Adenosine triphosphate (ATP) has been proposed to play a role as a neurotransmitter in the retina, but not much attention has been given to the regulation of ATP release from retinal neurons. In this work, we investigated the release of ATP from cultures enriched in amacrine-like neurons. Depolarization of the cells with KCl, or activation of ␣-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) receptors, evoked the release of ATP, as determined by the luciferin/luciferase luminescent method. The ATP release was found to be largely Ca 2؉ dependent and sensitive to the botulinum neurotoxin A, which indicates that the ATP released by cultured retinal neurons originated from an exocytotic pool. Nitrendipine and -Agatoxin IVA, but not by -Conotoxin GVIA, partially blocked the release of ATP, indicating that in these cells, the Ca 2؉ influx necessary to trigger the release of ATP occurs in part through the L-and the P/Q types of voltage-sensitive Ca 2؉ channels (VSCC), but not through N-type VSCC. The release of ATP increased in the presence of adenosine deaminase, or in the presence of 1,3-dipropyl-8cyclopentylxanthine (DPCPX), an adenosine A 1 receptor antagonist, showing that the release is tonically inhibited by the adenosine A 1 receptors. To our knowledge, this is the first report showing the release of endogenous ATP from a retinal preparation.

BackgroundTriple negative breast cancers (TNBC) are associated with an aggressive clinical course, earlier recurrence and short survival. BRCA – mutated tumours represent up to 25% of all TNBC. BRCA status is being studied as a predictive biomarker of response to platinum agents. However, the predictive role of BRCA status is still uncertain in this setting. Since TNBC is a very heterogeneous group of diseases, it is important to identify subsets of TNBC patients that may benefit from platinum-based therapy. This study aims to establish if the presence of a germline BRCA mutation in women with TNBC improves the pathologic complete response (pCR) after neoadjuvant chemotherapy with platinum compounds.MethodsAn extensive literature search was performed in MEDLINE, EMBASE and LILACS databases, WHO (WHO International Clinical Trials Registry Platform) and the Cochrane Controlled Trials Register Database, for online trial registries and conference proceedings. The measurement of pCR was assessed by pathology review of breast specimen and lymph nodes.ResultsThe overall OR was computed using random effects models.Seven studies were included, comprising a total of 808 TNBC patients, among which 159 were BRCA mutated. Among mutated TNBC patients, 93 (93/159; 58.4%) achieved pCR, while 410 wildtype patients (410/808; 50.7%) showed pCR (OR 1.459 CI 95% [0.953–2.34] p = 0.082) although this result did not reach statistical significance.ConclusionsThis meta-analysis shows that the addition of platinum to chemotherapy regimens in the neoadjuvant setting increases pCR rate in BRCA – mutated as compared to wild-type TNBC patients. However, this trend did not achieve statistical significance.Trial registration CRD42018092341

This review was registered at PROSPERO (CRD42015013494).

Retinal amacrine cells express metabotropic glutamate receptors (mGluRs), but their physiological role is unknown. We investigated the effect of mGluR on [(3)H]acetylcholine release ([(3)H]ACh) from cultured chick amacrine-like neurons. Activation of group III mGluR with the agonist L(+)-2-amino-4-phosphonobutyric acid (L-AP4) inhibited [(3)H]ACh release evoked by 25 mM KCl in a dose-dependent manner, and this effect was sensitive to pertussis toxin. In contrast, activation of group I or II mGluR with (S)-3, 5-dihydroxyphenylglycine (DHPG) and (2S,2'R,3'R)-2-(2', 3'-dicarboxycyclopropyl)glycine (DCG-IV), respectively, did not affect significantly [(3)H]ACh release. The effect of L-AP4 on [(3)H]ACh release was sensitive to nitrendipine, suggesting that it is, at least in part, due to inhibition of L-type Ca(2+) channels. Activation of group III mGluR also partly inhibited omega-conotoxin GVIA-sensitive Ca(2+) channels, coupled to [(3)H]ACh release. The L-AP4 did not affect the cAMP levels measured in amacrine-like neurons depolarized with 25 mM KCl or stimulated with forskolin, indicating that the effect of group III mGluR on [(3)H]ACh release is not due to inhibition of adenylyl cyclase activity. Inhibition of protein kinase A with KT-5720 was without effect on [(3)H]ACh release evoked by 25 mM KCl, further indicating that the effect of group III mGluR on [(3)H]ACh release cannot be attributed to the inhibition of the kinase. The effect of L-AP4 on [(3)H]ACh release was reversed by DHPG or by DCG-IV, and activation of group II mGluR also partially inhibited cAMP production stimulated by forskolin. Taken together, our results show that the effect of group III mGluR on [(3)H]ACh release may be due to a direct inhibition of L- and N-type Ca(2+) channels and is modulated by group I and group II mGluR.

We investigated the effect of adenosine A1 receptors on the release of acetylcholine (ACh) and GABA, and on the intracellular calcium concentration ([Ca2+]i) response in cultured chick amacrine-like neurons, stimulated by KCl depolarization. The KCl-induced release of [3H]ACh, but not the release of [14C]GABA, was potentiated when adenosine A1 receptor activation was prevented by perfusing the cells with adenosine deaminase (ADA) or with 1,3-dipropyl-8-cycloentylxanthine (DPCPX). The changes in the [Ca2+]i induced by KCl depolarization, measured in neurite segments of single cultured cells, were also modulated by endogenous adenosine, acting on adenosine A1 receptors. Our results show that adenosine A1 receptors inhibit Ca2+ entry coupled to ACh release, but not to the release of GABA, suggesting that the synaptic vesicles containing each neurotransmitter are located in different zones of the neurites, containing different VSCC and/or different densities of adenosine A1 receptors.