A Stereological Study on Hippocampal Subfields Following Administration of Methamphetamine in Male Mice

This study examined sub-chronic effects of Methamphetamine (METH) on the stereological parameters in the Cornu Ammonis (CA) of the hippocampus in adult mice.
Fifteen adult male mice, eight weeks old, were randomly divided into three groups: receive saline (controls), or low-dose (LD) 2.5 mg/kg METH, or high-dose (HD) 25 mg/kg METH, via daily intraperitoneal administrations for one month. The Cavalieri principle was used to estimate the volume of CA hippocampal field. The physical disector was used to determine the numerical density of CA1 and CA3 pyramidal cells. The qualitative Golgi staining was also done for analyzing the dendritic morphology of CA1 and CA3 pyramidal cells.
Our results showed that in METH-treated mice, the volumes of the Oreins, Pyramidal and Radiatum-Lacunosum-Moleculare layers in the CA1 and CA3, the entire volumes of the CA1 and CA3 subfields and the entire hippocampal volume were significantly increased compared to the control animals (p˂0.001). The estimated total number and numerical density of pyramidal cells in the CA1 and CA3 in both treated groups showed a significant decrease in comparison with the controls (p˂0.001). The pyramidal neurons of CA1 and CA3 in treated mice had more dendritic arborization and greater dendritic length than control mice.
Our findings indicate that sub-chronic METH injection induces stereological changes in the structure of the hippocampus in adult mice. A neuroanatomical basis may be related to the primarily reported impairment of learning and memory abilities in the METH user.