Effect of Sambong (Blumea balsamifera) Decoction on the Passive Avoidance Learning Behavior of Adult Zebrafish (Danio rerio): A Preliminary Study

Abstract

The medicinal plant Blumea balsamifera (L.) DC., locally known as sambong, is rich in polyphenols that exhibit nootropic and acetylcholinesterase inhibitory properties. These polyphenols make sambong a potential source of neuroprotective agents against cognitive disorders resulting from deficient acetylcholine signaling in the brain. The present study investigated the effect of sambong on adult zebrafish learning by directly exposing the animals in a sublethal sambong decoction. The anti-cholinergic drug atropine was used to impair learning performance in selected experimental groups. All four groups, namely, Control, Sambong, Atropine, and Sambong+atropine, were subjected to the passive avoidance learning test, wherein each fish was trained using an electroshock stimulus to avoid crossing toward the Dark compartment from the Light compartment of a shuttlebox. The change in fish crossing time (CFCT) in seconds, 24 hours after training, was measured as the index of learning. Results show that direct exposure to the sambong decoction significantly impaired learning in healthy zebrafish (p = 0.029). Furthermore, the sambong treatment appear to have no effect on the low CFCT of atropine-treated fish although an insufficient number of replicates prevented further statistical analysis. These observations suggest that exposure to sambong via direct immersion may be inappropriate for studying the nootropic property of the plant extract. With insufficient replicates tested and using only direct immersion as the mode of administration, the evidence from the present study is inconclusive to rule out the potential benefits of sambong on animal learning.