Effect of sulfated polysaccharides from Laminaria japonica on vascular endothelial cells in psychological stress rats

Ethnopharmacological relevance

Laminaria japonica is a popular seafood and medicinal plant in China. Laminaria japonica is used in traditional Chinese medicine to treat and prevent hypertension and edema.

Materials and methods

The vascular protective activity and mechanism of sulfated polysaccharides were studied in adrenalin-induced vascular endothelial damage in rats after psychological stress (PS). Vehicle (sham and PS groups), sulfated polysaccharide from Laminaria japonica (LP; 1 mg/kg and 5 mg/kg) and enoxaparin sodium (1 IU/kg, reference drug) were all administered for 10 days. Behavioral changes were recorded. Plasma levels of adrenalin, cortisol, monoamine oxidase (MAO), semicarbazide-sensitive amine oxidase (SSAO), formaldehyde, H₂O₂, nitric oxide (NO), endothelin-1 (ET-1), 6-keto-prostaglandin F_1a (6-keto-PGF_1a), and thromboxane B₂ (TXB₂) were measured. Endothelium-dependent relaxation of the thoracic aorta was measured and transmission electron microscopy of aortic vessels was performed.

Results

Adrenalin metabolites in plasma were significantly lower (P<0.01) in rats after LP administration compared with those in the PS groups. The normalized ratios of plasma NO/ET-1 and 6-keto-PGF_1a/TXB₂ were maintained and endothelium-dependent relaxation of the aorta was greatly enhanced after LP treatment (P<0.05). Morphological alterations were observed in vascular endothelial cells (VECs) in PS rats, with a higher number of lysosomes and vague mitochondrial cristae compared with those in the sham group. However, these histopathological changes were markedly alleviated after LP treatment.

Conclusions

This study shows a protective effect of LP on VECs in PS rats. LP can regulate plasma levels of NO, ET-1, and 6-keto-PGF_1a, enhance endothelium-dependent relaxation, and alleviate histopathological changes of lysosomes and mitochondria in VECs. The potential mechanism of LP on VECs in PS rats is related to its function of reducing metabolites of adrenalin.