Exploring the antidepressant potential of <i>Ruta chalepensis</i> essential oil in socially isolated rats: Behavioural and neurochemical insights

Depression is a psychiatric disorder that affects people globally, harming overall health. This study assessed the antidepressant effects of ruta oil (RO), obtained from Ruta chalepensis, using a depression model induced by social isolation (SI) for 30 days. Rats were divided into the following groups: normal control (4 rats per cage), RO control (400 mg/kg, 4 rats per cage), SI model (one rat per cage), SI+RO (200 mg/kg), SI+RO (400 mg/kg) and SI+fluoxetine (standard anti-depressant drug, 200 mg/kg). Behavioural alterations in rats were examined using the forced swim test (FST), open field test (OFT), and the sucrose preference test. Levels of lipid peroxidation, dopamine (DOP) and serotonin (SER), as well as the brain-derived neurotrophic factor (BDNF) levels in the hippocampus were quantified using enzyme-linked immunosorbent assay. Histological examination was performed using hematoxylin and eosin. SI results in the following behavior changes; suppressed locomotor activity (reflected by a decreased number of crossings in the OFT and an increase in immobility time in the FST), reduced exploratory behavior (indicated by a decreased frequency of rearing in OFT) and anhedonia (indicated by decreased sucrose preference). The hippocampal levels of DOP, SER, and BDNF levels were attenuated, while lipid peroxidation was elevated in socially isolated rats. In addition, histological examination revealed shrunken and dead pyramidal neurons and degenerated granular neurons in the granule cell layer of the hippocampus. Treatment with RO at both doses significantly attenuated the behavioural changes, biochemical alterations and neuronal damage induced by SI. In conclusion, RO effectively alleviated depression by enhancing the levels of neurotransmitters and BDNF, while reducing lipid peroxidation in the hippocampal tissues of rats. This study confirms that RO can serve as a reliable source of safe, plant-derived treatment and a powerful remedy for neurological disorders, either on its own or in combination with other medications.