146 Plasma and whole brain cholinesterase activities Ashraf S. Alias, Muna H. I. Al-Zubaidy, Yaareb J. Mousa, Fouad K. Mohammad Table 1. Plasma and whole brain cholinesterase activities (Δ pH/30 minutes) of apparently healthy quail (Coturnix coturnix), collard dove (Streptopelia decaocto) and rock dove (Columba livia gaddi) in Mosul, Iraq. Bird species Quail Collard dove Rock dove Plasma 0.96 ± 0.026 a 0.97 ± 0.031 a 1.44 ± 0.011 b Whole brain 0.29 ± 0.023 a* 0.82 ± 0.046 b* 1.42 ± 0.064 c Values are mean ± SE of 8 birds/species. Mean values within a column with different letters are significantly different from each other at p<0.05. * Sig- nificantly different from the corresponding plasma cholinesterase activity, p<0.05. Table 2. In vitro inhibition of plasma and whole brain cholinesterase (ChE) activities (Δ pH/30 minutes) in wild birds by dichlorvos, mala- thion, monocrotophos and carbaryl. Conc. % (μM) Plasma ChE inhib. Whole brain ChE % inhib. Insecticide Quail Control Dichlorvos Malathion Monocrotophos Carbaryl Collard dove Control Dichlorvos Malathion Monocrotophos Carbaryl Rock dove Control Dichlorvos Malathion Monocrotophos Carbaryl 0 0.5 1.0 0.5 1.0 0.5 1.0 5 10 0 0.5 1.0 0.5 1.0 0.5 1.0 5 10 0 0.5 1.0 0.5 1.0 0.5 1.0 5 10 0.96 ± 0.026 0.03 ± 0.014* 0.0 ± 0.0* 0.75 ± 0.056* 0.73 ± 0.056* 0.87 ± 0.034* 0.36 ± 0.020*a 0.35 ± 0.020* 0.27 ± 0.010*a 0.97 ± 0.031 0.09 ± 0.009* 0.11 ± 0.005* 0.88 ± 0.076* 0.79 ± 0.013*a 0.70 ± 0.005* 0.37 ± 0.025*a 0.60 ± 0.023* 0.57 ± 0.013*a 1.44 ± 0.011 0.04 ± 0.009* 0.02 ± 0.003* 0.62 ± 0.023* 0.47 ± 0.009*a 1.27 ± 0.036* 1.09 ± 0.008*a 1.26 ± 0.013* 0.90 ± 0.008*a 97 100 22 24 9 63 64 72 89 87 9 18 28 62 38 41 97 99 57 67 12 24 13 38 0.29 ± 0.023 0.09 ± 0.014* 0.04 ± 0.004*a 0.08 ± 0.009* 0.10 ± 0.025*a 0.07 ± 0.009* 0.23 ± 0.024*a 0.08 ± 0.008* 0.03 ± 0.005*a 0.82 ± 0.046 0.05 ± 0.009* 0.04 ± 0.004* 0.53 ± 0.009* 0.45 ± 0.055*a 0.54 ± 0.011* 0.48 ± 0.017*a 0.21 ± 0.019* 0.13 ± 0.011*a 1.42 ± 0.064 0.11 ± 0.021* 0.03 ± 0.004* 0.18 ± 0.028* 0.13 ± 0.013* 0.19 ± 0.021* 0.13 ± 0.011* 0.16 ± 0.010* 0.05 ± 0.003*a 69 86 72 66 76 21 72 90 95 96 35 45 34 41 74 84 92 98 87 91 87 91 89 96 n = 8 birds/ concentration group. * Significantly different from the respective control (0 concentration), p<0.05. a Significantly different from the respective lower concentration group of the insecticide, p<0.05. ISSN: 1337-6853 (print version) | 1337-9569 (electronic version) dove and quail (Table 1). The plasma cholinesterase activity of the rock dove was significantly (p<0.05) higher than those of the other two species (Table 1). Those of the whole brain, in statistically significant descending order, were observed in the rock dove, collard dove and quail (Table 1). In the quail and collard dove, plasma cholin- esterase activities were significantly higher than those of the whole brain (Table 1). In the rock dove, the difference between plasma and whole brain cholinesterase activities did not attain statistical significance level (p>0.05). There were no significant gender differences in plasma and whole brain cholinesterase activities of the birds. Using the technique of in vitro cholinesterase inhibition for 10 minutes, the insecticides dichlorvos, malathion, monocrotophos and carbaryl variably and significantly inhibited plasma (9–100%) and whole brain (21–98%) cholinesterase activities (Table 2). Among the insecticides, dichlorvos caused the highest percentage of cholinesterase inhibition in the plasma of the quail (100%) and the whole brain of the rock dove (98%), (Table 2). Discussion The present findings further support and add to previ- ously published findings from our lab on wild bird cholin- esterase in Mosul, Iraq (Alias & Mohammad, 2005). The method we used for measurement of plasma and whole brain cholinesterase activities is an electrometric one validated for use in mammals (Mohammad, 2007) and avian species (Abass & Mohammad, 2004; Mohammad & Al-Baggou, 2005; Al-Badrany & Mohammad, 2007; Mohammad et al., 2008). Determination of plasma or serum and brain cholinesterase activities in wild birds is used as a biomarker of exposure to widely used agri- cultural insecticides, organophosphates and carbamates (Burn & Leighton, 1996; Iko et al., 2003; Osten et al., 2005). It is also a major tool for diagnosing organophos- phate and carbamate poisoning in birds. It is therefore important to measure wild bird cholinesterase activities periodically to assess any environmental contamination by insecticides (Hooper, 1988; Cairns et al., 1991; Fossi et al., 1992; Wilson & Henderson, 1992; McInnes et al., 1996; Iko et al., 2003; Fildes et al., 2009). The present electrometric technique for measurement of cholines- terase activity was used to assess poisoning induced by organophosphate and carbamate insecticides in chickens (Abass & Mohammad, 2004; Mohammad & Al-Baggou, 2005; Al-Badrany & Mohammad, 2007; Mohammad et al., 2008) and to estimate the level of total and true cholinesterase activity in the plasma of wild birds (Alias & Mohammad, 2005). True cholinesterase activity in the plasma of wild birds is usually higher than that of mammals (Wilson et al., 1998; Wilson, 1999; Alias & Mohammad, 2005; Mohammad et al., 2007b). It might be differentially inhibited by organophosphate or carbamate pesticides (Osweiler et al., 1985; Osweiler, 1996; Wilson et al., 1998; Wilson, 1999; 2005). Therefore, measuring plasma (or serum) cholinesterase activity in wild birds