Inhibitory Effect of 5-Adenylic Acid on Bitter Taste of Antipsychotic Drugs

The purpose of the present study was to examine the effect of adenylic acid (adenosine 5-monophosphate;AMP), a known nutritional enhancer, on inhibiting the bitterness of antipsychotic medicines administered to patients with mental illnesses, including children. First, we chose four antipsychotic medicines, amitriptyline hydrochloride (AMT), chlorpromazine hydrochloride (CPZ), haloperidol (HPD) and risperidone (RIS) and evaluated the inhibition of their bitterness by AMP through taste sensor measurements. AMP showed a significant bitterness inhibition effect on all drugs. Second, MarvinSketch analysis revealed the potential formation of electrostatic interactions between ionic forms (IV) of AMP and ionic (cationic) forms of each drug, which resulted in bitterness suppression. Third, chemical shift perturbations in 1H-NMR studies suggested an interaction between the phosphate group of AMP and amino group of AMT, CPZ, HPD and RIS. Last, conventional elution experiments of up to 1 min simulating oral cavity conditions were performed for 1 whole AMT tablet, half AMT tablet, crushed half AMT tablet, and crushed AMT tablet containing AMP powder/solution (1, 3 mM potency). The taste sensor output values of the crushed AMT tablet containing AMP powder/solution (1, 3 mM potency) were significantly lower than those of the crushed tablet.

Adenylate cyclase activates the cAMP signalling pathway to enhance platelet-rich plasma-treated Achilles tendon disease,a theoretical bioinformatics-based study

The effectiveness of platelet-rich plasma(PRP)for the treatment of Achilles tendon disorders still needs to be evaluated through a series of prospective studies,but genomic analysis can reveal the existence of complementary PRP treatment options.Based on the 96 platelet activation-related genes in the Kyoto Encyclopedia of Genes and Genomes(KEGG)database,we performed Gene Ontology functional enrichment analysis and KEGG enrichment analysis,pathway correlation analysis,and enrichment mapping to determine the enrichment results of the gene set enrichment analysis and found that the cAMP signalling pathway may be the key to enhancing the effectiveness of PRP treatment.The cAMP signalling pathway interacts with the Rap1 signalling pathway and cGMPPKG signalling pathway to mediate the entire pathophy-siological process of Achilles tendon disease.Moreover,ADCY1-9 may be the key to the activation of the cAMP signalling network.Further based on the data in the Gene Expression Omnibus database,it was found that ADCY4 and ADCY7 may be the players that play a major role,associated with the STAT4-ADCY4-LAMA5 axis and the GRbeta-ADCY7-SEMA3C axis,which is expected to be a complementary target for enhancing the efficacy of PRP in the treatment of Achilles tendon disease.

Phylogenetic relationships of 18 passerines based on Adenylate Kinase Intron 5 sequences

The 18 species of bird studied originally are known to belong to muscicapids, robins and sylviids of passerines, but some dis- putations are always present in their classification systems. In this experiment, phylogenetic relationships of 18 species of passerines were studied using Adenylate Kinase lntron 5 （AKS） sequences and DNA techniques. Through sequences analysis in comparison with each other, phylogenetic tree figures of 18 species of passerines were constructed using Neighbor-Joining （N J） and Maximum-Parsimony （MP） meth- ods . The results showed that sylviids should be listed as an independent family, while robins and flycatchers should be listed into Musci- capidae. Since the phylogenetic relationships between long-tailed tits and old world warblers are closer than that between long-tailed tits and parids, the long-tailed tits should be independent of paridae and be categorized into aegithalidae. Muscicapidae and Paridae are known to be two monophylitic families, but Sylviidae is not a monophyletic group. AK5 sequences had better efficacy in resolving close relationships of interspecies among intrageneric groups.

Effect of Fish Oil on (-Adrenoceptors and the Activity of Adenylate Cyclase on Myocardial Membrane in Rats

Effects of fish oil on β-adrenoceptors as well as the activity of adenylate cyclase (AC) on rat myocardial membrane were investigated.Supplementation with fish oil had no significant effect on basal activity of AC on myocardial membrane whereas it could markedly inhibit the AC activity stimulated by isoproterenol (ISO). Radioligand binding assays showed that supplementation with fish oil had no effect on Bmax and Kd, compared with saline control. However, supplementation with sheep oil could markedly reduce both the Kd and Bmax, compared with saline control. And the Kd of sheep oil group was greatly decreased than that of fish oil group. The results suggested that supplementation with fish oil mainly affected the activation of AC, not β-adrenoceptor itself.

Effects of Meglumine Cyclic Adenylate Pretreatment on Systemic inflammatory Response Syndrome Induced by Lipopolysaccharide in Rats

Studies showed that the use of cyclic adenosine monophosphate(cAMP) substitutes or intracellular c AMP activators increased intracellular cAMP level, causing anti-inflammatory effects. This study was to investigate the effects of pretreatment with meglumine cyclic adenylate(MCA), a compound of meglumine and cAMP, on systemic inflammation induced by lipopolysaccharide(LPS) in rats. Eighteen adult male Sprague-Dawley rats were randomly divided into 3 groups(n=6 each): control group(NS group), LPS group(LPS group) and LPS with MCA pretreatment group(MCA group). Systemic inflammation was induced with LPS 10 mg/kg injected via the femoral vein in LPS and MCA groups. In MCA group, MCA 2 mg/kg was injected via the femoral vein 20 min before LPS injection, and the equal volume of normal saline was given in NS and LPS groups at the same time. Three hours after LPS injection, the blood samples were taken from the abdominal aorta for determination of plasma concentrations of TNF-α, IL-1, IL-6, IL-10, cAMP by ELISA and NF-κBp65 expression by Western blotting. The experimental results showed that inflammatory and antiinflammatory indices were increased in LPS group compared to NS group; inflammatory indices were declined and anti-inflammatory indices were increased in MCA group relative to LPS group. Our study suggested that MCA pretreatment may attenuate LPS-induced systemic inflammation.

Inhibition of retinal ganglion cell apoptosis: regulation of mitochondrial function by PACAP

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.

Two-step Enzymatic Synthesis of Guanine Arabinoside

The chemical synthesis of Guanine arabinoside （ara-G） is extremely complex, time-consuming, and seriously polluted. A two-step enzymatic synthesis process was developed to acquire ara-G easily. 2,6-Diaminopurine arabinoside （ara-DA） was first synthesized with purine nucleoside phosphorylase and pyrimidine nucleoside phosphorylase produced by Enterobacter aerogenes DGW-07. The conversion yield of ara-DA could reach above 90% when the reaction liquid contained 30 mmol·L^-1 uracil arabinoside as arabinose donor, 10 mmol·L^- 1 2,6-diaminopurine as arabinose acceptor in pH 7.0 20 mmol·L^-1 phosphate buffer, and reacted at 60℃ for 48h. Then, ara-DA was effectively transformed into ara-G with adenylate deaminase produced by Aspergillus oryzae DAW-01. The total process had no complex separation and purification.

Effects of Yulangsan polysaccharide on monoamine neurotransmitters, adenylate cyclase activity and brain-derived neurotrophic factor expression in a mouse model of depression induced by unpredictable chronic mild stress

The present study established a mouse model of depression induced by unpredictable chronic mild stress. The model mice were treated with Yulangsan polysaccharide （YLSPS; 150, 300 and 600 mg/kg） for 21 days, and compared with fluoxetine-treated and normal control groups. Enzyme-linked immunosorbent assay, radioimmunity and immunohistochemical staining showed that following treatment with YLSPS （300 and 600 mg/kg）, monoamine neurotransmitter levels, prefrontal cortex adenylate cyclase activity and hippocampal brain-derived neurotrophic factor expression were significantly elevated, and depression-like behaviors were improved. Open-field and novelty-suppressed feeding tests showed that mouse activity levels were increased and feeding latency was shortened following treatment. Our results indicate that YLSPS inhibits depression by upregulating monoamine neurotransmitters, prefrontal cortex adenylate cyclase activity and hippocampal brain-derived neurotrophic factor expression.

Cloning,tissue distribution and effects of fasting on pituitary adenylate cyclase-activating polypeptide in largemouth bass

Pituitary adenylate cyclase activating polypeptide （PACAP） has a wide range of biological functions. We cloned the full-length cDNAs encoding PACAP and PACAP-related peptide （PRP） from the brain of largemouth bass （Micropterus salmoides） and used real-time quantitative PCR to detect PRP- PACAP mRNA expression. The PRP-PACAP cDNA has two variants expressed via alternative splicing： a long form, which encodes both PRP and PACAP, and a short form, which encodes only PACAR Sequence analysis results are consistent with a higher conservation of PACAP than PRP peptide sequences. The expression of PACAP-Iong and PACAP-short transcripts was highest in the forebrain, followed by the medulla, midbrain, pituitary, stomach, cerebellum, intestine, and kidney; however, these transcripts were either absent or were weakly expressed in the muscle, spleen, gill, heart, fatty tissue, and liver. The level of PACAP-short transcript expression was significantly higher than expression of the long transcript in the forebrain, cerebella, pituitary and intestine, but lower than that of the long transcript in the stomach. PA CAP- long and PACAP-short transcripts were first detected at the blastula stage of embryogenesis, and the level of expression increased markedly between the muscular contraction stage and 3 d post hatch （dph）. The expression of PACAP-long and PACAP-short transcripts decreased significantly in the brain following 4 d fasting compared with the control diet group. The down-regulation effect was enhanced as fasting continued. Conversely, expression levels increased significantly after 3 d of re-feeding. Our results suggest that PRP- PA CAP acts as an important factor in appetite regulation in largemouth bass.

Possible key residues that determine left gastric artery blood flow response to PACAP in dogs

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.

Low-power laser irradiation inhibits arecoline-induced fibrosis:an in vitro study

Oral submucous fibrosis （OSF） is a potentially malignant disorder that is characterized by a progressive fibrosis in the oral submucosa. Arecoline, an alkaloid compound of the areca nut, is reported to be a major aetiological factor in the development of OSF. Low-power laser irradiation （LPLI） has been reported to be beneficial in fibrosis prevention in different damaged organs. The aim of this study was to investigate the potential therapeutic effects of LPLI on arecoline-induced fibrosis. Arecoline- stimulated human gingival fibroblasts （HGFs） were treated with or without LPLI. The expression levels of the fibrotic marker genes alpha-smooth muscle actin （a-SMA） and connective tissue growth factor （CTGF/CCN2） were analysed by quantitative real- time reverse transcription polymerase chain reaction （RT-PCR） and western blots. In addition, the transcriptional activity of CCN2 was further determined by a reporter assay. The results indicated that arecoline increased the messenger RNA and protein expression of CCN2 and a-SMA in HGF. Interestingly, both LPLI and forskolin, an adenylyl cyclase activator, reduced the expression of arecoline-mediated fibrotic marker genes and inhibited the transcriptional activity of CCN2. Moreover, pretreatment with SQ22536, an adenylyl cyclase inhibitor, blocked LPLI＇s inhibition of the expression of arecoline-mediated fibrotic marker genes. Our data suggest that LPLI may inhibit the expression of arecoline-mediated fibrotic marker genes via the cAMP signalling pathway.

Efficient production of cyclic adenosine monophosphate from adenosine triphosphate by the N-terminal half of adenylate cyclase from Escherichia coli

In this study,we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate(c AMP)from adenosine triphosphate(ATP).First,adenylate cyclase from Escherichia coli MG1655(EAC)and Bordetella Pertussis(BAC)were expressed in E.coli BL21(DE3)and comparatively analyzed for their activities.As a result,EAC from E.coli MG1655 exhibited a higher activity.However,amount of EAC were obtained in an insoluble form.Therefore,we expressed the first 446 amino acids of EAC(EAC446)to avoid the inclusion body.The effects of induction temperature,incubation time,and incubation p H were further evaluated to improve the expression of EAC446.Subsequently,the reaction process for the production of c AMP with ATP as a starting material was investigated.As none of c AMP was detected in the whole-cell based biocatalytic process,the reaction catalyzed by the crude enzyme was determined for c AMP production.What's more,the reaction temperature,reaction p H,metal ion additives and substrate concentration was optimized,and the maximum c AMP production of 18.45 g·L^-1was achieved with a yield of 95.4%after bioconversion of 6 h.

Effects of Activated ACM on Expression of Signal Transducers in Cerebral Cortical Neurons of Rats

To explore the roles of astrocytes in the epileptogenesis, astrocytes and neurons were isolated, purified and cultured in vitro from cerebral cortex of rats. The astrocytes were activated by ciliary neurotrophic factor (CNTF) and astrocytic conditioned medium (ACM) was collected to treat neurons for 4, 8 and 12 h. By using Western blot, the expression of calmodulin dependent protein kinase Ⅱ (CaMKⅡ), inducible nitric oxide synthase (iNOS) and adenylate cyclase (AC) was de- tected in neurons. The results showed that the expression of CaMKⅡ, iNOS and AC was increased significantly in the neurons treated with ACM from 4 h to 12 h (P<0.05), and that of iNOS and AC peaked at 8 h and 12 h respectively. It was suggested that there might be some epileptogenic factors in the ACM and such signal pathways as NOS-NO-cGMP, Ca2+?CaM-CaMKⅡ and AC-cAMP-PKA might take part in the signal transduction of epileptogenesis.

Adenylate cyclase activator forskolin alleviates intracerebroventricular propionic acid-induced mitochondrial dysfunction of autistic rats

Neuronal mitochondrial dysfunction increases inflammatory mediators and leads to free radical generation and anti-oxidant enzymatic alterations,which are major neuropathological hallmarks responsible for autism.Mitochondrial dysfunction in autism is associated with decreased ATP levels due to reduced levels of cyclic adenosine monophosphate.Rat models of autism were established by intracerebroventricular injection of propionic acid.These rat models had memory dysfunction,decreased muscle coordination and gait imbalance.Biochemical estimation of propionic acid-treated rats showed changes in enzyme activity in neuronal mitochondrial electron transport chain complexes and increases in pro-inflammatory cytokines,oxidative stress and lipid biomarkers.Oral administration of 10,20 and 30 mg/kg adenylate cyclase activator forskolin for 15 days reversed these changes in a dose-dependent manner.These findings suggest that forskolin can alleviate neuronal mitochondrial dysfunction and improve neurological symptoms of rats with autism.This study was approved by the RITS/IAEC,SIRSA,HARYANA on March 3,2014(approval No.RITS/IAEC/2014/03/03).

Ecto-F_1-ATPase: A moonlighting protein complex and an unexpected apoA-I receptor

Mitochondrial ATP synthase has been recently detected at the surface of different cell types, where it is a high affinity receptor for apoA-I, the major protein component in high density lipoproteins (HDL). Cell surface ATP synthase (namely ecto-F1-ATPase) expression is related to different biological effects, such as regulation of HDL uptake by hepatocytes, endothelial cell proliferation or antitumor activity of Vγ9/Vδ2 T lymphocytes. This paper reviews the recently discovered functions and regulations of ecto-F1-ATPase. Particularly, the role of the F1-ATPase pathway(s) in HDL-cholesterol uptake and apoA-Imediated endothelial protection suggests its potential importance in reverse cholesterol transport and its regulation might represent a potential therapeutic target for HDL-related therapy for cardiovascular diseases. Therefore, it is timely for us to better understand how this ecto-enzyme and downstream pathways are regulated and to develop pharmacologic interventions.

SPOC domain-containing protein 1 regulates the proliferation and apoptosis of human spermatogonial stem cells through adenylate kinase 4

BACKGROUND Spermatogonial stem cells(SSCs)are the origin of male spermatogenesis,which can reconstruct germ cell lineage in mice.However,the application of SSCs for male fertility restoration is hindered due to the unclear mechanisms of proliferation and self-renewal in humans.AIM To investigate the role and mechanism of SPOC domain-containing protein 1(SPOCD1)in human SSC proliferation.METHODS We analyzed publicly available human testis single-cell RNA sequencing(RNAseq)data and found that SPOCD1 is predominantly expressed in SSCs in the early developmental stages.Small interfering RNA was applied to suppress SPOCD1 expression to detect the impacts of SPOCD1 inhibition on SSC proliferation and apoptosis.Subsequently,we explored the target genes of SPOCD1 using RNA-seq and confirmed their role by restoring the expression of the target genes.In addition,we examined SPOCD1 expression in some non-obstructive azoospermia(NOA)patients to explore the correlation between SPOCD1 and NOA.RESULTS The uniform manifold approximation and projection clustering and pseudotime analysis showed that SPOCD1 was highly expressed in the early stages of SSC,and immunohistological results showed that SPOCD1 was mainly localized in glial cell line-derived neurotrophic factor family receptor alpha-1 positive SSCs.SPOCD1 knockdown significantly inhibited cell proliferation and promoted apoptosis.RNA-seq results showed that SPOCD1 knockdown significantly downregulated genes such as adenylate kinase 4(AK4).Overexpression of AK4 in SPOCD1 knockdown cells partially reversed the phenotypic changes,indicating that AK4 is a functional target gene of SPOCD1.In addition,we found a significant downregulation of SPOCD1 expression in some NOA patients,suggesting that the downregulation of SPOCD1 may be relevant for NOA.CONCLUSION Our study broadens the understanding of human SSC fate determination and may offer new theories on the etiology of male infertility.

Adenyl cyclase activator forskolin protects against Huntington's disease-like neurodegenerative disorders

Long term suppression of succinate dehydrogenase by selective inhibitor 3-nitropropionic acid has been used in rodents to model Huntington＇s disease where mitochondrial dysfunction and oxidative damages are primary pathological hallmarks for neuronal damage. Improvements in learning and memory abilities, recovery of energy levels, and reduction of excitotoxicity damage can be achieved through activation of Adenyl cyclase enzyme by a specific phytochemical forskolin. In this study, intraperitoneal administration of 10 mg/kg 3-nitropropionic acid for 15 days in rats notably reduced body weight, worsened motor cocordination（grip strength, beam crossing task, locomotor activity）, resulted in learning and memory deficits, greatly increased acetylcholinesterase, lactate dehydrogenase, nitrite, and malondialdehyde levels, obviously decreased adenosine triphosphate, succinate dehydrogenase, superoxide dismutase, catalase, and reduced glutathione levels in the striatum, cortex and hippocampus. Intragastric administration of forskolin at 10, 20, 30 mg/kg dose-dependently reversed these behavioral, biochemical and pathological changes caused by 3-nitropropionic acid. These results suggest that forskolin exhibits neuroprotective effects on 3-nitropropionic acid-induced Huntington＇s disease-like neurodegeneration.

Effects of pituitary adenylate cyclase activating polypeptide on CD4^+/CD8^+T cell levels after traumatic brain injury in a rat model

BACKGROUND： The effect of pituitary adenylate cyclase activating polypeptide （PACAP） during traumatic brain injury （TBI） and whether it can modulate secondary injury has not been reported previously. The present study evaluated the potential protective effects of ventricular infusion of PACAP in a rat model of TBI.METHODS： Male Sprague Dawley rats were randomly divided into 3 treatment groups （n=6, each）： sham-operated, vehicle （normal saline）＋TBI, and PACAP＋TBI. Normal saline or PACAP （1 μg/5 μL） was administered intracerebroventricularly 20 minutes before TBI. Right parietal cortical contusion was produced via a weight-dropping method. Brains were extracted 24 hours after trauma. Histological changes in brains were examined by HE staining. The numbers of CD4＋ and CD8＋ T cells in blood and the spleen were detected via flow cytometry.RESULTS： In injured brain regions, edema, hemorrhage, inflammatory cell infiltration, and swollen and degenerated neurons were observed under a light microscope, and the neurons were disorderly arrayed in the hippocampi. Compared to the sham group, average CD4＋ CD8＋ lymphocyte counts in blood and the spleen were significantly decreased in rats that received TBl＋vehicle, and CD4- CD8＋ were increased. In rats administered PACAP prior to TBI, damage was attenuated as evidenced by significantly increased CD4＋, and decreased CD8＋, T lymphocytes in blood and the spleen.CONCLUSION： Pretreatment with PACAP may protect against TBI by influencing periphery T cellular immune function.

Potential PET Ligands for Imaging of Cerebral VPAC and PAC Receptors: Are Non-Peptide Small Molecules Superior to Peptide Compounds?

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) have been known for decades to mediate neuroendocrine and vasodilative actions via G-protein-coupled receptors of Class B. These are targets of imaging probes for positron emission tomography (PET) or single photon emission tomography (SPECT) in tumor diagnostics and tumor grading. However, they play only a subordinate role in the development of tracers for brain imaging. Difficulties in development of non-peptide ligands typical for cerebral receptors of PACAP and VIP are shared by all members of Class B receptor family. Essential landmarks have been confirmed for understanding of structural details of Class B receptor molecular signalling during the last five years. High relevance in the explanation of problems in ligand development for these receptors is admitted to the large N-terminal?ectodomain markedly different from Class A receptor binding sites and poorly suitable as orthosteric binding sites for the most small-molecule compounds. The present study is focused on the recently available receptor ligands for PAC1, VPAC1 and VPAC2 receptors as well as potential small-molecule lead structures suitable for use in PET or SPECT. Recently, biaryl, cyanothiophene and pentanamide structures with affinities in nM-range have been proposed as non-peptide ligands at VPAC1 and VPAC2 receptors. However, most of these ligands have been classified as non-competitive related to the orthosteric binding site of endogenous peptide ligands of VPAC receptors. For PAC1 receptors have been identified hydrazide compounds for which an inhibitory and potentially competitive mechanism of receptor binding has been postulated based on molecular docking studies.

Determining relaxin-3/RXFP3 activation by inhibition of forskolin induced cAMP assay

OBJECTIVE Relaxin-3 is a novel neuropeptide of the relaxin insulin family of peptides.So far,many studies have reported the role of relaxin-3/RXFP3 system in regulating feeding,stress response and cognition.In previous studies using RXFP3 stable cell lines,inhibition of adenylate cyclase by the activation of Gi/o proteins have been reported.Based on this signaling event,we have developed inhibition of forskolin induced cAMP assay to detect RXFP3 activation or inhibition by its agonists or antagonists.METHODS To detect inhibition of adenylate cyclase up on RXFP3 activation by human relaxin-3(H3relaxin),HEK-RXFP3,CHO-RXFP3,SN56 and GT1-7cells were plated in poly-L-lysine coated 24 well plates.The following day,the cells were starved in serum free cell culture media for 6h.Next,cells were treated in triplicate with serum free media(control)and H3 relaxin for 5-15 min.Then,the cells were treated with serum free media with DMSO(control)or forskolin(5-100μmol·L-1)for 15 min at 37℃ with 5%CO2.At the end of the incubation,cell culture media was discarded and the cells were lysed with 0.1mol·L-1 HCl.The cAMP concentration in each lysate was detected by ELISA(Cayman Chemicals).The data from three experiments were analysed using one way ANOVA followed by Bonferroni post hoc test or Dunnett′s post hoc test.RESULTS In CHO-RXFP3 and HEK-RXFP3 cells,10nmol·L-1 of H3 relaxin was able to significantly inhibit the forskolin(5μmol·L-1)induced cAMP levels(P<0.05).In SN56 neuronal like cell line endogenously expressing RXFP3,100nmol·L-1 H3 relaxin was able to significantly reduce forskolin(3μmol·L-1)induced cAMP(P<0.05).However,in wild type HEK293 Tand CHO-K1 cells,10n mol·L-1 H3 relaxin was not able to significantly reduce the forskolin 22(5μmol·L-1)induced cAMP levels.In GT1-7 mouse hypothalamic cells endogenously expressing RXFP3,100nmol·L-1 H3 relaxin and 5or 3μmol·L-1 forskolin,was able toa significantly increase cAMP levels(P<0.05).CONCLUSION Inhibition of forskolin induced cAMP assay can be used to detect Gi/o mediated cAMP inhibition related signaling events due to RXFP3 activation by its agonists in CHO-RXFP3,HEK-RXFP3 and SN56 cell lines.