RESUMO
Small fruits such as strawberries, are a good source of natural antioxidants. In recent decades, many efforts have been made to increase the shelf life of strawberries and maintain its nutritional value in post-harvest conditions. In the present study, the effects of spermine (Spm) and spermidine (Spd) (0, 1.0 and 1.5 mM) on the post-harvest life and quality of strawberry fruits during the 3rd, 6th, and 12th days of storage, were investigated. Applications of Spm and Spd decreased the rate of weight loss, fruit decay, soluble solids content, fruit juice pH and taste index during the storage period in compared to the control. However, titratable acids and vitamin C contents, tissue stiffness, phenolic compounds and antioxidant activity increased in compared to the control. These growth regulators prevented the aging and loss of bioactive compounds of the fruit by increasing the antioxidant activity and preventing the destruction of the fruit tissue. Among the studied treatments, applications of 1.5 mM of Spm and Spd were the most effective treatments to enhance the storage life and quality characters of strawberry fruits.
Assuntos
Fragaria , Espermidina , Espermidina/farmacologia , Espermidina/análise , Espermina/farmacologia , Espermina/análise , Antioxidantes/farmacologia , Antioxidantes/análise , FrutasRESUMO
The role of the calcium-permeable AMPA receptor (CP-AMPAR) in synaptic plasticity is well established. CP-AMPAR is believed to be recruited to synapse when the memory trace is in a plastic state; however, the direct implications of its expression for memory processes is less known. Here, we investigated the contribution of CP-AMPAR expressed in the basolateral amygdala (BLA) and hippocampus (HPC) in consolidation of different types of memory, retrieval and memory update. We showed that CP-AMPAR blockade by NASPM in the BLA and HPC impaired fear memory consolidation. NASPM infusion in the HPC also impaired spatial memory consolidation in the water maze, whereas consolidation of object location memory was not affected. We found evidence of the CP-AMPAR involvement in the BLA and in the HPC upon memory retrieval. Furthermore, memory update was affected by NASPM infusion in the HPC in both immediate shock deficit and water maze reversal learning tasks. Our data indicate that the activity of CP-AMPAR in the BLA and HPC is required for the consolidation of emotional memories. Moreover, this receptor activity is required for memory retrieval in the BLA and HPC. These findings support that CP-AMPAR has a key function in memory states in which plastic changes are presumably higher, such as the beginning of memory consolidation, and retrieval-induced updating.
Assuntos
Consolidação da Memória/fisiologia , Rememoração Mental/fisiologia , Receptores de AMPA/metabolismo , Animais , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Complexo Nuclear Basolateral da Amígdala/metabolismo , Cálcio/metabolismo , Antagonistas de Aminoácidos Excitatórios/farmacologia , Medo/efeitos dos fármacos , Medo/fisiologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Consolidação da Memória/efeitos dos fármacos , Rememoração Mental/efeitos dos fármacos , Ratos Wistar , Receptores de AMPA/antagonistas & inibidores , Reversão de Aprendizagem/efeitos dos fármacos , Reversão de Aprendizagem/fisiologia , Memória Espacial/efeitos dos fármacos , Memória Espacial/fisiologia , Espermina/análogos & derivados , Espermina/farmacologiaRESUMO
Lipopolysaccharide (LPS) has been long known to promote neuroinflammation and learning and memory deficits. Since spermine, one of the main natural polyamines in the central nervous system, protects from LPS-induced memory deficit by a mechanism that comprises GluN2B receptors, the aim of the present study was to determine whether brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB) receptor and cAMP response element binding (CREB) are involved in this protective effect of spermine. Adult male Swiss albino mice received, immediately after training in the novel object recognition task, saline or LPS (250⯵g/kg, i.p.); 5â¯min later they received saline or spermine (0.3â¯mg/kg, i.p.) and, when specified, 5â¯min thereafter saline or the TrkB receptor antagonist ANA-12 (0.5â¯mg/kg, i.p.) in different flanks. Animals were tested 24â¯h after training. Spermine protected from LPS-induced memory deficit and this protective effect was reversed by ANA-12. In a subset of animals BDNF, CREB and phospho-CREB immunoreactivity was determined in the hippocampi and cerebral cortex 4â¯h after spermine injection. Spermine reversed the decrease of mature BDNF levels induced by LPS in both hippocampus and cerebral cortex. Spermine increased phospho-CREB content and phospho-CREB/total CREB ratio in the cerebral cortex of LPS-treated mice. The results support that the protective effect of spermine on LPS-induced memory deficits depends on TrkB receptor activation and is accompanied by restoration of mature BDNF levels in hippocampus and cerebral cortex, as well as increased CREB phosphorylation in the cerebral cortex.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Hipocampo/efeitos dos fármacos , Glicoproteínas de Membrana/metabolismo , Transtornos da Memória/metabolismo , Fármacos Neuroprotetores/farmacologia , Proteínas Tirosina Quinases/metabolismo , Espermina/farmacologia , Animais , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Hipocampo/metabolismo , Lipopolissacarídeos , Masculino , Transtornos da Memória/induzido quimicamente , Camundongos , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacosRESUMO
Aiming to clarify the mechanism of inhibition of (Na+, K+)-ATPase activity by polyamines, we examined the effects of exogenous putrescine, spermidine, and spermine on the kinetic behavior of phosphoenzyme-linked partial reactions using a microsomal gill (Na+, K+)-ATPase from juvenile and adult M. amazonicum, a freshwater palaemonid shrimp. The time course of phosphointermediate formation is greater (0.089 ± 0.006 s-1) in adults than in juveniles (0.053 ± 0.003 s-1) for spermidine, but similar to juveniles (0.059 ± 0.004 s-1) for putrescine. Maximum phosphointermediate formation for the (Na+, K+)-ATPase from juveniles decreased by 46% and 32% with spermidine and putrescine, respectively. In adults, maximum phosphointermediate levels decreased by 50% and 8%, respectively. For both spermidine and putrescine, dephosphorylation rates were higher for adults than for juveniles, and were higher than in controls without polyamines. Spermine had a negligible effect (<10%) on phosphorylation/dephosphorylation rates of both juvenile and adult enzymes. This is the first report on the effects of polyamines on phosphoenzyme-linked partial reactions in juvenile and adult M. amazonicum gill (Na+, K+)-ATPases. Our findings suggest that the phosphorylation/dephosphorylation steps of this gill enzyme may be regulated by polyamines during ontogenetic development.
Assuntos
Brânquias/enzimologia , Palaemonidae/enzimologia , Poliaminas/farmacologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Brânquias/efeitos dos fármacos , Cinética , Palaemonidae/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Putrescina/farmacologia , Espermidina/farmacologia , Espermina/farmacologiaRESUMO
In this work we have characterized the effects of the intercalator ethidium bromide (EtBr) on the DNA condensation process by using force spectroscopy and gel electrophoresis. We have tested two condensing agents: spermine (spm(4+)), a tetravalent cationic amine which promotes cation-induced DNA condensation, and poly(ethylene glycol) (PEG), a neutral polymer which promotes DNA ψ-condensation. Two different types of experiments were performed. In the first type, bare DNA molecules disperse in solution are first treated with EtBr for intercalation, and then the condensing agent is added to the sample with the purpose of verifying the effects of the intercalator in hindering DNA condensation. In the second experiment type, the bare DNA molecules are first condensed, and then the intercalator is added to the sample in order to verify its influence on the previously condensed DNA. The results obtained with the two different experimental techniques used agree very well, indicating that previously intercalated EtBr can hinder both cation-induced and ψ-condensation, being more efficient in the first case. On the other hand, EtBr has little effect on the previously formed cation-induced condensates, but is efficient in unfolding the ψ-condensates.
Assuntos
DNA/química , Etídio/farmacologia , Substâncias Intercalantes/farmacologia , Conformação de Ácido Nucleico/efeitos dos fármacos , Polietilenoglicóis/farmacologia , Espermina/farmacologia , Eletroforese , Análise EspectralRESUMO
This work investigated the roles of the tetraamine thermospermine (TSpm) by analysing its contribution to Arabidopsis basal defence against the biotrophic bacterium Pseudomonas viridiflava. The participation of polyamine oxidases (PAOs) in TSpm homeostasis and TSpm-mediated defence was also investigated. Exogenous supply of TSpm, as well as ectopic expression of the TSpm biosynthetic gene ACL5, increased Arabidopsis Col-0 resistance to P. viridiflava, while null acl5 mutants were less resistant than Col-0 plants. The above-mentioned increase in resistance was blocked by the PAO inhibitor SL-11061, thus demonstrating the participation of TSpm oxidation. Analysis of PAO genes expression in transgenic 35S::ACL5 and Col-0 plants supplied with TSpm suggests that PAO 1, 3, and 5 are the main PAOs involved in TSpm catabolism. In summary, TSpm exhibited the potential to perform defensive functions previously reported for its structural isomer Spm, and the relevance of these findings is discussed in the context of ACL5 expression and TSpm concentration in planta. Moreover, this work demonstrates that manipulation of TSpm metabolism modifies plant resistance to pathogens.
Assuntos
Arabidopsis/imunologia , Arabidopsis/microbiologia , Resistência à Doença/imunologia , Doenças das Plantas/microbiologia , Pseudomonas/fisiologia , Espermina/análogos & derivados , Amina Oxidase (contendo Cobre)/antagonistas & inibidores , Amina Oxidase (contendo Cobre)/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Resistência à Doença/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Oxirredução/efeitos dos fármacos , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/antagonistas & inibidores , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Pseudomonas/efeitos dos fármacos , Pseudomonas/crescimento & desenvolvimento , Putrescina/metabolismo , Espermina/metabolismo , Espermina/farmacologia , Poliamina OxidaseRESUMO
OBJECTIVE: The amino acid Arginine (Arg) is the main biological precursor of nitric oxide (NO) and has been described to improve insulin sensitivity in diabetes and obesity. We investigated the molecular mechanisms involved in the long-term effects of Arg on glucose and lipid metabolism. MATERIALS AND METHODS: L6 myotubes were treated with Arg (7 mmol/L) for 6 days. D-Mannitol (7 mmol/L) was used as control; spermine NONOate (10 µmol/L) and L-NAME (100 µmol/L) were used to evaluate the NO/c-GMP pathway role. Basal and insulin-induced (120 nmol/L) glycogen synthesis, glucose uptake and lipid oxidation, c-GMP and nitrite levels, and the intracellular signaling pathways were evaluated. RESULTS: Arg-treatment increased: 1) basal and insulin-stimulated glycogen synthesis; 2) glucose uptake; 3) palmitate oxidation; 4) p-Akt (Ser(473)), total and plasma membrane GLUT4 content, total and p-AMPK-α and p-ACC (Ser(79)), p-GSK-3α/ß (Ser(21/9)) and 5) nitrite and c-GMP levels. L-NAME treatment suppressed Arg effects on: 1) nitrite and c-GMP content; 2) glycogen synthesis and glucose uptake; 3) basal and insulin-stimulated p-Akt (Ser(473)), total and p-AMPK-α and ACC, and nNOS expression. CONCLUSION: We provide evidence that Arg improves glucose and lipid metabolism in skeletal muscle, in parallel with increased phosphorylation of Akt and AMPK-α. These effects were mediated by the NO/c-GMP pathway. Thus, arginine treatment enhances signal transduction and has a beneficial effect of metabolism in skeletal muscle through direct activation of Akt and AMPK pathways.
Assuntos
Glucose/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Espermina/análogos & derivados , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Arginina/antagonistas & inibidores , Arginina/farmacologia , Western Blotting , Linhagem Celular , Transportador de Glucose Tipo 4/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/citologia , Músculo Esquelético/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Transdução de Sinais/efeitos dos fármacos , Espermina/farmacologiaRESUMO
We investigated the effect of the exogenous polyamines spermine, spermidine and putrescine on modulation by ATP, Kâº, Naâº, NH4⺠and Mg²âº and on inhibition by ouabain of posterior gill microsomal Naâº,Kâº-ATPase activity in the blue crab, Callinectes ornatus, acclimated to a dilute medium (21 salinity). This is the first kinetic demonstration of competition between spermine and spermidine for the cation sites of a crustacean Naâº,Kâº-ATPase. Polyamine inhibition is enhanced at low cation concentrations: spermidine almost completely inhibited total ATPase activity, while spermine inhibition attained 58%; putrescine had a negligible effect on Naâº,Kâº-ATPase activity. Spermine and spermidine affected both V and K for ATP hydrolysis but did not affect ouabain-insensitive ATPase activity. ATP hydrolysis in the absence of spermine and spermidine obeyed Michaelis-Menten behavior, in contrast to the cooperative kinetics seen for both polyamines. Modulation of V and K by Kâº, Naâº, NH4⺠and Mg²âº varied considerably in the presence of spermine and spermidine. These findings suggest that polyamine inhibition of Naâº,Kâº-ATPase activity may be of physiological relevance to crustaceans that occupy habitats of variable salinity.
Assuntos
Trifosfato de Adenosina/metabolismo , Braquiúros/enzimologia , Cátions/metabolismo , Brânquias/enzimologia , Poliaminas/farmacologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Ativação Enzimática/efeitos dos fármacos , Brânquias/efeitos dos fármacos , Hidrólise/efeitos dos fármacos , Cinética , Ouabaína/farmacologia , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores , Espermidina/farmacologia , Espermina/farmacologiaRESUMO
Polyamines (putrescine, spermidine and spermine) are important endogenous regulators of ion channels, such as vanilloid (TRPV1), glutamatergic (NMDA or AMPA/kainate) and acid-sensitive (ASIC) receptors. In the present study, we have investigated the possible nociceptive effect induced by polyamines and the mechanisms involved in this nociception in vivo. The subcutaneous (s.c.) injection of capsaicin (as positive control), spermine, spermidine or putrescine produced nociception with ED(50) of 0.16 (0.07-0.39)nmol/paw, 0.4 (0.2-0.7) µmol/paw, 0.3 (0.1-0.9) µmol/paw and 3.2 (0.9-11.5) µmol/paw, respectively. The antagonists of NMDA (MK801, 1 nmol/paw), AMPA/kainate (DNQX, 1 nmol/paw) or ASIC receptors (amiloride, 100 nmol/paw) failed to reduce the spermine-trigged nociception. However, the TRPV1 antagonists capsazepine or SB366791 (1 nmol/paw) reduced spermine-induced nociception, with inhibition of 81 ± 10 and 68 ± 9%, respectively. The previous desensitization with resiniferatoxin (RTX) largely reduced the spermine-induced nociception and TRPV1 expression in the sciatic nerve, with reductions of 82 ± 9% and 67 ± 11%, respectively. Furthermore, the combination of spermine (100 nmol/paw) and RTX (0.005 fmol/paw), in doses which alone were not capable of inducing nociception, produced nociceptive behaviors. Moreover, different concentrations of spermine (3-300 µM) enhanced the specific binding of [(3)H]-RTX to TRPV1 receptor. Altogether, polyamines produce spontaneous nociceptive effect through the stimulation of TRPV1, but not of ionotropic glutamate or ASIC receptors.
Assuntos
Nociceptores/efeitos dos fármacos , Espermina/farmacologia , Canais de Cátion TRPV/efeitos dos fármacos , Canais Iônicos Sensíveis a Ácido , Animais , Poliaminas Biogênicas/farmacologia , Western Blotting , Diterpenos/metabolismo , Diterpenos/farmacologia , Ácido Glutâmico/farmacologia , Masculino , Camundongos , Fibras Nervosas/efeitos dos fármacos , Proteínas do Tecido Nervoso/efeitos dos fármacos , Dor/induzido quimicamente , Dor/prevenção & controle , Medição da Dor/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Receptores de Ácido Caínico/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Canais de Sódio/efeitos dos fármacos , Espermina/administração & dosagemRESUMO
The mechanism whereby extracellular Ca(2+) exerts the endothelium-dependent control of vascular tone is still unclear. In this study, we assessed whether cardiac microvascular endothelial cells (CMEC) express a functional extracellular Ca(2+)-sensing receptor (CaSR) using a variety of techniques. CaSR mRNA was detected using RT-PCR, and CaSR protein was identified by immunocytochemical analysis. In order to assess the functionality of the receptor, CMEC were loaded with the Ca(2+)-sensitive fluorochrome, Fura-2/AM. A number of CaSR agonists, such as spermine, Gd(3+), La(3+) and neomycin, elicited a heterogeneous intracellular Ca(2+) signal, which was abolished by disruption of inositol 1,4,5-trisphosphate (InsP(3)) signaling and by depletion of intracellular stores with cyclopiazonic acid. The inhibition of the Na(+)/Ca(2+) exchanger upon substitution of extracellular Na(+) unmasked the Ca(2+) signal triggered by an increase in extracellular Ca(2+) levels. Finally, aromatic amino acids, which function as allosteric activators of CaSR, potentiated the Ca(2+) response to the CaSR agonist La(3+). These data provide evidence that CMEC express CaSR, which is able to respond to physiological agonists by mobilizing Ca(2+) from intracellular InsP(3)-sensitive stores.