Protective effects of aqueous extract of silybum marianum in 6-hydroxydopamine-induced model of parkinsonism in male rat: a behavioral, biochemical and histological study

Parkinson,s disease (PD) is a common neurological disorder due to degeneration of substantia nigra pars compacta degeneration. With regard to protective effect of silybum marianum, this study was conducted to evaluate the protective effect of aqueous extract of this plant in an experimental model of PD. Forty male rats were randomly divided into 4 groups; sham-operated(SH), extract-treated sham-operated (E+SH), lesion (L) and extract-treated lesion(E+L) groups. The hemi-PD model was induced by unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA, 12.5  g/  l of saline-ascorbate).The E+SH and E+L groups received intra-peritoneal pretreatment of aqueous extract of silybummarianum (200mg/kg/daily) for one week before surgery. Two weeks after surgery, the animals were tested for rotational behavior by apomorphine hydrochloride and the number of nissle-stained neurons in the substantia nigra pars compacta (SNC). Two weeks after surgery, apomorphine caused a significant contralateral turning (P<0.0001) and reduction in the number of neurons on the left side of the SNC in the L group in comparison with SH group (P<0.05). Administration of aqueous extract of silybum marianum decreased the rotational behavior in lesioned rats and attenuated the reduction of number of SNC neurons (P<0.05). On the other hand, treatment of SH group with extract of silybum marianum had no significant effect on the number of apomophine-induced rotation and neurons of SNC. Our finding shows in experimental model of PD, intra-peritoneal administration of aqueous extract of silybum marianum has protective effects against 6-OHDA toxicity.