Memory retrieval improvement by Ptychopetalum olacoides in young and aging mice

Abstract

Amazonian peoples use traditional remedies prepared with Ptychopetalum olacoides (PO) roots for treating various age-related conditions. This study shows that a single intraperitoneally (i.p.) administration of Ptychopetalum olacoides ethanol extract (POEE, 50 and 100 mg/kg) improved memory retrieval in step-down inhibitory avoidance (P ≤ 0.05 and P ≤ 0.01, test session latency 102 [19.38–300] and 192 [91.3–300] s, respectively versus control 24.7 [12.9–89.6]), without interfering with acquisition or consolidation in adult (2.5-month-old) mice. Comparable results were obtained with POEE given p.o. at 800 and 1000 mg/kg (P ≤ 0.05 and P ≤ 0.01, 52.7 [19.5–297.2] and 85.7 [44.4–260.4] versus control 20.5 [8–92.6]). Moreover, memory amelioration was also observed (P ≤ 0.01) in aging (14 months) mice presenting memory deficit (14.95 [10.8–41]) as compared to adult (2.5 months) mice (57 [15.7–141.2]), with the extract given acutely i.p. 100 mg/kg (300 [133.1–300] versus control 14.95 [10.8–41]) or p.o. 800 mg/kg (28.4 [15.1–84.6] versus control 11.5 [7.8–23.3]). Indeed, aging mice treated with POEE (800 mg/kg, p.o.) performed as well as adult mice. Consistently with its traditional use, the data suggest that POEE facilitates memory retrieval. Although the antioxidant and acetylcholinesterase inhibitory properties previously described for this extract may be of relevance, the molecular mechanism(s) underlying the improvement in memory retrieval here reported merit further scrutiny.