Effects of Asenapine and Paliperidone on Depression, Anxiety and Analgesy in Mice: Alterations in Brain Neurotrophic Factors, Neurogenesis, and Blood Enzyme Levels

Schizophrenia, an important brain neurodevelopmental disorder, is observed in 1% of the global population. New-generation antipsychotics have been developed as alternatives to typical antipsychotics for more effective and safe therapy. Chronic administration of asenapine and paliperidone compared to haloperidol on depression, anxiety and analgesy in the forced swimming test (FST), elevated plus maze (EPM) and hot plate tests were examined in mice. Moreover effects of drugs, on expression levels of brain neurotrophic factors [brain-derived neurotrophic factor (BDNF), cAMP response element binding protein (CREB),nerve growth factor (NGF), synapsin and fibroblast growth factor 2 (FGF2)] in the hippocampus of mice, neurogenesis and neurodegeneration, and blood enzyme levels were also investigated. In FST, haloperidol (0.25 mg/kg) significantly increased immobility time while both asenapine (0.075 mg/kg) and paliperidone (0.25 and 0.50 mg/kg) significantly diminished this parameter. In EPM test, haloperidol significantly increased both % time spent in open arms and % open arm entries. Asenapine (0.075 mg/kg) and paliperidone (0.50 mg/kg) significantly increased % time spent in the open arms. They also increased % open arm entries, but this parameter failed to reach a statistically significant value. In hot plate test, haloperidol (0.125 and 0.25 mg/kg) and paliperidone (0.25 and 0.50 mg/kg) significantly increased the latency to lick the hind paws but asenapine had no effect. Asenapine and paliperidone upregulated more neurotrophic factors in the brain and caused less neurodegeneration compared to haloperidol. Investigated drugs had no effect on liver enzymes and plasma glucose levels. Asenapine and paliperidone may be preferred over classical antipsychotics since they have antidepressant-like effect, upregulate more neurotrophic factors and cause less neurodegeneration in naive mice without having diabetogenic and liver damaging effects. Paliperidone seems to possess superior effects compared to asenapine since it also exerts analgesic-like effect.