Sex differences in neuronal oscillatory activity and memory in the methylazoxymethanol acetate model of schizophrenia

Schizophr Res. 2024 May:267:451-461. doi: 10.1016/j.schres.2024.04.002. Epub 2024 Apr 20.

Abstract

The methylazoxymethanol acetate (MAM) rodent model is used to study aspects of schizophrenia. However, numerous studies that have employed this model have used only males, resulting in a dearth of knowledge on sex differences in brain function and behaviour. The purpose of this study was to determine whether differences exist between male and female MAM rats in neuronal oscillatory function within and between the prefrontal cortex (PFC), ventral hippocampus (vHIP) and thalamus, behaviour, and in proteins linked to schizophrenia neuropathology. We showed that female MAM animals exhibited region-specific alterations in theta power, elevated low and high gamma power in all regions, and elevated PFC-thalamus high gamma coherence. Male MAM rats had elevated beta and low gamma power in PFC, and elevated vHIP-thalamus coherence. MAM females displayed impaired reversal learning whereas MAM males showed impairments in spatial memory. Glycogen synthase kinase-3 (GSK-3) was altered in the thalamus, with female MAM rats displaying elevated GSK-3α phosphorylation. Male MAM rats showed higher expression and phosphorylation GSK-3α, and higher expression of GSK-β. Sex-specific changes in phosphorylated Tau levels were observed in a region-specific manner. These findings demonstrate there are notable sex differences in behaviour, oscillatory network function, and GSK-3 signaling in MAM rats, thus highlighting the importance of inclusion of both sexes when using this model to study schizophrenia.

Keywords: GSK-3; Learning and memory; Neuronal oscillations; Schizophrenia; Sex differences.

MeSH terms

  • Animals
  • Disease Models, Animal*
  • Female
  • Glycogen Synthase Kinase 3 / metabolism
  • Hippocampus / drug effects
  • Hippocampus / metabolism
  • Hippocampus / physiopathology
  • Male
  • Methylazoxymethanol Acetate* / pharmacology
  • Neurons / drug effects
  • Neurons / metabolism
  • Neurons / pathology
  • Neurons / physiology
  • Phosphorylation / drug effects
  • Prefrontal Cortex / drug effects
  • Prefrontal Cortex / metabolism
  • Prefrontal Cortex / physiopathology
  • Rats
  • Rats, Sprague-Dawley
  • Schizophrenia* / chemically induced
  • Schizophrenia* / metabolism
  • Schizophrenia* / physiopathology
  • Sex Characteristics*
  • Thalamus / drug effects
  • Thalamus / metabolism
  • Thalamus / physiopathology
  • tau Proteins / metabolism