Like psychosis, like dementia: Nigella sativa oil enhanced olfactory and amygdalic phenotypes in socially isolated BALB/c mice model of schizophrenia

Abstract

AbstractBackgroundSocial isolation rearing (SIR) is a developmental schizophrenia model with characteristic behavioral symptoms like anxiety and olfactory deficits influenced by the amygdala and olfactory bulbs respectively. Psychiatric disorders and dementias are often comorbid, with neuropsychiatric disturbances constituting inherent component of Alzheimer’s. As long‐term side effects mar available antipsychotics, novel natural psycho‐dementia drugs are urgently needed. This study thus investigated Nigella sativa (NS) for its impacts on olfactory bulb and amygdalic phenotypes in socially isolated BALB/c mice.MethodFifty (50) male BALB/c mice weaned after 21 days of birth were grouped equally into five. CTRL and NS were reared socially and administered normal saline (1ml/kgbw) and Nigella sativa (1ml/kgbw) respectively. SIR‐NS, NS‐SIR and SIR were socially isolated and administered Nigella sativa (1ml/kgbw) post‐isolation, Nigella sativa pre‐isolation (through maternal exposure) and normal saline respectively. Respective administrations lasted 10 days while social isolation lasted 4 weeks. Amygdalic and olfactory bulb glutamate, GPX and dopamine levels as well as histo‐architecture were investigated in addition to body weights, relative brain weight, temperature, food and water consumption. Olfactory acuity was assayed with olfactory sensitivity and discrimination tests while anxiety levels were assayed with elevated plus maze. Statistical analysis was carried out using one‐way ANOVA at 95% CI.ResultIn addition to increased brain‐body weight ratios, Nigella sativa increased the glutamate and dopamine levels in the amygdala and olfactory bulb of socially isolated mice which were maternally exposed to Nigella sativa (NS‐SIR mice) compared to the untreated but isolated mice. GPX also increased in the amygdala of the NS‐SIR but not in the olfactory bulb. Maternal Nigella sativa exposure prevented olfactory insensitivity in the SIR mice but with no ameliorative effect on the open arm exploration time in the pre‐ or post‐treated mice compared with the untreated isolated mice. NS‐SIR animals exhibited better histoarchitecture than SIR mice, as evidenced by increased neuronal sizes, densities and neuro‐piliary staining.ConclusionSocial isolation modelled olfactory and partial emotional deficits in BALB/c mice similar to schizophrenics. Maternal exposure to Nigella sativa showed significant prophylactic potentials against these deficits especially in olfaction. However, farther isolation distance between the animals is recommended for better results.