An enhanced cAMP pathway is responsible for the colonic hyper-secretory response to 5-HT in acute stress rats

Persimmon leaf extract alleviates chronic social defeat stress-induced depressive-like behaviors by preventing dendritic spine loss via inhibition of serotonin reuptake in mice

Background

Fresh or dried Persimmon leaves (Diospyros kaki Thunb.) exhibit preventive effects on cardiovascular and cerebrovascular diseases. However, their antidepressant effects and underlying mechanisms are unclear. Thus, we investigated mechanisms responsible for Persimmon leaf extract (PLE) activity on chronic social defeat stress (CSDS)-induced depressive-like behaviors in mice.

Methods

CSDS was used as a mouse model of depression. We performed the sucrose preference test (SPT), forced swim test (FST), and tail suspension test (TST) to identify depressive-like behavior. Spine density and dendritic morphology were assessed using Golgi staining. Neurochemicals were quantified by microdialysis, doublecortin by immunofluorescence, and cAMP using an ELISA kit. Finally, the levels of cortical proteins of phosphorylated cAMP-response element binding protein (CREB), brain-derived neurotrophic factor (BDNF), postsynaptic density synapsin-1 and protein 95 (PSD95) were quantified by western blot. 16S rRNA gene sequencing was used to detect fecal microbiota.

Results

Treatment of CSDS-subjected mice with PLE (30.0–60.0 mg/kg, i.g.) enhanced sucrose preference, decreased immobility times in the TST and FST but did not affect locomotor activity. Furthermore, persistent social defeat stress decreased dendritic spine density and dendritic length in the brain, as well as decreased PSD95 and synapsin-1 expression. PLE, interestingly, inhibited dendritic spine loss and increased synaptic protein levels. PLE also increased brain levels of 5-HT, cAMP, phosphorylated (p)-CREB, BDNF, PSD95, and synapsin-1 in mice subjected to CSDS. Furthermore, PLE increased their doublecortin-positive cell count in the hippocampal dentate gyrus. CSDS mice represented a distinct fecal microbiota cluster which differed compared with normal C57BL/6J mice, and the phenotype was rescued by PLE.

Conclusions

PLE alleviated CSDS-induced depressive behaviors and spinal damage by suppressing serotonin reuptake and activating the cAMP/CREB/BDNF signaling pathway. Simultaneously, PLE influenced the composition of the fecal microbiota in CSDS-subjected mice.

Supplementary information

The online version contains supplementary material available at 10.1186/s13020-022-00609-4.

Effect of TongXie-YaoFang on Cl(-) and HCO3 (-) Transport in Diarrhea-Predominant Irritable Bowel Syndrome Rats

TongXie-YaoFang (TXYF) can effectively alleviate the symptoms of diarrhea-predominant irritable bowel syndrome (D-IBS) patients. However, the curative mechanism has not been fully clarified. The study was designed to investigate the effect of TXYF on the colonic ion transport induced by serotonin (5-HT) in D-IBS rats. A method of multiple stress (neonatal maternal separation (NMS) combined with restraint stress (RS)) was used to induce the D-IBS model. The model rats were randomly divided into two groups: NMS + RS group and TXYF-formula group, and the normal control (no handling) rats were classified as NH group. In the NMS + RS group, the change of short-circuit current (ΔI sc) induced by 5-HT was lower than that in the NH and TXYF-formula groups. After removing of the extracellular Cl(-) or HCO3 (-) or basolateral Na(+) or blocking the cystic fibrosis transmembrane conductance regulator (CFTR), Na(+)-K(+)-2Cl(-) cotransporter (NKCC), Na(+)-HCO3 (-) cotransporter, Cl(-)/HCO3 (-) exchanger, K(+) channel, or Na(+)/K(+)-ATPase, respectively, there was no difference in 5-HT-induced ΔI sc among the three groups. These data suggest that TXYF can regulate 5-HT-induced Cl(-) and HCO3 (-) secretion, possibly mediated by the combined action of CFTR, NKCC, Na(+)-HCO3 (-) cotransporter, Cl(-)/HCO3 (-) exchanger, K(+) channel, and Na(+)/K(+)-ATPase.