Tanshinol protects hippocampus and attenuates vascular dementia development

Tanshinol suppresses cardiac allograft rejection in a murine model

BACKGROUND

Achieving long-term cardiac allograft survival without continuous immunosuppression is highly desired in organ transplantation. Studies have shown that Salvia miltiorrhiza, an herb also known as danshen, improves microcirculation and is highly effective in treating coronary heart disease. Our objective is to determine whether tanshinol, an ingredient of danshen, improves cardiac allograft survival.

METHODS

Fully vascularized heterotopic heart transplantation was performed using BALB/c mice as donors and C57BL/6 mice as recipients, which were then treated with tanshinol and rapamycin. CD4⁺FoxP3⁺ regulatory T cells (Tregs) were quantified by flow analyses, whereas CCL22 was measured by real-time polymerase chain reaction and Western blotting.

RESULTS

We found that tanshinol significantly delayed cardiac allograft rejection. It promoted long-term allograft survival induced by rapamycin, a mammalian target-of-rapamycin (mTOR) inhibitor. Tanshinol increased CD4⁺FoxP3⁺ Treg numbers in cardiac allografts, but not spleens and lymph nodes, of recipient mice by enhancing chemokine CCL22 expression in cardiac allografts, especially cardiac dendritic cells. In contrast, rapamycin increased Treg numbers in both lymphoid organs and allografts, suggesting that it generally expands Tregs. Moreover, Tregs induced by rapamycin plus tanshinol were more potent in suppressing T-cell proliferation in vitro than those from untreated recipients. Neutralizing CCL22 hindered CD4⁺FoxP3⁺ Treg migration to cardiac allografts and reversed long-term allograft survival induced by tanshinol plus rapamycin.

CONCLUSIONS

Tanshinol suppresses cardiac allograft rejection by recruiting CD4⁺FoxP3⁺ Tregs to the graft, whereas rapamycin does so via expanding the Tregs. Thus, tanshinol cooperates with rapamycin to further extend cardiac allograft survival.

Paeoniflorin improves regional cerebral blood flow and suppresses inflammatory factors in the hippocampus of rats with vascular dementia

OBJECTIVE

To explore the delayed neuroprotection induced by paeoniflorin (PF), the principal component of Paeoniae radix prescribed in Chinese medicine, and its underlying mechanisms in rats subjected to vascular dementia (VD).

METHODS

A rat model of VD was induced by bilateral common carotid arteries occlusion (BCCAO). Low-dose or high-dose PF (20 or 40 mg/kg once per day) was administrated for 28 days after VD. The behavioral analysis of rat was measured by water morris. Regional cerebral blood volume (rCBV), regional cerebral blood flflow (rCBF) and mean transit time (MTT) were measured in the bilateral hippocampus by perfusion-weighted imaging (PWI). The levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) were measured by commercially available enzyme-linked immunosorbent assay kits. Protein levels were evaluated by western blot analysis. mRNA levels were evaluated by real time-polymerase chain reaction. Western blotting was used to estimate p65 translocation.

RESULTS

The behavioral analysis showed that PF could decrease the escape latency time (P<0.05), and increase the residence time of the original platform quadrant and the across platform frequency in water maze in VD rats (P<0.05). Likewise, PF remarkably promoted the rCBV (P<0.05), rCBF and decreased per minute MTT (P<0.05) in hippocampus of VD rats. Furthermore, PF decreased the release of IL-1β, IL-6 and TNF-α as well as inhibited the mRNA expression of IL-1β, IL-6 and TNF-α in the hippocampus of VD rats (P<0.05 or P<0.01). PF also could decrease the protein expressions of inducible nitric oxide synthase and cyclooxygenase-2 in the hippocampus of VD rats (P<0.05 or P<0.01). In addition, PF signifificantly inhibited the nuclear factor κB (NF-κB) pathway in the hippocampus of VD rats.

CONCLUSIONS

PF signifificantly attenuates cognitive impairment, improves hippocampus perfusion and inhibits inflflammatory response in VD rats. In addition, the anti-inflflammatory effects of PF might be due to inhibiting the NF-κB pathway. PF may be a potential clinical application in improving VD.

Diabetes Mellitus, Cognitive Impairment, and Traditional Chinese Medicine

Diabetes mellitus (DM) is a metabolic disorder affecting a large number of people worldwide. Numerous studies have demonstrated that DM can cause damage to multiple systems, leading to complications such as heart disease, cancer, and cerebrovascular disorders. Numerous epidemiological studies have shown that DM is closely associated with dementia and cognition dysfunction, with recent research focusing on the role of DM-mediated cerebrovascular damage in dementia. Despite the therapeutic benefits of antidiabetic agents for the treatment of DM-mediated cognitive dysfunction, most of these pharmaceutical agents are associated with various undesirable side-effects and their long-term benefits are therefore in doubt. Early evidence exists to support the use of traditional Chinese medicine (TCM) interventions, which tend to have minimal toxicity and side-effects. More importantly, these TCM interventions appear to offer significant effects in reducing DM-related complications beyond blood glucose control. However, more research is needed to further validate these claims and to explore their relevant mechanisms of action. The aims of this paper are (1) to provide an updated overview on the association between DM and cognitive dysfunction and (2) to review the scientific evidence underpinning the use of TCM interventions for the treatment and prevention of DM-induced cognitive dysfunction and dementia.