Effect of Adipokinetic Hormone on Learning-Memory in a Scopolamine-Induced Alzheimer's Model in Mice

Neurosecretory cells of insects synthesize Adipokinetic Hormone (AKH). Previous studies indicated that AKH improves memory functions. This study aimed to explore the effects of AKH on learning and memory in an Alzheimer's disease model.

Morris Water Maze (MWM), Passive Avoidance (PA), and Modified Elevated Plus Maze (mEPM) tests were conducted in BALB/c mice. Initially, each group consisted of 8 to 9 animals; in total, 120 animals were used in this study. The groups included control, Ani-AKH (1 and 2 mg/kg), Lia-AKH (1 and 2 mg/kg), Pht-HrTH (1 and 2 mg/kg), Scopolamine (1 mg/kg), and Scopolamine combinations. Hormones were given for 6 days in the MWM test to evaluate learning and memory before the second trial in the PA test for memory assessment and after the first trial in the mEPM test to examine consolidation.

In the MWM test, Ani-AKH and Pht-HrTH reduced escape latency compared to the scopolamine group (p<0.05). During the probe trial, Ani-AKH increased time in the escape platform quadrant (p<0.5) and reversed scopolamine's effects (p<0.001). Lia-AKH and Pht-HrTh did not affect time in the quadrant but reversed scopolamine's effects (p<0.01). In the PA test, Ani- AKH reversed scopolamine's effects (p<0.5), while Lia-AKH did so in the mEPM test (p<0.01). The control group showed strong muscarinic receptor staining, while the scopolamine group did not. Ani-AKH and Lia-AKH showed moderate to strong receptor staining, indicating partial restoration.

AKH and its analogs may enhance memory function by modulating cholinergic pathways, particularly through the partial restoration of muscarinic receptor activity. These results underscore their potential as investigational therapeutics for neurodegenerative disorders characterized by cognitive decline.

Our study indicates that AKH may help reduce memory impairments, though the effects depend on the specific assessment methods used in the tests.