A histopathological comparison of prophylactic effects of Rosmarinic Acid and Oleanolic Acid isolated from Salvia species (sage) in scopolamine induced dementia model

Abstract

Objective: Alzheimer's disease (AD) is the most common form of dementia, can be created in experimental models by using toxins. Possible therapeutic effects of secondary metabolites Rosmarinic (RA) and Oleanolic acids (OA) obtained from Salvia species (sage) were investigated using histopathological and immunohistochemical tecniques in experimental Alzheimer's-like dementia model induced by scopolamine.
 Study Design: Male BALB/c mice (n: 48) of 3-4 weeks old, divided into 6 groups; control received only saline(i.p.) for 21 days, scopolamine group received 3 mg/kg of scopolamine (i.p.) between 8-21th days. Scopolamine + RA group received 5 mg/kg RA (i.p.) between days 0 and 21 and 3 mg/kg of scopolamine (i.p.) between 8-21th days. Scopolamine + OA group received 5 mg/kg of OA (i.p.) between days of 0-21 and 3 mg/kg of scopolamine (i.p.) between 8-21th days. RA group received 5 mg/kg RA (i.p.) between 0-21th days. OA group received 5 mg/kg of OA (i.p.) between 0-21th days. Animals were sacrificed under anesthesia, brain tissues were excised and placed in 10% formaldehyde, embedded in paraffin wax. 5 µm sections were cut, stained for histopathological examinations. Immunoreactivity for Beta-amyloid accumulation was observed. ImageJ 153 software was used to analyze IHC figures. Positive signaling for DAB density was calculated, ANOVA test with the post hoc dunnett's or tukey test were applied, p<0.05 was considered statistically significant.
 Results: In scopolamine+RA treated group, tissue degeneration was less compared to the scopolamine group. Scopolamine+OA group revealed signs of pyknosis in neurons. The amyloid beta immunoexpression was positive in scopolamine group partially positive in scopolamine+OA group but, negative in RA treated scopolamine group. Intensity of signal in scopolamine group was statistically increased compared to control (p=0.0102). Intensity of signal was reduced in Scopolamine+RA and Scopolamine+OA groups, was statistically significant (p=0.0281 and p=0.0362, respectively).
 Conclusion: We suggest that pretreatment of RA and OA decreased beta amyloid formation and ameliorated tissue structure but, further studies with different methods are needed to be commercially available.
 Keywords: Scopolamine, dementia, Rosmarinic acid, Oleanolic acid, histopathology, Amyloid beta