Cognitive and histopathological effects of olive leaf extract in colchicine-induced hippocampal neurodegeneration in rats

Olive leaf extract (OLE) has robust anti-oxidant and anti-inflammatory properties. A toxic dose of colchicine (COL) injected into the hippocampus disrupts the microtubules’ neuronal structure causing it to be unstable and depolymerized. The objective of the current study was to evaluate the protective effects of OLE treatment on the CA1 hippocampal pyramidal cells of rats that are injected with intracranial COL.

Eighteen rats were divided into control, COL-injected, and OLE-treated-colchicine-injected (COL+OLE) groups (n = 6). A vehicle solution was injected into the hippocampi of the control rats, whereas 15 μg/5 μL of COL was injected into the hippocampi of COL and COL+OLE groups. Forced oral treatment with 100 mg/kg OLE was commenced a week later and continued for 15 days. Short-term memory (STM) test using the Morris water maze (MWM) was performed followed by the retention probe memory test. Hippocampal samples from animals of all groups were collected for histopathological examination and qualitative assessment of the viable pyramidal cells at the CA1 hippocampal region.

The control and COL+OLE groups demonstrated significantly better performance (P < 0.05) in the STM test and its subsequent retention probe memory test as compared to the COL group. The morphology of the pyramidal cells of the COL+OLE treated rats was preserved, showing less distortion than the COL group.

OLE treatment led to a considerable preservation in the STM function of rats challenged with intrahippocampal COL injection. This memory improvement of the OLE might be attributed to its promising neuroprotective potential on hippocampal pyramidal cells.