Protective effect of Lavandula angustifolia essential oil inhalation on neuromodulators regulating the sleep/wake cycle in rats with total sleep deprivation.

Objectives: This study aimed to investigate the potential effects of different doses of Lavender angustifolia essential oil (Lavender EO) administered by inhalation on sleep latency and neuromodulators regulating the sleep/wake cycle in rats with total sleep deprivation (TSD).

Materials and methods: Forty-eight male Sprague-Dawley rats were divided into five groups: Control, Alprazolam (ALP, 0.25 mg/kg given intraperitoneally), L1 (Lavender EO, 0.3 ml given by inhalation), L2 (Lavender EO, 0.5 ml given by inhalation), and L3 (Lavender EO, 1 ml given by inhalation); TSD was applied to all groups. Rats in SD groups were kept on a platform surrounded by water for 18 hr for 20 days, and for the remaining time, the animals were exposed to Lavender EO for 1 hr (11:00-12:00) and then were kept in their home cage for 5 hr (12:00-17:00). Their brain and brainstem were removed for histopathological and immunohistochemical analyses (c-Fos, ChAT, GAD, and ADRB2 expression) in the locus coeruleus (LC), basal forebrain (BF), and preoptic area (PO).

Results: The groups ranked by the severity of edema, hyperemia, and neurodegeneration in LC, BF, and PO areas were control, L3, L1, L2, and ALP. c-Fos expression significantly decreased in all brain regions in all groups except the L1 group. ChAT and GAD expressions increased dramatically in all brain regions. ADRB2 significantly increased in LC in ALP and L2 groups; in the PO area in ALP, L1, and L2 groups; and in BF in all groups.

Conclusion: Lavender EO treatment ameliorated c-Fos, ChAT, GAD, and ADRB2 expression, similar to the effect of ALP.