Visceral hypersensitivity as a common clinical manifestation of irritable bowel syndrome (IBS) may contribute to the development of chronic visceral pain. Our prior studies authenticated that the activation of the corticotropin-releasing factor (CRF) neurons in paraventricular nucleus (PVN) contributed to visceral hypersensitivity in mice, but puzzles still remain with respect to the underlying hyperactivation of corticotropin-releasing factor neurons. Herein, we employed maternal separation (MS) to establish mouse model of visceral hypersensitivity. The neuronal circuits associated with nociceptive hypersensitivity involved paraventricular nucleus CRF neurons by means of techniques such as behavioral test, pharmacology, molecular biology, retrograde neuronal circuit tracers, electrophysiology, chemogenetics and optogenetics. MS could predispose the elevated firing frequency of CRF neurons in PVN in murine adulthood, which could be annulled via the injection of exogenous GABA (0.3mM, 0.2µl) into PVN. The PVN-projecting GABAergic neurons were mainly distributed in the anterior ventral (AV) region in the bed nucleus of stria terminalis (BNST), wherein the excitability of these GABAergic neurons was reduced. Casp3 virus was utilized to induce apoptosis of GABA neurons in BNST-AV region, resulting in the activation of CRF neurons in PVN and visceral hyperalgesia. In parallel, chemogenetic and optogenetic approaches to activate GABAergic BNSTAV-PVN circuit in MS mice abated the spontaneous firing frequency of PVN CRF neurons and prevented the development of visceral hypersensitivity. A priori, PVNCRF-projecting GABAergic neurons in BNST-AV region participated in the occurrence of visceral hypersensitivity induced by MS. Our research may provide a new insight into the neural circuit mechanism of chronic visceral pain.

Visceral hypersensitivity is a highly complex and subjective phenomenon associated with multiple levels of the nervous system and a wide range of neurotransmission. The dorsal horn (DH) in spinal cord relays the peripheral sensory information into the brain. Small conductance Ca2+-activated K+ (SK) channels regulate neuronal excitability and firing by allowing K+ to efflux in response to increase in the intracellular Ca2+ level. In this study, we examined the influence of SK2 channels in the spinal DH on the pathogenesis of visceral hypersensitivity induced by colorectal distension (CRD) in rats. Electrophysiological results showed that rats with visceral hypersensitivity presented a decrease in the SK channel-mediated afterhyperpolarization current (IAHP), and an increase in neuronal firing rates and c-Fos positive staining in the spinal DH. Western blot data revealed a decrease in the SK2 channel protein in the membrane fraction. Moreover, intrathecal administration of the SK2 channel activator 1-EBIO or CyPPA alleviated visceral hypersensitivity, reversed the decrease in IAHP and the increase in neuronal firing rates in spinal DH in rats that experienced CRD. 1-EBIO or CyPPA effect could be prevented by SK2 channel blocker apamin. CRD induced an increase in c-Fos protein expression in the spinal DH, which was prevented by 1-EBIO. Together, these data suggest that visceral hypersensitivity and pain is associated with a decrease in the number and function of membrane SK2 channels in the spinal DH. Pharmacological manipulation of SK2 channels may open a new avenue for the treatment of visceral hypersensitivity and pain.Highlights: Neonatal colorectal distension induced visceral hypersensitivity in rats.Visceral hypersensitivity rats presented a decrease in afterhyperpolarization current (IAHP) and membrane SK2 channel protein in the spinal dorsal horn.Visceral hypersensitivity rats presented an increase in neuronal firing rate in the spinal dorsal horn.Intrathecal administration of SK2 channel activator 1-EBIO or CyPPA prevented visceral hypersensitivity and decrease in IAHP.

BackgroundDespite its rarity, studies have shown the incidence of gastric neuroendocrine tumors (G‐NETs) is increasing. This study investigated the risk factors affecting the survival of G‐NETs patients and their prognosis over time.MethodA retrospective analysis of 506 G‐NETs patients who underwent surgery for nonmetastatic disease from the Surveillance, Epidemiology and End Result database from 1988 to 2011 was conducted. Multivariate Cox regression analyses identified the prognostic factors affecting overall survival (OS) and disease‐specific survival (DSS). Three‐year conditional survival (COS3 and CDS3) estimates at “x” year after treatment were calculated as follows: COS3 = OS(x + 3)/OS(x) and CDS3 = DSS(x + 3)/DSS(x).ResultsThe 1‐, 3‐, and 5‐year OS rates of all patients after surgery were 90.2%, 77.3%, and 68.8%, respectively. The 1‐, 3‐, and 5‐year DSS rates after surgery were 93.9%, 84.5%, and 80.9%, respectively. In the multivariate analysis, age, tumor grade, and T stage were independent prognostic factors of OS and DSS (all P < 0.05). With 1‐, 3‐, and 5‐year survivorship, the COS3 improved by +5.2 (82.2%), +7.2 (84.4%), and +8.5 (85.5%), respectively, and the CDS3 improved by +4.4 (89.4%), +9.1 (94.1%), and +12.5 (97.5%), respectively. Notably, the CDS3 improved dramatically among patients with advanced stage disease (eg, N0 stage: 93.0%‐98.9%, Δ5.9% vs N1 stage: 52.0%‐95.7%, Δ43.7%).ConclusionFor G‐NETs patients, age, tumor grade, T stage, and N stage were the clinicopathological factors significantly associated with prognosis. There were excellent outcomes for most G‐NETs patients, with a CDS3 of greater than 90% across all independent prognostic factors after 5 years of survival.

A number of acute or repeated stimuli can induce expression of DeltaFosB (ΔFosB), a transcription factor derived from the fosB gene (an osteosarcoma viral oncogene) via alternative splicing. ΔFosB protein is currently viewed as a ‘molecular switch’ to repeated stimuli that gradually converts acute responses into relatively stable adaptations underlying long-term neural and behavioral plasticity. ΔFosB has received extensive attention in drug addition, depression, and stress adaptation, but changes in ΔFosB protein expression during pain is not fully understood. In this study we explored ΔFosB expression in the medial prefrontal cortex (mPFC) of rats experiencing chronic or acute stress-induced pain. Our data reveal that chronic pain induced by neonatal colorectal distension, chronic constriction injury (CCI) of the sciatic nerve, or maternal separation was associated with an increase in ΔfosB protein expression in mPFC, but acute application of acetic acid or zymosan did not alter the ΔFosB protein expression. ΔFosB expression in the rat visual cortex, a non pain-related brain region, did not change in response to (CCI) of the sciatic nerve and acetic acid treatment. In conclusion, our results indicate that ΔFosB protein expression is significantly elevated in rats that have experienced chronic pain and stress, but not acute pain. The ΔFosB protein may serve as an important transcription factor for chronic stress-induced pain. Further research is needed to improve the understanding of both the upstream signaling leading to ΔFosB protein expression as well as the regulation of ΔFosB gene expression in cortical neurons.

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