Background:The development of ketamine-like rapid antidepressants holds promise for enhancing the therapeutic efficacy of depression,but the underlying cellular and molecular mechanisms remain unclear.Implicated in de...Background:The development of ketamine-like rapid antidepressants holds promise for enhancing the therapeutic efficacy of depression,but the underlying cellular and molecular mechanisms remain unclear.Implicated in depression regulation,the neuropeptide pituitary adenylate cyclase-activating polypeptide(PACAP)is investigated here to examine its role in mediating the rapid antidepressant response.Methods:The onset of antidepressant response was assessed through depression-related behavioral paradigms.The signaling mechanism of PACAP in the hippocampal dentate gyrus(DG)was evaluated by utilizing site-directed gene knockdown,pharmacological interventions,or optogenetic manipulations.Overall,446 mice were used for behavioral and molecular signaling testing.Mice were divided into control or experimental groups randomly in each experiment,and the experimental manipulations included:chronic paroxetine treatments(4 d,9 d,14 d)or a single treatment of ketamine;social defeat or lipopolysaccharides-injection induced depression models;different doses of PACAP(0.4 ng/site,2 ng/site,4 ng/site;microinjected into the hippocampal DG);pharmacological intra-DG interventions(CALM and PACAP6-38);intra-DG viral-mediated PACAP RNAi;and opotogenetics using channelrhodopsins 2(ChR2)or endoplasmic natronomonas halorhodopsine 3.0(eNpHR3.0).Behavioral paradigms included novelty suppressed feeding test,tail suspension test,forced swimming test,and sucrose preference test.Western blotting,ELISA,or quantitative real-time PCR(RT-PCR)analysis were used to detect the expressions of proteins/peptides or genes in the hippocampus.Results:Chronic administration of the slow-onset antidepressant paroxetine resulted in an increase in hippocampal PACAP expression,and intra-DG blockade of PACAP attenuated the onset of the antidepressant response.The levels of hippocampal PACAP expression were reduced in both two distinct depression animal models and intra-DG knockdown of PACAP induced depression-like behaviors.Conversely,a single infusion of PACAP into the DG region produced a rapid and sustained antidepressant response in both normal and chronically stressed mice.Optogenetic intra-DG excitation of PACAP-expressing neurons instantly elicited antidepressant responses,while optogenetic inhibition induced depression-like behaviors.The longer optogenetic excitation/inhibition elicited the more sustained antidepressant/depression-like responses.Intra-DG PACAP infusion immediately facilitated the signaling for rapid antidepressant response by inhibiting calcium/calmodulin-dependent protein kinaseⅡ(CaM KⅡ)-eukaryotic elongation factor 2(eEF2)and activating the mammalian target of rapamycin(mTOR).Pre-activation of CaMKⅡsignaling within the DG blunted PACAP-induced rapid antidepressant response as well as eEF2-mTOR-brain-derived neurotrophic factor(BDNF)signaling.Finally,acute ketamine treatment upregulated hippocampal PACAP expression,whereas intraDG blockade of PACAP signaling attenuated ketamine’s rapid antidepressant response.Conclusions:Activation of hippocampal PACAP signaling induces a rapid antidepressant response through the regulation of CaMKⅡinhibition-governed eEF2-mTOR-BDNF signaling.展开更多
AIM:To determine the effect of pituitary adenylate cy-clase-activating polypeptide (PACAP) on left gastric artery (LGA) flow and to unveil the structural or functional important sites that may be critical for discrimi...AIM:To determine the effect of pituitary adenylate cy-clase-activating polypeptide (PACAP) on left gastric artery (LGA) flow and to unveil the structural or functional important sites that may be critical for discrimination of different receptor subtypes. METHODS: Peptides, including PACAP-27, PACAP-38, amino acid substituted PACAP-27 and C-terminus truncated analogues PACAP (27-38), were synthesized by a simultaneous multiple solid-phase peptide synthesizer. Flow probes of an ultrasound transit-time blood flowmeter were placed around the LGA of beagle dogs. Whenpeptides were infused intravenously, the blood flow was measured.RESULTS: [Ala4, Val5]-PACAP-27 caused a concentration-dependent vasodepressor action which was similar to that caused by PACAP-27. The LGA blood flow response to [Ala4, Val5]-PACAP-27 was significantly higher than that to PACAP-27, which was similar to that to vasoactive intestinal polypeptide (VIP) at the same dose. [Ala6]-PACAP-27 did not increase the peak LGA ? ow. [Gly8]-PACAP-27 showed a similar activity to VIP. [Asn24, Ser25, Ile26]-PACAP-27 did not change the activity of peptides at all doses. CONCLUSION: NH2 terminus is more important to biological activity of peptides and specifi c receptor recognition than COOH-terminus.展开更多
Pituitary adenylate cyclase-activating polypeptide（PACAP） is an endogenous peptide with neuroprotective effects on retinal neurons, but the precise mechanism underlying these effects remains unknown. Considering the...Pituitary adenylate cyclase-activating polypeptide（PACAP） is an endogenous peptide with neuroprotective effects on retinal neurons, but the precise mechanism underlying these effects remains unknown. Considering the abundance of mitochondria in retinal ganglion cells（RGCs）, we postulate that the protective effect of PACAP is associated with the regulation of mitochondrial function. RGC-5 cells were subjected to serum deprivation for 48 hours to induce apoptosis in the presence or absence of 100 nM PACAP. As revealed with the Cell Counting Kit-8 assay, PACAP at different concentrations significantly increased the viability of RGC-5 cells. PACAP also inhibited the excessive generation of reactive oxygen species in RGC-5 cells subjected to serum deprivation. We also showed by flow cytometry that PACAP inhibited serum deprivation-induced apoptosis in RGC-5 cells. The proportions of apoptotic cells and cells with mitochondria depolarization were significantly decreased with PACAP treatment. Western blot assays demonstrated that PACAP increased the levels of Bcl-2 and inhibited the compensatory increase of PAC1. Together, these data indicate protective effects of PACAP against serum deprivation-induced apoptosis in RGCs, and that the mechanism of this action is associated with maintaining mitochondrial function.展开更多
基金supported by the National Key Research and Development Program of China(2022YFE0201000)the National Natural Science Foundation of China(82174002,82104416,82204652)the High-Level University Development Program of Guangdong Province,and the Guangzhou Key Science and Technology Research and Development Project(202206010109)。
文摘Background:The development of ketamine-like rapid antidepressants holds promise for enhancing the therapeutic efficacy of depression,but the underlying cellular and molecular mechanisms remain unclear.Implicated in depression regulation,the neuropeptide pituitary adenylate cyclase-activating polypeptide(PACAP)is investigated here to examine its role in mediating the rapid antidepressant response.Methods:The onset of antidepressant response was assessed through depression-related behavioral paradigms.The signaling mechanism of PACAP in the hippocampal dentate gyrus(DG)was evaluated by utilizing site-directed gene knockdown,pharmacological interventions,or optogenetic manipulations.Overall,446 mice were used for behavioral and molecular signaling testing.Mice were divided into control or experimental groups randomly in each experiment,and the experimental manipulations included:chronic paroxetine treatments(4 d,9 d,14 d)or a single treatment of ketamine;social defeat or lipopolysaccharides-injection induced depression models;different doses of PACAP(0.4 ng/site,2 ng/site,4 ng/site;microinjected into the hippocampal DG);pharmacological intra-DG interventions(CALM and PACAP6-38);intra-DG viral-mediated PACAP RNAi;and opotogenetics using channelrhodopsins 2(ChR2)or endoplasmic natronomonas halorhodopsine 3.0(eNpHR3.0).Behavioral paradigms included novelty suppressed feeding test,tail suspension test,forced swimming test,and sucrose preference test.Western blotting,ELISA,or quantitative real-time PCR(RT-PCR)analysis were used to detect the expressions of proteins/peptides or genes in the hippocampus.Results:Chronic administration of the slow-onset antidepressant paroxetine resulted in an increase in hippocampal PACAP expression,and intra-DG blockade of PACAP attenuated the onset of the antidepressant response.The levels of hippocampal PACAP expression were reduced in both two distinct depression animal models and intra-DG knockdown of PACAP induced depression-like behaviors.Conversely,a single infusion of PACAP into the DG region produced a rapid and sustained antidepressant response in both normal and chronically stressed mice.Optogenetic intra-DG excitation of PACAP-expressing neurons instantly elicited antidepressant responses,while optogenetic inhibition induced depression-like behaviors.The longer optogenetic excitation/inhibition elicited the more sustained antidepressant/depression-like responses.Intra-DG PACAP infusion immediately facilitated the signaling for rapid antidepressant response by inhibiting calcium/calmodulin-dependent protein kinaseⅡ(CaM KⅡ)-eukaryotic elongation factor 2(eEF2)and activating the mammalian target of rapamycin(mTOR).Pre-activation of CaMKⅡsignaling within the DG blunted PACAP-induced rapid antidepressant response as well as eEF2-mTOR-brain-derived neurotrophic factor(BDNF)signaling.Finally,acute ketamine treatment upregulated hippocampal PACAP expression,whereas intraDG blockade of PACAP signaling attenuated ketamine’s rapid antidepressant response.Conclusions:Activation of hippocampal PACAP signaling induces a rapid antidepressant response through the regulation of CaMKⅡinhibition-governed eEF2-mTOR-BDNF signaling.
基金Supported by (in part) Grants from Ministry of Education,Culture,Science,and Technology,Japan Society for the Promotion of Science and Special Fund of Six-Talented Peak of Jiangsu Province,No.07-B-15 (IB07)
文摘AIM:To determine the effect of pituitary adenylate cy-clase-activating polypeptide (PACAP) on left gastric artery (LGA) flow and to unveil the structural or functional important sites that may be critical for discrimination of different receptor subtypes. METHODS: Peptides, including PACAP-27, PACAP-38, amino acid substituted PACAP-27 and C-terminus truncated analogues PACAP (27-38), were synthesized by a simultaneous multiple solid-phase peptide synthesizer. Flow probes of an ultrasound transit-time blood flowmeter were placed around the LGA of beagle dogs. Whenpeptides were infused intravenously, the blood flow was measured.RESULTS: [Ala4, Val5]-PACAP-27 caused a concentration-dependent vasodepressor action which was similar to that caused by PACAP-27. The LGA blood flow response to [Ala4, Val5]-PACAP-27 was significantly higher than that to PACAP-27, which was similar to that to vasoactive intestinal polypeptide (VIP) at the same dose. [Ala6]-PACAP-27 did not increase the peak LGA ? ow. [Gly8]-PACAP-27 showed a similar activity to VIP. [Asn24, Ser25, Ile26]-PACAP-27 did not change the activity of peptides at all doses. CONCLUSION: NH2 terminus is more important to biological activity of peptides and specifi c receptor recognition than COOH-terminus.
基金supported by grants from the Medical Scientific Research Foundation of Guangdong Province of China,No.A2016271the Natural Science Foundation of Guangdong Province of China,No.2016A030313208the Science and Technology Planning Project of Guangdong Province of China,No.2014A020212393
文摘Pituitary adenylate cyclase-activating polypeptide（PACAP） is an endogenous peptide with neuroprotective effects on retinal neurons, but the precise mechanism underlying these effects remains unknown. Considering the abundance of mitochondria in retinal ganglion cells（RGCs）, we postulate that the protective effect of PACAP is associated with the regulation of mitochondrial function. RGC-5 cells were subjected to serum deprivation for 48 hours to induce apoptosis in the presence or absence of 100 nM PACAP. As revealed with the Cell Counting Kit-8 assay, PACAP at different concentrations significantly increased the viability of RGC-5 cells. PACAP also inhibited the excessive generation of reactive oxygen species in RGC-5 cells subjected to serum deprivation. We also showed by flow cytometry that PACAP inhibited serum deprivation-induced apoptosis in RGC-5 cells. The proportions of apoptotic cells and cells with mitochondria depolarization were significantly decreased with PACAP treatment. Western blot assays demonstrated that PACAP increased the levels of Bcl-2 and inhibited the compensatory increase of PAC1. Together, these data indicate protective effects of PACAP against serum deprivation-induced apoptosis in RGCs, and that the mechanism of this action is associated with maintaining mitochondrial function.
