Gut-derived metabolite 3-methylxanthine enhances cisplatin-induced apoptosis via dopamine receptor D1 in a mouse model of ovarian cancer.

Platinum-based chemotherapy failure represents a significant challenge in the management of ovarian cancer (OC) and contributes to disease recurrence and poor prognosis. Recent studies have shed light on the involvement of the gut microbiota in modulating anticancer treatments. However, the precise underlying mechanisms, by which gut microbiota regulates the response to platinum-based therapy, remain unclear. Here, we investigated the role of gut microbiota on the anticancer response of cisplatin and its underlying mechanisms. Our results demonstrate a substantial improvement in the anticancer efficacy of cisplatin following antibiotic-induced perturbation of the gut microbiota in OC-bearing mice. 16S rRNA sequencing showed a pronounced alteration in the composition of the gut microbiome in the cecum contents following exposure to cisplatin. Through metabolomic analysis, we identified distinct metabolic profiles in the antibiotic-treated group, with a notable enrichment of the gut-derived metabolite 3-methylxanthine in antibiotic-treated mice. Next, we employed a strategy combining transcriptome analysis and chemical-protein interaction network databases. We identified metabolites that shared structural similarity with 3-methylxanthine, which interacted with genes enriched in cancer-related pathways. It is identified that 3-methylxanthinesignificantly enhances the effectiveness of cisplatin by promoting apoptosis both in vivo and in vitro. Importantly, through integrative multiomics analyses, we elucidated the mechanistic basis of this enhanced apoptosis, revealing a dopamine receptor D1-dependent pathway mediated by 3-methylxanthine. This study elucidated the mechanism by which gut-derived metabolite 3-methylxanthine mediated cisplatin-induced apoptosis. Our findings highlight the potential translational significance of 3-methylxanthine as a promising adjuvant in conjunction with cisplatin, aiming to improve treatment outcomes for OC patients.IMPORTANCEThe precise correlation between the gut microbiota and the anticancer effect of cisplatin in OC remains inadequately understood. Our investigation has revealed that manipulation of the gut microbiota via the administration of antibiotics amplifies the efficacy of cisplatin through the facilitation of apoptosis in OC-bearing mice. Metabolomic analysis has demonstrated that the cecum content from antibiotic-treated mice exhibits an increase in the levels of 3-methylxanthine, which has been shown to potentially enhance the therapeutic effectiveness of cisplatin by an integrated multiomic analysis. This enhancement appears to be attributable to the promotion of cisplatin-induced apoptosis, with 3-methylxanthine potentially exerting its influence via the dopamine receptor D1-dependent pathway. These findings significantly contribute to our comprehension of the impact of the gut microbiota on the anticancer therapy in OC. Notably, the involvement of 3-methylxanthine suggests its prospective utility as a supplementary component for augmenting treatment outcomes in patients afflicted with ovarian cancer.

Evaluation of glomerular hemodynamic changes by sodium-glucose-transporter 2 inhibition in type 2 diabetic rats using in vivo imaging.

The mechanisms responsible for glomerular hemodynamic regulation with sodium-glucose co-transporter 2 (SGLT2) inhibitors in kidney disease due to type 2 diabetes remain unclear. Therefore, we investigated changes in glomerular hemodynamic function using an animal model of type 2 diabetes, treated with an SGLT2 inhibitor alone or in combination with a renin-angiotensin-aldosterone system inhibitor using male Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats. Afferent and efferent arteriolar diameter and single-nephron glomerular filtration rate (SNGFR) were evaluated in ZDF rats measured at 0, 30, 60, 90, and 120 minutes after the administration of a SGLT2 inhibitor (luseogliflozin). Additionally, we assessed these changes under the administration of the adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine), along with coadministration of luseogliflozin and an angiotensin II receptor blocker (ARB), telmisartan. ZDF rats had significantly increased SNGFR, and afferent and efferent arteriolar diameters compared to ZL rats, indicating glomerular hyperfiltration. Administration of luseogliflozin significantly reduced afferent vasodilatation and glomerular hyperfiltration, with no impact on efferent arteriolar diameter. Urinary adenosine levels were increased significantly in the SGLT2 inhibitor group compared to the vehicle group. A1aR antagonism blocked the effect of luseogliflozin on kidney function. Co-administration of the SGLT2 inhibitor and ARB decreased the abnormal expansion of glomerular afferent arterioles, whereas the efferent arteriolar diameter was not affected. Thus, regulation of afferent arteriolar vascular tone via the A1aR pathway is associated with glomerular hyperfiltration in type 2 diabetic kidney disease.

Optimizing myocardial cell protection with xanthine derivative KMUP-3 potentiates autophagy through the PI3K/Akt/eNOS axis.

BACKGROUND: Autophagy can have either beneficial or detrimental effects on various heart diseases. Pharmacological interventions improve cardiac function, which is correlated with enhanced autophagy. To assess whether a xanthine derivative (KMUP-3) treatment coincides with enhanced autophagy while also providing cardio-protection, we investigated the hypothesis that KMUP-3 treatment activation of autophagy through PI3K/Akt/eNOS signalling offered cardioprotective properties. METHODS: The pro-autophagic effect of KMUP-3 was performed in a neonatal rat model targeting cardiac fibroblasts and cardiomyocytes, and by assessing the impact of KMUP-3 treatment on cardiotoxicity, we used antimycin A-induced cardiomyocytes. RESULTS: As determined by transmission electron microscopy observation, KMUP-3 enhanced autophagosome formation in cardiac fibroblasts. Furthermore, KMUP-3 significantly increased the expressions of autophagy-related proteins, LC3 and Beclin-1, both in a time- and dose-dependent manner; moreover, the pro-autophagy and nitric oxide enhancement effects of KMUP-3 were abolished by inhibitors targeting eNOS and PI3K in cardiac fibroblasts and cardiomyocytes. Notably, KMUP-3 ameliorated cytotoxic effects induced by antimycin A, demonstrating its protective autophagic response. CONCLUSION: These findings enable the core pathway of PI3K/Akt/eNOS axis in KMUP-3-enhanced autophagy activation and suggest its principal role in safeguarding against cardiotoxicity.

Synthesis and Medicinal Applications of N-Heterocyclic Carbene Complexes Based on Caffeine and Other Xanthines.

Xanthines are purine derivatives predominantly found in plants. These include compounds such as caffeine, theophylline, and theobromine and exhibit a variety of pharmacological properties, demonstrating efficacy in treating neurodegenerative disorders, respiratory dysfunctions, and also cancer. The versatile attributes of these materials render them privileged scaffolds for the development of compounds for various biological applications. Xanthines are N-heterocyclic carbene precursors that combine a pyrimidine and an imidazole ring. Owing to their biological relevance, xanthines have been employed as N-heterocyclic carbenes in the development of metallodrugs for anticancer and antimicrobial purposes. In this conceptual review, we examine key examples of N-heterocyclic carbene complexes derived from caffeine and other xanthines, elucidating their synthetic methods and describing their pertinent medicinal applications.

Involvement of adenosine A1 receptor in electroacupuncture-mediated inhibition of astrocyte activation during neuropathic pain / Envolvimento do receptor de adenosina A1 na inibição da ativação de astrócitos mediada por eletroacupuntura durante a dor neuropática

ABSTRACT Neuropathic pain is a chronic pain condition caused by damage or dysfunction of the central or peripheral nervous system. Electroacupuncture (EA) has an antinociceptive effect on neuropathic pain, which is partially due to inhibiting astrocyte activation in the spinal cord. We found that an intrathecal injection of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective adenosine A1 receptor antagonist, reversed the antinociceptive effects of EA in a chronic constriction injury-induced neuropathic pain model. The expression of GFAP in L4-L6 spinal cord was significantly upgraded, while DPCPX suppressed the effect of the EA-mediating inhibition of astrocyte activation, as well as wiping out the EA-induced suppression of cytokine content (TNF-α). These results indicated that the adenosine A1 receptor is involved in EA actions during neuropathic pain through suppressing astrocyte activation as well as TNF-α upregulation of EA, giving enlightenment to the mechanisms of acupuncture analgesia and development of therapeutic targets for neuropathic pain.

RESUMO A dor neuropática é uma condição de dor crônica causada por dano ou disfunção do sistema nervoso central ou periférico. A eletroacupuntura (EA) tem um efeito antinociceptivo durante a dor neuropática, que é parcialmente devido à inibição da ativação de astrócitos na medula espinhal. Descobrimos que a injeção intratecal de 8-ciclopentil-1,3-dipropilxantina (DPCPX), um antagonista seletivo do receptor de adenosina A1, reverteu os efeitos antinociceptivos da EA no modelo de dor neuropática induzida por lesão por constrição crônica (CCI). A expressão da GFAP na medula espinal L4-L6 foi significativamente melhorada, enquanto a DPCPX suprimiu o efeito da inibição mediadora da EA na ativação de astrócitos, bem como eliminou a supressão induzida pela EA do conteúdo de citocina (TNF-α). Esses resultados indicam que o receptor de adenosina A1 está envolvido nas ações da EA durante a dor neuropática, suprimindo a ativação astrocitária, bem como o aumento da TNF-α na EA, fornecendo esclarecimentos sobre os mecanismos de analgesia da acupuntura e o desenvolvimento de alvos terapêuticos para dor neuropática.

Propentofylline reduces glial scar development following gliotoxic damage in the rat brainstem / Propentofilina reduz o desenvolvimento da cicatriz glial após dano gliotóxico no tronco encefálico de ratos

ABSTRACT Propentofylline is a xanthine derivative that depresses activation of glial cells, whose responses contribute to neural tissue damage during inflammation. Ethidium bromide injection into the central nervous system induces local oligodendroglial and astrocytic loss, resulting in primary demyelination, neuroinflammation and blood-brain barrier disruption. Surviving astrocytes present a vigorous reaction around the injury site with increased immunoreactivity to glial fibrillary acidic protein (GFAP). Objective This study aimed to evaluate the effect of propentofylline administration on astrocytic response following gliotoxic injury. Method Wistar rats were injected with ethidium bromide into the cisterna pontis and treated or not with propentofylline (12.5mg/kg/day, intraperitoneal) during the experimental period. Brainstem sections were collected from 15 to 31 days after gliotoxic injection and processed for GFAP immunohistochemistry. Results and Conclusion Results demonstrate that propentofylline decreased astrocytic activation until the 21st day, suggesting that this drug may have a role in reducing glial scar development following injury.

RESUMO A propentofilina é uma xantina que deprime a ativação das células gliais, cujas respostas contribuem para o dano neural durante inflamação. A injeção de brometo de etídio no sistema nervoso central induz a perda oligodendroglial e astrocitária, resultando em desmielinização, neuroinflamação e ruptura da barreira hematoencefálica. Os astrócitos sobreviventes apresentam vigorosa reação ao redor da lesão com aumento da imunorreatividade à proteína glial fibrilar ácida (GFAP). Objetivo Este estudo objetivou avaliar o efeito da propentofilina sobre a resposta astrocitária após injúria gliotóxica. Método Ratos Wistar foram injetados com brometo de etídio na cisterna basal e tratados ou não com propentofilina (12.5mg/kg/dia, intraperitoneal). Amostras do tronco encefálico foram coletadas dos 15 aos 31 dias pós-injeção do gliotóxico e processadas para estudo ultraestrutural e imuno-histoquímico para GFAP. Resultados e Conclusão Os resultados demonstram que a propentofilina reduziu a ativação astrocitária até o 21o dia, sugerindo que essa droga pode atuar na redução da cicatriz glial após injúria.

Propentofylline reverses delayed remyelination in streptozotocin-induced diabetic rats

Objective The diabetic state induced by streptozotocin injection is known to impair oligodendroglial remyelination in the rat brainstem following intracisternal injection with the gliotoxic agent ethidium bromide (EB). In such experimental model, propentofylline (PPF) recently showed to improve myelin repair, probably due to its neuroprotective, antiinflammatory and antioxidant effects. The aim of this study was to evaluate the effect of PPF administration in diabetic rats submitted to the EB-demyelinating model. Materials and methods Adult male rats, diabetic or not, received a single injection of 10 microlitres of 0.1% EB solution into the cisterna pontis. For induction of diabetes mellitus the streptozotocin-diabetogenic model was used (50 mg/kg, intraperitoneal route – IP). Some diabetic rats were treated with PPF (12.5 mg/kg/day, IP route) during the experimental period. The animals were anesthetized and perfused from 7 to 31 days after EB injection and brainstem sections were collected for analysis of the lesions by light and transmission electron microscopy. Results Diabetic rats injected with EB showed larger amounts of myelin-derived membranes in the central areas of the lesions and considerable delay in the remyelinating process played by surviving oligodendrocytes and invading Schwann cells after the 15th day. On the other hand, diabetic rats that received PPF presented lesions similar to those of non-diabetic animals, with rapid remyelination at the edges of the lesion site and fast clearance of myelin debris from the central area. Conclusion The administration of PPF apparently reversed the impairment in remyelination induced by the diabetic state. Arch Endocrinol Metab. 2015;59(1):47-53 .

Antidipsogenic effects of central adenosine-5'-triphosphate

Besides other physiological functions, adenosine-5'-triphosphate (ATP) is also a neurotransmitter that acts on purinergic receptors. In spite of the presence of purinergic receptors in forebrain areas involved with fluid-electrolyte balance, the effect of ATP on water intake has not been investigated. Therefore, we studied the effects of intracerebroventricular (icv) injections of ATP (100, 200 and 300 nmol/µL) alone or combined with DPCPX or PPADS (P1 and P2 purinergic antagonists, respectively, 25 nmol/µL) on water intake induced by water deprivation. In addition, the effect of icv ATP was also tested on water intake induced by intragastric load of 12 percent NaCl (2 mL/rat), acute treatment with the diuretic/natriuretic furosemide (20 mg/kg), icv angiotensin II (50 ng/µL) or icv carbachol (a cholinergic agonist, 4 nmol/µL), on sodium depletion-induced 1.8 percent NaCl intake, and on food intake induced by food deprivation. Male Holtzman rats (280-320 g, N = 7-11) had cannulas implanted into the lateral ventricle. Icv ATP (300 nmol/µL) reduced water intake induced by water deprivation (13.1 ± 1.9 vs saline: 19.0 ± 1.4 mL/2 h; P < 0.05), an effect blocked by pre-treatment with PPADS, but not DPCPX. Icv ATP also reduced water intake induced by NaCl intragastric load (5.6 ± 0.9 vs saline: 10.3 ± 1.4 mL/2 h; P < 0.05), acute furosemide treatment (0.5 ± 0.2 vs saline: 2.3 ± 0.6 mL/15 min; P < 0.05), and icv angiotensin II (2.2 ± 0.8 vs saline: 10.4 ± 2.0 mL/2 h; P < 0.05), without changing icv carbachol-induced water intake, sodium depletion-induced 1.8 percent NaCl intake and food deprivation-induced food intake. These data suggest that central ATP, acting on purinergic P2 receptors, reduces water intake induced by intracellular and extracellular dehydration.