Tanshinone IIA Regulates Synaptic Plasticity in Mg2+-Free-Induced Epileptic Hippocampal Neurons via the PI3K/Akt Signaling Pathway

BACKGROUND

Tanshinone IIA (TSIIA) is an element of the effective ingredients of Salvia miltiorrhiza Bunge (Labiatae), exhibits a significant therapeutic effect in brain neuroprotection. The focus of this study was the examination of synaptic plasticity of in Mg2+-free-induced epileptic hippocampus neurons and how TSIIA protects against it.

METHODS

The purity of the primary hippocampal neurons extracted from Sprague Dawley rats was assessed within 24 hours by microtubule-associated protein (MAP2) immunofluorescence staining. A hippocampal neuron model for Mg2+-free-induced spontaneous recurrent epileptiform discharge was developed, five experimental groups were then randomized: blank (Blank), model (Model), TSIIA (TSIIA, 20 µM), LY294002 (LY294002, 25 µM), and TSIIA+LY294002 (TSIIA+LY294002, 20 µM+25 µM). FIJI software was used to examine variations of neurite complexity, total length of hippocampal neurons, number of primary dendrites and density of dendritic spines. Developmental regulation brain protein (Drebrin) and brain-derived neurotrophic factor (BDNF) expression was evaluated using immunofluorescence staining and the relative expression of phospho-protein kinase B (p-Akt)/Akt, BDNF, synaptophysin (SYN) and postsynaptic density 95 (PSD-95) determined by Western blot.

RESULTS

In contrast to the model group, TSIIA drastically reduced damage to synaptic plasticity of hippocampal neurons caused by epilepsy (p < 0.05). The TSIIA group showed a significant increase in the relative expression of PSD-95, SYN, BDNF, and p-Akt/Akt (p < 0.01).

CONCLUSIONS

TSIIA was effective in reducing harm to the synaptic plasticity of hippocampal neurons induced by persistent status epilepticus, with the possible mechanism being regulation of the phosphatidylinositol 3-kinase 56 (PI3K)/Akt signaling pathway.

Beneficial effects of red and blue light on potato leaf antioxidant capacity and tuber bulking

Artificial light application is an effective method for promoting potato production in indoor facilities. In this study, we assessed the effects of different combinations of red (R) and blue (B) light application on potato leaf and tuber growth. Potato plantlets were transplanted under W (white light, control), RB5-5 (50% R + 50% B), RB3-7 (30% R + 70% B to 70% R + 30% B) and RB1-9 (10% R + 90% B to 90% R + 10% B), and ascorbic acid (AsA) metabolism in leaves and cytokinin (CTK), auxin (indole-3-acetic acid, IAA), abscisic acid (ABA), and gibberellin (GA) levels in tubers were measured. At 50 days of treatment, potato leaves had significantly higher L-galactono-1,4-lactone dehydrogenase (GalLDH) activity and utilized AsA faster under RB1-9 treatment than under RB3-7 treatment. CTK/IAA and ABA/GA ratios in large tubers under W treatment did not differ significantly from those under RB1-9 treatment, which had higher levels than those under RB5-5 and RB3-7 treatment at 50 days. However, under RB1-9 treatment, total leaf area decreased rapidly from 60 to 75 days compared with plants under RB3-7 treatment. Tuber dry weight per plant under W and RB5-5 treatment approached a plateau at 75 days. At 80 days, RB3-7 treatment significantly improved ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase activity compared with RB1-9 treatment. RB1-9 treatment with a high ratio of blue light increased CTK/IAA and ABA/GA to improve tuber bulking at 50 days, while RB3-7 treatment with a high ratio of red light stimulated AsA metabolic pathway to delay leaf oxidation and maintain tuber biomass accumulation at 80 days. For the indoor potato cultivation, RB3-7 treatment had a higher proportion of medium-sized tubers, thus being a suitable light treatment.