract

Occupational exposure to organophosphate (OPs) pesticides is reported to increase in the risk of developing anxiety and depression. Preclinical studies using OP levels, which inhibit acetylcholinesterase activity, support the clinical observations, but little is known of the effects of exposure below this threshold. We examined the effects of low level OP exposure on behaviours and neurochemistry associated with affective disorders. Adult rats were administered either diazinon (1 mg/kg i.p.) which is present in sheep dip and flea collars, chlorpyrifos (1 mg/kg i.p.) which is present in crop sprays, or vehicle for 5 days. OP exposure did not affect acetylcholinesterase activity (blood, cerebellum, caudate putamen, hippocampus, prefrontal cortex), anhedonia-like behaviour (sucrose preference), working memory (novel object recognition), locomotor activity or anxiety-like behaviour in the open field arena. In contrast OP exposure attenuated marble burying behaviour, an ethological measure of anxiety. The diazinon-induced reduction in marble burying persisted after exposure cessation. In comparison to vehicle, dopamine levels were lowered by chlorpyrifos, but not diazinon. 5-HT levels and turnover were unaffected by OP exposure. However, 5-HT transporter expression was reduced by diazinon suggesting subtle changes in 5-HT transmission. These data indicate exposure to occupational and domestic OPs, below the threshold to inhibit acetylcholinesterase, can subtly alter behaviour and neurochemistry.

Sub-chronic exposure to diazinon induce cognitive impairment, alternations in amyloid precursor proteins, and TNF-α expression in the hippocampus of adult rats

“…The result obtained from the EPM and OFT tests illustrated that sub-chronic exposure to low-dose DZN increased anxiety-like behavior showed by decreased motor activity. These data were in line with previous ndings on the association of exposure with OPs and anxiogenesis (Baltazar et al 2014;Savy et al 2015).…”

Sub-chronic exposure to diazinon induce cognitive impairment, alternations in amyloid precursor proteins, and TNF-α expression in the hippocampus of adult rats

“…The result obtained from the EPM and OFT tests illustrated that sub-chronic exposure to low-dose DZN increased anxiety-like behavior showed by decreased motor activity. These data were in line with previous ndings on the association of exposure with OPs and anxiogenesis (Baltazar et al 2014;Savy et al 2015).…”

Protective Effect of Barberry ( Berberis vulgaris L.) Extract on Oxidative Stress and Behavioral Changes in Toxicity Induced by Diazinon in the Brain Tissue of Male Rats

“…Conversely, co-treatment with barberry extract led to an improvement in locomotor activity and anxiety levels in the animals. Our findings were consistent with those of Savy et al ( 2015 ) and Roegge et al ( 2008 ). They reported that chronic exposure to DZN can cause changes in the locomotor activity of animals depending on the duration and level of exposure.…”

Gene expression analysis reveals chronic low level exposure to the pesticide diazinon affects psychological disorders gene sets in the adult rat

“…We have previously reported that marble burying behaviour is a sensitive behavioural measure of low level OP exposure (Savy et al, 2015), and the current study supports this. Marble burying behaviour is frequently described as an ethological measure of anxiety in rodents and has been used to screen anxiolytic drugs in rodents (Broekkamp et al, 1986;Njung'e and Handley, 1991).…”

Sub-chronic exposure to diazinon induce cognitive impairment, alternations in amyloid precursor proteins, and TNF-α expression in the hippocampus of adult rats

“…The result obtained from the EPM and OFT tests illustrated that sub-chronic exposure to low-dose DZN increased anxiety-like behavior showed by decreased motor activity. These data were in line with previous ndings on the association of exposure with OPs and anxiogenesis (Baltazar et al 2014;Savy et al 2015).…”

Protective Effect of Barberry ( Berberis vulgaris L.) Extract on Oxidative Stress and Behavioral Changes in Toxicity Induced by Diazinon in the Brain Tissue of Male Rats

“…Conversely, co-treatment with barberry extract led to an improvement in locomotor activity and anxiety levels in the animals. Our findings were consistent with those of Savy et al ( 2015 ) and Roegge et al ( 2008 ). They reported that chronic exposure to DZN can cause changes in the locomotor activity of animals depending on the duration and level of exposure.…”

Gene expression analysis reveals chronic low level exposure to the pesticide diazinon affects psychological disorders gene sets in the adult rat

“…We have previously reported that marble burying behaviour is a sensitive behavioural measure of low level OP exposure (Savy et al, 2015), and the current study supports this. Marble burying behaviour is frequently described as an ethological measure of anxiety in rodents and has been used to screen anxiolytic drugs in rodents (Broekkamp et al, 1986;Njung'e and Handley, 1991).…”

Sub-chronic exposure to diazinon induce cognitive impairment, alternations in amyloid precursor proteins, and TNF-α expression in the hippocampus of adult rats

“…The result obtained from the EPM and OFT tests illustrated that sub-chronic exposure to low-dose DZN increased anxiety-like behavior showed by decreased motor activity. These data were in line with previous ndings on the association of exposure with OPs and anxiogenesis (Baltazar et al 2014;Savy et al 2015).…”

Protective Effect of Barberry ( Berberis vulgaris L.) Extract on Oxidative Stress and Behavioral Changes in Toxicity Induced by Diazinon in the Brain Tissue of Male Rats

“…Conversely, co-treatment with barberry extract led to an improvement in locomotor activity and anxiety levels in the animals. Our findings were consistent with those of Savy et al ( 2015 ) and Roegge et al ( 2008 ). They reported that chronic exposure to DZN can cause changes in the locomotor activity of animals depending on the duration and level of exposure.…”

Gene expression analysis reveals chronic low level exposure to the pesticide diazinon affects psychological disorders gene sets in the adult rat

“…We have previously reported that marble burying behaviour is a sensitive behavioural measure of low level OP exposure (Savy et al, 2015), and the current study supports this. Marble burying behaviour is frequently described as an ethological measure of anxiety in rodents and has been used to screen anxiolytic drugs in rodents (Broekkamp et al, 1986;Njung'e and Handley, 1991).…”