Background: Experimental evidences in vitro and in vivo highlight the favourable neuropharmacological profile of bergamot essential oil (BEO), a phytocomplex obtained by cold pressing of the epicarp and partly of the mesocarp of Citrus bergamia Risso et Poiteau (Rutaceae family, genus Citrus). In fact, BEO strengthens synaptic transmission (1), facilitates higher frequency bands of the electrocorticographic (ECoG) spectrum (2) and it shows neuroprotective (3-5) and analgesic properties (6-9). Likewise other essential oils, BEO is widely used in aromatherapy, a branch of herbal medicine, to relieve symptoms of stress-induced anxiety (10) though limited preclinical data are, actually, available. Accordingly, here we investigate the effects of the essential oil in behavioural tests in rats. The results yielded show that BEO is endowed with properties distinct from typical anxiolytic benzodiazepines, such as diazepam (DZP). Materials and methods: The anxiolytic effect of BEO administered intraperitoneally (i.p.) was studied in rats using an open field task (OFT), an elevated plus-maze task (EPM) and a forced swimming task (FST). Jojoba oil is used as vehicle (control) of BEO. Results: Systemic administration of BEO (250 or 500 μl/kg i.p.; n=9 and n=12 rats per group, respectively) induces in the OFT a significant (p<0.0001) decrease in the frequencies of crossing, rearing and wallrearing versus the control group (n=12 rats). Conversely, the anxiolytic dose of DZP (1.2 mg/kg i.p., n=6 rats) does not induce statistically significant changes (p>0.05) in these parameters compared to control. A statistically significant decrease is also observed for grooming behaviour in the animals treated both with BEO or DZP compared to vehicle group, while immobility is increased in the rats treated with the phytocomplex. Interestingly, at variance with the effects of BEO, the animals treated with the sedative dose of DZP (5 mg/kg, n=5) are not vigilant and active in all OFT sessions. In EPM task, the administration of BEO or the anxiolytic dose of DZP (n=9) induces a trend towards an increase of the time spent in open arms when compared to vehicle group (n=5). The rats treated with the higher dose of BEO (n=5) or the sedative dose of DZP (n=5) show a decrease in both arm entries when compared to control (n=5). Interestingly, at variance with the effects of the sedative dose of DZP, the animals treated with the higher dose of BEO are still vigilant and active. In FST task, a trend towards a decrease in swimming is observed after both treatments compared to control (n=10), whereas statistical analysis indicates a significant increase (p<0.05) in immobility behaviour in rats treated with BEO (n=6) versus the anxiolytic dose of DZP (n=5). Conversely, drowning-recovering frequency is significantly increased in DZP treated rats when compared to jojoba oil or BEO groups. No statistically significant difference (p>0.05) is observed in struggling behaviour. Conclusions: In conclusion, BEO induces relaxant and anxiolytic effects with a behavioural pattern distinct from that of DZP. At variance with the effects of sedative dose of DZP, rats treated with BEO are vigilant throughout the duration of the tests and this deserves further investigation. Altogether, our results support the rational use of bergamot essential oil in aromatherapy in symptoms of stress-induced anxiety and are of particular interest since psychotropic drugs, like benzodiazepines, are often associated with severe side effects that adversely affect patient compliance. Benzodiazepines are also widely used to control disruptive behaviour and sleep disturbances, clustered as behavioural and psychological symptoms of dementia (BPSDs), in patients with dementia though limited evidence exists for their clinical efficacy and safety (11-12). Incidentally, aromatherapy has recently received great interest in the complementary treatment of BPSDs and randomized clinical trials lend some support this use (10).
Distinct Anxiolytic Profile Of Bergamot Essential Oil In Preclinical Behavioural Studies
ROMBOLA', Laura;Bagetta G;Morrone LA
2017-01-01
Abstract
Background: Experimental evidences in vitro and in vivo highlight the favourable neuropharmacological profile of bergamot essential oil (BEO), a phytocomplex obtained by cold pressing of the epicarp and partly of the mesocarp of Citrus bergamia Risso et Poiteau (Rutaceae family, genus Citrus). In fact, BEO strengthens synaptic transmission (1), facilitates higher frequency bands of the electrocorticographic (ECoG) spectrum (2) and it shows neuroprotective (3-5) and analgesic properties (6-9). Likewise other essential oils, BEO is widely used in aromatherapy, a branch of herbal medicine, to relieve symptoms of stress-induced anxiety (10) though limited preclinical data are, actually, available. Accordingly, here we investigate the effects of the essential oil in behavioural tests in rats. The results yielded show that BEO is endowed with properties distinct from typical anxiolytic benzodiazepines, such as diazepam (DZP). Materials and methods: The anxiolytic effect of BEO administered intraperitoneally (i.p.) was studied in rats using an open field task (OFT), an elevated plus-maze task (EPM) and a forced swimming task (FST). Jojoba oil is used as vehicle (control) of BEO. Results: Systemic administration of BEO (250 or 500 μl/kg i.p.; n=9 and n=12 rats per group, respectively) induces in the OFT a significant (p<0.0001) decrease in the frequencies of crossing, rearing and wallrearing versus the control group (n=12 rats). Conversely, the anxiolytic dose of DZP (1.2 mg/kg i.p., n=6 rats) does not induce statistically significant changes (p>0.05) in these parameters compared to control. A statistically significant decrease is also observed for grooming behaviour in the animals treated both with BEO or DZP compared to vehicle group, while immobility is increased in the rats treated with the phytocomplex. Interestingly, at variance with the effects of BEO, the animals treated with the sedative dose of DZP (5 mg/kg, n=5) are not vigilant and active in all OFT sessions. In EPM task, the administration of BEO or the anxiolytic dose of DZP (n=9) induces a trend towards an increase of the time spent in open arms when compared to vehicle group (n=5). The rats treated with the higher dose of BEO (n=5) or the sedative dose of DZP (n=5) show a decrease in both arm entries when compared to control (n=5). Interestingly, at variance with the effects of the sedative dose of DZP, the animals treated with the higher dose of BEO are still vigilant and active. In FST task, a trend towards a decrease in swimming is observed after both treatments compared to control (n=10), whereas statistical analysis indicates a significant increase (p<0.05) in immobility behaviour in rats treated with BEO (n=6) versus the anxiolytic dose of DZP (n=5). Conversely, drowning-recovering frequency is significantly increased in DZP treated rats when compared to jojoba oil or BEO groups. No statistically significant difference (p>0.05) is observed in struggling behaviour. Conclusions: In conclusion, BEO induces relaxant and anxiolytic effects with a behavioural pattern distinct from that of DZP. At variance with the effects of sedative dose of DZP, rats treated with BEO are vigilant throughout the duration of the tests and this deserves further investigation. Altogether, our results support the rational use of bergamot essential oil in aromatherapy in symptoms of stress-induced anxiety and are of particular interest since psychotropic drugs, like benzodiazepines, are often associated with severe side effects that adversely affect patient compliance. Benzodiazepines are also widely used to control disruptive behaviour and sleep disturbances, clustered as behavioural and psychological symptoms of dementia (BPSDs), in patients with dementia though limited evidence exists for their clinical efficacy and safety (11-12). Incidentally, aromatherapy has recently received great interest in the complementary treatment of BPSDs and randomized clinical trials lend some support this use (10).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
