Scientists in China reported these findings in the study, “Neuroprotective effects of Tongtian oral liquid, a Traditional Chinese Medicine in the Parkinson’s disease-induced zebrafish model,” published in Biomedicine & Pharmacotherapy.

Tongtian oral liquid, also called Tongtian Koufuye or TTKFY, is thought to have antioxidant and neuroprotective effects. It contains 11 herbal constituents, among them tea, licorice, mint, and chrysanthemum.

In an initial set of experiments, the researchers treated larval zebrafish with varying doses of TTKFY. At low doses, the herbal therapy was well-tolerated by the fish. But doses of 8 ml/L caused developmental malformations, and higher doses (16 or 32 ml/L) were lethal to the developing fish.

The team then tested TTKFY in a zebrafish model, with Parkinson’s induced by exposing the fish to a toxic chemical called MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). Fish given MPTP had significantly smaller dopaminergic (dopamine-producing) neurons — consistent with Parkinson’s, which is caused by the death and dysfunction of these nerve cells. The fish also displayed Parkinson’s-like motor abnormalities, such as a slower swimming speed.

“MPTP-induced Parkinsonism is a well-accepted and currently, the most appropriate model to study [Parkinson’s],” the researchers wrote.

Treatment with TTKFY, at doses of 2 or 4 ml/L, allowed for growth to return to dopamine-producing neurons and also improved locomotion in the fish (swimming speed and distance).

“These findings suggest that MPTP-induced locomotor aberration can be rescued by higher doses of TTKFY in zebrafish larvae,” the researchers wrote. However, they added that even with TTKFY treatment, motor behavior in the Parkinson’s fish model “did not reach the … level” of healthy zebrafish included as a control group.

Further analyses indicated that treatment with TTKFY reduced the oxidative stress — a type of cell damage caused by highly reactive oxygen-containing molecules that’s characteristic of Parkinson’s — brought on by MPTP. The herbal combination also normalized changes in the expression of several dopamine-related genes that were dysregulated by MPTP. (Gene expression is the process by which information in a gene is synthesized to create a protein.)

“All these results collectively provide ample evidence pertaining to the neuroprotective ability of TTKFY in MPTP-induced neurotoxicity in the zebrafish model of [Parkinson’s],” the scientists concluded.

“Further studies are necessary to manifest the exact mechanism of action of TTKFY on neuroprotection in MPTP-induced experimental Parkinsonism in the zebrafish model,” they added.