[The physiological and psychological mechanisms of infra-slow oscillation].

Infra-slow oscillation (ISO) is a kind of brain rhythm between 0.01 and 0.5 Hz. ISO is widely distributed in multiple brain regions. As an important psychophysiological activity, the ISO interacts with high-frequency neural rhythm via cross-frequency coupling, but has different activity patterns from high-frequency neural activity. Physiologically, the ISO may be generated by the dynamic activity of thalamus, glia, and ions. Psychologically, the frequency, amplitude, and phase of ISO could all regulate cognitive activities, but in different ways. Investigations on the ISO expands the neural rhythm research to lower frequency range, further promoting the construction of rhythmic theory of brain function.

Ganoderma lucidum polysaccharide reduces melanogenesis by inhibiting the paracrine effects of keratinocytes and fibroblasts via IL-6/STAT3/FGF2 pathway.

Our previous study found that Ganoderma lucidum polysaccharide (GLP), bioactive ingredients from Ganoderma lucidum, protected fibroblasts from photoaging. However, whether GLP can affect melanogenesis in melanocytes through regulating paracrine mediators that secreted by keratinocytes and fibroblasts is unclear. We aimed to investigate the efficacy and mechanisms of action of GLP in melanogenesis by regulating paracrine effects of keratinocytes and fibroblasts. The effect of GLP on cell viability affected by GLP was measured by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. After an immortal keratinocyte line (HaCaT) and primary fibroblasts (FB) were treated with GLP, the supernatants of HaCaT and FB cells were collected and cocultured with an immortalized melanocyte line (PIG1). The expression levels of melanogenesis-associated genes in PIG1 cells were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis. Furthermore, FRS-2, ERK, JNK, and p38 phosphorylation levels were measured. Then, major melanogenic paracrine mediators in HaCaT and FB cells treated with GLP were evaluated by qRT-PCR and enzyme-linked immunosorbent assay (ELISA). In addition, the expression of IL-6 and STAT3 was examined in HaCaT and FB cells. GLP was not cytotoxic to HaCaT and FB cells. The supernatants of GLP-treated HaCaT and FB cells downregulated the expression levels of MITF, TYR, TYRP1, TYRP2, RAB27A, and FSCN1 genes and inhibited the phosphorylation of FRS-2, ERK, JNK, and p38 in PIG1 cells. GLP also decreased FGF2 secretion in HaCaT and FB cells. Moreover, GLP reduced IL-6 expression and STAT3 phosphorylation in HaCaT and FB cells. GLP reduced melanogenesis in melanocytes by inhibiting the paracrine effects of keratinocytes and fibroblasts via IL-6/STAT3/FGF2 pathway.