Conifer Essential Oils Reversed Amyloid Beta1-42 Action by Modulating BDNF and ARC Expression in The Rat Hippocampus

Abstract

Background: The conifer species Pinus halepensis (Pinaceae) and Tetraclinis articulata (Cupressaceae) are widely used in traditional medicine due to their beneficial health properties. Objective: This study aimed to investigate the mechanisms by which P. halepensis and T. articulata essential oils (1% and 3%) could exhibit neuroprotective effects in an Alzheimer's disease (AD) rat model, induced by intracerebroventricular (i.c.v.) administration of amyloid beta1-42 (Aβ1-42). Method: The essential oils were administered by inhalation to the AD rat model, once daily, for 21 days. DNA fragmentation was assessed through a Cell Death Detection ELISA kit. Brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeleton-associated protein (ARC), and interleukin- 1β (IL-1β) gene expressions were determined by RT-qPCR analysis, while BDNF and ARC protein expressions were assessed using immunohistochemistry technique. Results: Our data showed that both essential oils substantially attenuated memory impairments, with P. halepensis mainly stimulating ARC expression and T. articulata mostly enhancing BDNF expression. Also, the inhalation of essential oils reduced IL-1β expression and induced positive effects against DNA fragmentation associated with Aβ1-42-induced toxicity, further contributing to the cognitive improvement in the rats with the AD-like model. Conclusion: Our findings provide further evidence that these essential oils and their chemical constituents could be natural agents of therapeutic interest against Aβ1-42-induced neurotoxicity.