ABSTRACT
Neurogenesis decline in hippocampal dentate gyrus (DG) participates in stress-induced depressive-like behaviors, but the underlying mechanism remains poorly understood. Here, we observed low-expression of NOD-like receptor family pyrin domain containing 6 (NLRP6) in hippocampus of stress-stimulated mice, being consistent with high corticosterone level. NLRP6 was found to be abundantly expressed in neural stem cells (NSCs) of DG. Both Nlrp6 knockout (Nlrp6-/-) and NSC-conditional Nlrp6 knockout (Nlrp6CKO) mice were susceptible to stress, being more likely to develop depressive-like behaviors. Interestingly, NLRP6 was required for NSC proliferation in sustaining hippocampal neurogenesis and reinforcing stress resilience during growing up. Nlrp6 deficiency promoted esophageal cancer-related gene 4 (ECRG4) expression and caused mitochondrial dysfunction. Corticosterone as a stress factor significantly down-regulated NLRP6 expression, damaged mitochondrial function and suppressed cell proliferation in NSCs, which were blocked by Nlrp6 overexpression. ECRG4 knockdown reversed corticosterone-induced NSC mitochondrial function and cell proliferation disorders. Pioglitazone, a well-known clinical drug, up-regulated NLRP6 expression to inhibit ECRG4 expression in its protection against corticosterone-induced NSC mitochondrial dysfunction and proliferation restriction. In conclusion, this study demonstrates that NLRP6 is essential to maintain mitochondrial homeostasis and proliferation in NSCs, and identifies NLRP6 as a promising therapeutic target for hippocampal neurogenesis decline linked to depression.
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OBJECTIVE： To investigate the effects of crystal form on in vivo and in vitro behavior of Astilbin nanosuspensions （AT-NS）. METHODS： AT-NS1 and AT-NS2 were prepared by precipitation method and miniaturized media milling method respectively. The particle size and polydispersity index （PDI） were determined by laser particle size analyzer. X-ray diffraction （XRD）， scanning electron microscopy （SEM）， HPLC and paddle method were used to analyze and compare the structure characteristics， appearance morphology and in vitro dissolution of AT raw material， AT-NS1 and AT-NS2. Totally 15 healthy male SD rats were randomly divided into AT raw material， AT-NS1 and AT-NS2 group， with 5 rats in each group. They were given relevant medicine suspension 120 mg/kg （using water as solvent） intragastrically； blood samples were collected from orbit before medication （0 min） and 5， 10， 20， 30， 60， 120， 240， 480 min after medication. Using rutin as internal standard， HPLC method was used to determine plasma concentration of AT in rats. Pharmacokinetic parameters were calculated by using DAS 2.0 software and then compared. RESULTS： The particle sizes of AT-NS1 and AT-NS2 were （212.48±0.32） nm and （226.36±2.29） nm， respectively； PDI were 0.129 3±0.026 3 and 0.254 7±0.012 4. XRD analysis showed AT-NS1 was amorphous， and AT-NS2 was crystalline. Diffraction peaks of both were different from those of AT raw material. SEM analysis showed that AT-NS1 and AT-NS2 were similar in morphology， and they were spherical and uniform in size； AT raw material was lump with large particle size and different sizes. Results of dissolution tests showed that accumulative dissolution of AT raw material， AT-NS1 and AT-NS2 were 4.54％， 35.01％， 12.22％ at 1 h； accumulative dissolution of them were 24.01％， 81.14％， 64.69％ at 12 h； accumulative dissolution of them were 36.04％， 84.47％， 85.86％ at 24 h， respectively. Results of pharmacokinetic study showed， compared with AT raw material group， cmax and AUC0-∞ of AT-NS1 and AT-NS2 groups as well as t1/2z of AT-NS1 group were increased significantly， while tmax of AT-NS1 group was significantly reduced significantly （P＜0.05）. Compared with AT-NS2 goup， cmax， AUC0-∞ and t1/2z of AT-NS1 group were increased significantly， while tmax was reduced significantly （P＜0.05）. CONCLUSIONS： When AT is prepared into NS， dissolution in vitro and oral absorption in vivo of AT are increased significantly. In a short time， the dissolution/absorption of amorphous NS is faster than crystalline NS.
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Objective To analyse the antinociceptive effect of muscle spindle afferents and the involved mechanism.Methods The single unit of wide dynamic range(WDR) neurons in the spinal cord dorsal horn were recorded extracelluarly.The effects of muscle spindle afferents elicited by intravenous administration of succinylcholine (Sch) on nociceptive responses (C-fibres-evoked responses,C-responses) of WDR neurons were observed before and after bilateral lesions of ventrolateral periaqueduct gray (PAG).And the effects of muscle spindle afferents on the spontaneous discharge of the tail-flick related cell in the rostral ventro medial medulla (RVM) and on the spontaneous discharge of the PAG neurons were observed.Results The C-responses of WDR neurons were significantly inhibited by muscle spindle afferents,and the inhibitory effects were reduced by bilateral lesions of ventrolateral PAG.The spontaneous discharge of the off-cell in the RVM was excited while the on-cell was inhibited by intravenous administration of Sch.The spontaneous discharge of the PAG neurons were excited by muscle spindle afferents.Conclusion Muscle spindle afferents show a distinct effect of antinociception.PAG-RVM descending inhibitory system may play an important role in this nociceptive modulative mechanism.
ABSTRACT
Objective: To better understand the effect of propofol on the spinal cord levels, and investigate whether there are different effects of propofol between nociceptive input and non-nociceptive input. Method: All Sprague-Dawley rats were spinally transected, the effect of propofol (2mg/kg, Ⅳ) on C response to the firing of electromyography, and the discharges of dorsal horn neurons were observed. Result: Propofol can produce a profound inhibition on C response,early discharges,late discharges and spontaneous discharges. Compared with early discharges, the extent of inhibition of late discharges increased but the lasting time was shorten. Conclusion: Propofol can suppress the transmission of nociceptive and non-nociceptive stimulus in spinal cord with stronger inhibition on nociceptive input,and the shorter lasting time. It is indicated that the loss of sense and pain results from the effect of propofol on the spinal cord.