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KMID : 0606920230310040402
Biomolecules & Therapeutics
2023 Volume.31 No. 4 p.402 ~ p.410
5-Hydroxytryptophan Reduces Levodopa-Induced Dyskinesia via Regulating AKT/mTOR/S6K and CREB/¥ÄFosB Signals in a Mouse Model of Parkinson¡¯s Disease
Choi Yu-Jin

Huh Eu-Gene
Silvia Bettinelli
Kim Jin-Hee
Park Myoung-Gyu
Seo Seung-Yong
Kim Sun-Yeou
Oh Myung-Sook
Abstract
Long-term administration of levodopa (L-DOPA) to patients with Parkinson¡¯s disease (PD) commonly results in involuntary dyskinetic movements, as is known for L-DOPA-induced dyskinesia (LID). 5-Hydroxytryptophan (5-HTP) has recently been shown to alleviate LID; however, no biochemical alterations to aberrant excitatory conditions have been revealed yet. In the present study, we aimed to confirm its anti-dyskinetic effect and to discover the unknown molecular mechanisms of action of 5-HTP in LID. We made an LID-induced mouse model through chronic L-DOPA treatment to 6-hydroxydopamine-induced hemi-parkinsonian mice and then administered 5-HTP 60 mg/kg for 15 days orally to LID-induced mice. In addition, we performed behavioral tests and analyzed the histological alterations in the lesioned part of the striatum (ST). Our results showed that 5-HTP significantly suppressed all types of dyskinetic movements (axial, limb, orolingual and locomotive) and its effects were similar to those of amantadine, the only approved drug by Food and Drug Administration. Moreover, 5-HTP did not affect the efficacy of L-DOPA on PD motor manifestations. From a molecular perspective, 5-HTP treatment significantly decreased phosphorylated CREB and ¥ÄFosB expression, commonly known as downstream factors, increased in LID conditions. Furthermore, we found that the effects of 5-HTP were not mediated by dopamine1 receptor (D1)/DARPP32/ERK signaling, but regulated by AKT/mTOR/S6K signaling, which showed different mechanisms with amantadine in the denervated ST. Taken together, 5-HTP alleviates LID by regulating the hyperactivated striatal AKT/mTOR/S6K and CREB/¥ÄFosB signaling.
KEYWORD
Parkinson¡Çs disease, Levodopa, Levodopa-induced dyskinesia, 5-Hydroxytryptophan, Serotonin
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