Inhaled Litsea glaucescens K. (Lauraceae) leaves' essential oil has anxiolytic and antidepressant-like activity in mice by BDNF pathway activation.

ETHNOPHARMACOLOGICAL RELEVANCE: Litsea glaucescens K. (Lauraceae) is a small tree from the Mexican and Central American temperate forests, named as "Laurel". Its aromatic leaves are ordinarily consumed as condiments, but also are important in Mexican Traditional Medicine, and among the most important non wood forest products in this area. The leaves are currently used in a decoction for the relief of sadness by the Mazahua ethnic group. Interestingly, "Laurel" has a long history. It was named as "Ehecapahtli" (wind medicine) in pre-Columbian times and applied to heal maladies correlated to the Central Nervous System, among them depression, according to botanical texts written in the American Continent almost five centuries ago. AIM OF THE STUDY: Depression is the first cause of incapacity in the world, and society demands alternative treatments, including aromatherapy. We have previously demonstrated the antidepressant-like activity of L. glaucescens leaves' essential oil (LEO), as well as their monoterpenes linalool, and beta-pinene by intraperitoneal route in a mice behavioral model. Here we now examined if LEO and linalool exhibit this property and anxiolytic activity when administered to mice by inhalation. We also investigated if these effects occur by BDNF pathway activation in the brain. MATERIALS AND METHODS: The LEO was prepared by distillation with water steam and analyzed by gas chromatography-mass spectrometry (GC-MS). The monoterpenes linalool, eucalyptol and ß-pinene were identified and quantified. Antidepressant type properties were determined with the Forced Swim Test (FST) on mice previously exposed to LEO or linalool in an inhalation chamber. The spontaneous locomotor activity and the sedative effect were assessed with the Open Field Test (OFT), and the Exploratory Cylinder (EC), respectively. The anxiolytic properties were investigated with the Elevated Plus Maze Apparatus (EPM) and the Hole Board Test (HBT). All experiments were video documented. The mice were subjected to euthanasia, and the brain hippocampus and prefrontal cortex were dissected. RESULTS: The L. glaucescens essential oil (LEO) contains 31 compounds according to GC/MS, including eucalyptol, linalool and beta-pinene. The LEO has anxiolytic effect by inhalation in mice, as well as linalool, and ß-pinene, as indicated by OFT and EC tests. The LEO and imipramine have antidepressant like activity in mice as revealed by the FST; however, linalool and ketamine treatments didn't modify the time of immobility. The BDNF was increased in FST in mice treated with LEO in both areas of the brain as revealed by Western blot; but did not decrease the level of corticosterone in plasma. The OFT indicated that LEO and imipramine didn't reduce the spontaneous motor activity, while linalool and ketamine caused a significant decrease. CONCLUSION: Here we report by the first time that L. glaucescens leaves essential oil has anxiolytic effect by inhalation in mice, as well as linalool, and ß-pinene. This oil also maintains its antidepressant-like activity by this administration way, similarly to the previously determined intraperitoneally. Since inhalation is a common administration route for humans, our results suggest L. glaucescens essential oil deserve future investigation due to its potential application in aromatherapy.

Orchiectomy modifies the antidepressant-like response of nicotine in the forced swimming test.

Several studies have demonstrated that nicotine (NIC) exhibits antidepressant-like effects. In addition, it has been suggested that sexual hormones participate in the antidepressant actions of antidepressives. The present study was designed to analyze the effect of orchiectomy and the supplementation of testosterone propionate (TP) or 17ß-estradiol (E(2)) on the antidepressant properties of NIC using the forced swimming test (FST), as well as to determine possible changes in the FST during different time periods after orchiectomy. In order to evaluate the influences of orchiectomy on the effects of NIC, the study first evaluated the effects of different time periods on orchiectomized rats (15, 21, 30, 45 and 60 days) that were subjected to the FST. Then, different doses of NIC (0.2, 0.4, 0.8, 1.6 mg/kg, sc) were administered for 14 days to both intact and orchiectomized rats (after 21 day) which were then also subjected to the FST. Finally, the influence of the TP or E(2) supplementation on the antidepressant-like effect of NIC on orchiectomized rats (after 21 days) was also analyzed. Results reveal that orchiectomy significantly increased immobility behavior and decreased swimming and climbing up to 60 days after castration. In contrast, NIC decreased immobility behavior and increased swimming in intact rats; whereas orchiectomy suppressed this antidepressant effect of NIC. Only with E(2) supplementation was it possible to restore the sensitivity of the castrated rats to NIC. These results suggest that E(2) was able to facilitate the antidepressant response of NIC in orchiectomized rats.