Investigation of the effect of atropine sulphate on the fenthion-induced injury in the rat hippocampus by stereological and morphometric methods

Organophosphates, which are toxic compounds used extensively as insecticides in agriculture, frequently cause intoxications both in our country and in the world. In addition to the acute and delayed symptoms of intoxication neuropsychiatric disorders such as confusion, lethargy, anxiety, depression, attention deficits, impaired motor steadiness and dexterity. Hippocampal functions related to memory, learning and emotions are well known. The aim of our study was to investigate the toxic effect of fenthion on pyramidal neurons in CA area of hippocampus using stereologic methods and light microscopy and to determine whether atropine has protective effect or not.Eighteen male adult Wistar albino rats weighing 200-250 g were used. Rats were divided into three groups, namely Control, Fenthion and Fenthion+Atropin. Control group received a single dose of 0,8 g/kg subcutaneous saline followed by 2 mg/kg/h saline intraperitoneally for four hours. Fenthion group received single dose of 0,8 g/kg subcutaneous fenthion followed by 2 mg/kg/h saline intraperitoneally for four hours. Fenthion+Atropin group received a single dose of 0,8 g/kg subcutaneous saline followed by 2 mg/kg/h atropin intraperitoneally for four hours. On the fifth day animals were sacrified using cardiac perfusion method and brains were removed. Right hemispheres were embedded in paraffin; sequential sections were obtained and stained with Cresyl Fast Violet. The optical disector/fractionator sampling method was used to estimate total neuronal number in hippocampus CA region. Area, circumference and radius of neurons were measured.Pyramidal cell number was found to be 620 803±30 818, 459 291±47 077 and 551328±51 710 in Control group, Fenthion group and Fenthion+Atropin group, respectively. These differences among the groups were statistically significant (p<0,05).In the Control group area, circumference and radius of neurons were 103 151±18 219 µm2; 1 272±98,67 µm ve 179,5±15,41 µm, respectively. In the Fenthion group area, circumference and radius of neurons were 264284±35 144 µm2; 1977±133,3 µm ve 286,5±20,77 µm, respectively. These increases in the Fenthion group were statistically significant (for all of the three parameters p=0.000). In the Fenthion+Atropin group area, circumference and radius of neurons were 98682±15091 µm2; 1219±92,75 µm ve 175,3±15,12 µm, respectively. Compared to Fenthion group, a statistically significant decrease was observed in all of the three parameters. There was no statistically significant difference between parameters of Fenthion+Atropin group and Control group.Swelling, pyknosis and karyolysis were observed in the cytoplasm of cells in hippocampus CA area in Fenthion group. Swelling of the cells caused an increase in area, circumference and radius of neurons. While there was no significant neuronal surface area, circumference and radius changes in hippocampus CA area in Fenthion+Atropin group, pyknosis was seen in the same group.Fenthion significantly reduces total pyramidal neuronal number in hippocampus CA area, increases apoptosis, causes neuronal swelling and increase in area, circumference and radius of neurons. Toxic effects of fenthion can be reduced completely or partly by atropin. Atropin has protective effects on the neurotoxicity caused by fenthion