Chemotherapy-induced cognitive impairment in
cancer patients is known as "
chemobrain".
Doxorubicin and
Cyclophosphamide are two chemotherapeutic agents used in combination to treat solid
tumors.
L-carnitine was reported for its
anti-oxidant and anti-inflammatory activities. The goal of the present study was to elucidate the
neuroprotective effect of
L-carnitine against
chemobrain induced by
Doxorubicin and
Cyclophosphamide in rats. Rats were divided into five groups: Control group;
Doxorubicin (4mg/kg, IV) and
Cyclophosphamide (40mg/kg, IV)-treated group; two
L-carnitine-treated groups (150 and 300mg/kg, ip) with
Doxorubicin and
Cyclophosphamide; and
L-carnitine alone-treated group (300mg/kg).
Doxorubicin and
Cyclophosphamide induced histopathological changes in rats' hippocampi and prefrontal cortices, as well as reduced memory as evidenced by behavioural testing.
L-carnitine treatment showed opposite effects. In addition,
chemotherapy treatment enhanced oxidative stress via reducing
catalase and
glutathione levels, and inducing lipid peroxidation. By contrast,
L-carnitine treatment showed powerful
antioxidant effects reversing
chemotherapy-induced oxidative damage. Moreover,
chemotherapy combination induced
inflammation via their effect on nuclear factor kappa B (p65), interleukin-1β, and
tumor necrosis factor-α. However,
L-carnitine treatment corrected such inflammatory responses. Furthermore,
Doxorubicin and
Cyclophosphamide reduced synaptic plasticity via hindering expression of
brain-derived neurotrophic factor, phosphorylated cyclase response element
binding protein,
synaptophysin, and
postsynaptic density protein 95 whereas
protein expression of such synaptic plasticity
biomarkers was enhanced by
L-carnitine treatment. Finally,
acetylcholinesterase activity was found to be enhanced by
chemotherapy treatment affecting rats' memory while
L-carnitine treatment reduced
acetylcholinesterase activity.
L-carnitine also showed hepatoprotective and renal protective effects suggesting liver/brain and kidney/brain axes as possible mechanisms for its
neuroprotective effects.