Repercussões metabólicas e uso dos medicamentos sensibilizadores da insulina em mulheres com síndrome dos ovários policísticos / Metabolic repercussions and use of insulin-sensitizing drugs in women with polycystic ovary syndrome

A síndrome dos ovários policísticos (SOP) é um distúrbio endócrino-metabólico muito frequente no período reprodutivo. Quando associado ao distúrbio metabólico, as mulheres com SOP podem ter ainda risco acrescido para doença cardiovascular. O objetivo deste manuscrito é descrever as repercussões metabólicas, incluindo quais as principais, como investigar e as consequências desse distúrbio sobre a saúde da mulher. É uma revisão narrativa mostrando a implicação da resistência insulínica, das dislipidemias e da síndrome metabólica sobre o sistema reprodutor e sobre o risco cardiovascular da mulher com SOP, bem como do uso de sensibilizadores de insulina no seu tratamento. Conclui-se que a correção dos distúrbios metabólicos na SOP é benéfica tanto para o sistema reprodutor quanto para o cardiovascular. A primeira linha de tratamento é a mudança de estilo de vida e a perda de peso. Na resposta inadequada, o tratamento medicamentoso está recomendado. Nas mulheres com obesidade mórbida que não tiveram bons resultados com o tratamento clínico, a cirurgia bariátrica é uma opção.(AU)

Interactions between intracellular Ca2+ stores: Ca2+ released from the NAADP pool potentiates cADPR-induced Ca2+ release

Cells possess multiple intracellular Ca2+-releasing systems. Sea urchin egg homogenates are a well-established model to study intracellular Ca2+ release. In the present study the mechanism of interaction between three intracellular Ca2+ pools, namely the nicotinic acid adenine dinucleotide phosphate (NAADP), the cyclic ADP-ribose (cADPR) and the inositol 1',4',5'-trisphosphate (IP3)-regulated Ca2+ stores, is explored. The data indicate that the NAADP Ca2+ pool could be used to sensitize the cADPR system. In contrast, the IP3 pool was not affected by the Ca2+ released by NAADP. The mechanism of potentiation of the cADPR-induced Ca2+ release, promoted by Ca2+ released from the NAADP pool, is mediated by the mechanism of Ca2+-induced Ca2+ release. These data raise the possibility that the NAADP Ca2+ store may have a role as a regulator of the cellular sensitivity to cADPR

Participation of the phosphoinositide metabolism in the hypersensitive response of Citrus limon against Alternaria alternata

Lemon seedlings inoculated with Alternaria alternata develop a hypersensitive response (HR) that includes the induction of Phenylalanine ammonia-lyase (PAL, E. C. 4.3.1.5) and the synthesis of scoparone. The signal transduction pathway involved in the development of this response is unknown. We used several inhibitors of the Phosphoinositide (PI) animal system to study a possible role of Inositol-1,4,5-triphosphate (IP3) in the transduction of the fungal conidia signal in Citrus limon. The HR was only partially inhibited by EGTA, suggesting that not only external but internal calcium as well are necessary for a complete development of the HR. In this plant system, Alternaria alternata induced an early accumulation of the second messenger IP3. When lemon seedlings were watered long term with LiCl, an inhibitor of the phosphoinositide cycle, the IP3 production was reduced, and the LiCl-watered plants could neither induce PAL nor synthesize scoparone in response to fungal conidia. Furthermore, neomycin, a Phospholipase C (PLC, E. C. 3.1.4.3) inhibitor, also inhibited PAL induction and scoparone synthesis in response to A. alternata. These results suggest that IP3 could be involved in the signal transduction pathway for the development of the HR of Citrus limon against A. alternata.

Liberación anormal de CA²+ inducida por el inositol trifosfato en fibras estriadas susceptibles a hipertermia maligna / Abnormal liberation of CA²+ induced by the triphosphate inositol in striated fibers susceptible to malignant lypetermia

La hipertermia maligna es un síndrome farmocogenético asociado con la alteración de la regulación del calcio mioplásmico. Una modificación en el metabolismo del inositol 1,4,5 trifosfato (InsP3), hasido asociada con la fisiopatología de la hipertermia maligna. El objetivo del trabajo fue estudiar el efecto del InsP3 sobre la concentración intracelular de calcio ([CA²+]i) en fibras musculares obtenidas de sujetos no susceptibles y susceptibles a hipertermia maligna. La [CA²]i fue cuantificada mediante el uso de microelectrodos sensibles a CA²+. En susceptibles a hipertermia maligna la [CA²+]i fue más elevada que en las fibras musculares no suceptibles hipertemia maligna. La microinyección de InsP3 0,5 y 1 µM indujo una elevación significativa de la [CA²+]i, en ambos grupos musculares. Sin embargo, este incremento fue mayor en las fibras susceptibles a hipertermia maligna que en las no susceptibles a hipertermia maligna. La incubación de los músculos en soluciones con bajo contenido en Ca²+ o en nifedipina (10 µM) no modificó la elevación de [Ca²+]i mediana por el InsP3. El tratamiento con dantrolene (50 µM) redujo la [Ca²+]i, y bloqueó la elevación de la [Ca²+]i, inducida por el InsP3 en ambos grupos. Estos resultados sugieren (i) el posible papel del InsP3 como mediador químico en la liberación de Ca²+ desde los depósitos intracelulares; (ii) que el InsP3 podrá jugar un papel importante en la fisiopatología de la hipertermia maligna y (iii) que el efecto profiláctico y terapeútico del dantrolene podría estar relacionado con su efecto inhibitorio sobre la liberación de calcio intracelular mediada por el InsP3

The second messenger for visual excitation in invertebrate phototransduction

Invertebrate visual transduction involves a second messenger cascade process that leads to an increase in membrane conductance. The identity of the second messenger that gates the light-dependent channels is presently a major focus of attention. Cyclic GMP, inositol trisphosphate and Ca2+ are the most likely candidates for being such a messenger in the species studied so far. Here we review the available evidence for each of these molecules

Chemical reception in vertebrate olfaction: evidence for multiple transduction pathways

Odorant detection takes place at the receptor neurons of the olfactory epithelium and odorant discrimination relies in an important degree on these chemosensory cells. Here we review the evidence for the participation of multiple transduction pathways in the mechanisms of odor recognition in olfactory neurons

Effects of alpha-MSH and cholinergic agents on cGMP and IP3 levels in rat brain slices

On one hand, it has been demonstrated that the exposure of rat brain slices containing caudate putamen and accumbens nuclei to alpha-MSH brings about an increase in cAMP. This increase is affected when dopamine is present in the incubation medium. On the other hand, an interaction of melanotropinergic-like peptides with acetylcholinergic drugs has been showed to be similar to the one observed with dopamine. In this study we have intended to measure cGMP Or IP3 in response to alpha-MSH, and also to study the interaction with cholinergic drugs by measuring the second messengers recently mentioned. cGMP and IP3 have been measured in tissues and medium in their response to the effect of alpha-MSH alone or in the presence of the peptide plus pilocarpine (selective muscarinic agonist) or atropine (selective muscarinic antagonist). None of them modified the cGMP levels when compared with lhe control group. The exposure of rat brain slices containing CP and Acc nuclei to alpha-MSH resulted in an increase in IP3 levels. Pilocarpine by itself brought about an increase of IP3 only when the highest doses was used. Atropine did not modify the IP3 content. However, when slices were exposured to both alpha-MSH and pilocarpine, IP3 content was similar to control values. The blockage of the muscarinic receptor with atropine blocked the IP3 increase induced by alpha-MSH as well. Therefore, we assume that alpha-MSH does not induce changes in cGMP but it does change the IP3 levels, probably acting at the muscarinic receptor level.

Efecto del Inositol 1, 4, 5 Trifosfato sobre [Ca2+] en músculos esqueléticos de sujectos susceptibles al síndrome de hipertemia maligna / Effects of Inositol 1, 4, 5 Triphosphate on free myoplasmic calcium concentration in malignante hyperthemia suceptible patients

Se estudió el efecto del inositol 1, 4, 5 trifosfato (InsP3) sobre la concentración de Ca++ libre de mioplásmico ([Ca++]) en biopsias musculares de sujetos sanos y susceptibles a hipertermia maligna (HM) con o sin encubación previa en dantrolene. El material utilizado incluyó microeléctrodos específicos para Ca++, y la microinyección de InsP3 por separado. En fibras musculares no susceptibles a HM, la inyección de 0,5 µM de InsP3 indujo un aumento de la [Ca++], de 0,12 ñ 0.01 µM a 0,37 ñ 0,03 µM que lle gó a 0,81 ñ 0,04 µM al doblar la dosis, con oscilación sarcométrica en casi la mitad de las preparaciones con esta dossis. El mismo procedimiento en miofibrillas susceptibles a HM produjo efectos mayores y más sostenidos; con 0,5 µM de InsP3 [Ca++], basal de 0,32 ñ 0,02 µM se elevó a 1,22 ñ 0,08 µM, y duplicando las dosis sólo se pudo medir algunas células que no sufrieron contracción local, que de 0,36 ñ 0,02 µM incrementaron la [Ca++], a 1,48 ñ 0,1 µM. La incubación previa con dantralone bloqueó el efecto del InsP3 sobre [Ca++], en ambos tipos de miofibrillas