Mercury sulfide-containing Hua-Feng-Dan and 70W (Rannasangpei) protect against LPS plus MPTP-induced neurotoxicity and disturbance of gut microbiota in mice.

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE Mercury sulfides (HgS) are frequently included in Ayurveda, Tibetan and Chinese medicines to assist the presumed therapeutic effects, but the ethnopharmacology remains elusive. The present study examined the protective effects of α-HgS-containing Hua-Feng-Dan and ß-HgS-containing 70 Wei-Zhen-Zhu-Wan (70W, Rannasangpei) against Parkinson's disease mice induced by lipopolysaccharide (LPS) plus 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). METHOD: A single injection of LPS (5 mg/kg ip) was given to adult male C57BL/6 mice, and 150 days later, the low dose of MPTP (15 mg/kg, ip, for 4 days) was given to produce the "two-hit" Parkinson's disease model. Together with MPTP treatment, mice were fed with clinically-relevant doses of Hua-Feng-Dan (0.6 g/kg) and 70W (0.2 g/kg) for 35 days. Rotarod test was performed to examine muscle coordination capability. At the end of the experiment, brain was transcardially perfused with paraformaldehyde, the substantia nigra was sectioned for microglia (Iba1 staining) and dopaminergic neuron (THir staining) determination. Colon bacterial DNA was extracted and subjected to qPCR analysis with 16S rRNA probes. RESULTS: The low-grade, chronic neuroinflammation produced by LPS aggravated MPTP neurotoxicity, as evidenced by decreased motor activity, intensified microglia activation and loss of dopaminergic neurons. Both Hua-Feng-Dan and 70W increased rotarod activity and ameliorated the pathological lesions in the brain. In gut microbiomes examined, LPS plus MPTP increased Verrucomicrobiaceae, Methanobacteriaceae, Pronicromonosporaceae, and Clostridaceae species were attenuated by Hua-Feng-Dan and 70W. CONCLUSIONS: α-HgS-containing Hua-Feng-Dan and ß-HgS-containing 70W at clinical doses protected against chronic LPS plus MPTP-induced toxicity to the brain and gut, suggesting HgS-containing traditional medicines could target gut microbiota as a mechanism of their therapeutic effects.