Biological & pharmaceutical bulletin
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The present study was designed to evaluate central inhibitory effects of the essential oil from Acori graminei Rhizoma (AGR), the dry rhizomes of Acorus gramineus SOLANDER (Araceae) upon fragrance inhalation (aroma therapy). Preinhalation of the oil markedly delayed the appearance of pentylenetetrazole-induced convulsion. Furthermore, inhalation impressively inhibited the activity of gamma-aminobutyric acid (GABA) transaminase, a degrading enzyme for GABA as the inhalation period was lengthened. ⋯ Ten hour inhalation corresponded almost to the effect (145% increase) of oral administration (60 mg/kg). This sedative effect after inhalation or oral administration of AGR essential oil suggests that this oil may act on the CNS via the GABAergic system. The inhibitory activity of preinhalation of the essential oil on lipid peroxidation, to which the anticonvulsive action is attributed, also supported the above results, confirming and amplifying our previous reports on the CNS inhibitory effects of AGR.