Person: Crooke Álvarez, Almudena
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First Name
Almudena
Last Name
Crooke Álvarez
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Bioquímica y Biología Molecular
Area
Bioquímica y Biología Molecular
Identifiers
6 results
Search Results
Now showing 1 - 6 of 6
Item Melatonin Makes Me Feel Awake! Seven Years of Lab Experience (2000-2007)(Anales de la Real Academia Nacional de Farmacia, 2007) Pelaez, Teresa; Mediero Muñoz, Aránzazu; Alarma-Estrany, Pilar; Loma Lozano, Patricia; Guzmán Aránguez, Ana Isabel; Crooke Álvarez, Almudena; Colligris, Basilio; Peral Cerda, María Asunción; Pintor Just, Jesús JerónimoThe research on the effect of melatonin on intraocular pressure (IOP) is reviewed from the hystorical point of view of our laboratory. The original idea of melatonin modulating intraocular pressure has been improved by using selective compounds for MT2 and specially melatonin MT3 receptors. The selective compound 5-methoxyamino N-acetyltryptamine (5-MCA-NAT) has been an attractive compound due to its ability to reduce IOP about 40%, therefore being a good candidate to the treatment of the ocular hypertension linked to glaucoma. More compounds have been developed and tested permitting us to have a more accurate panorama of those receptors controlling the relevant process of intraocular pressure.Item Melatonin Receptors Trigger cAMP Production and Inhibit Chloride Movements in Nonpigmented Ciliary Epithelial Cells(Journal of Pharmacology and Experimental Therapeutics, 2015) Huete Toral, Fernando; Crooke Álvarez, Almudena; Martínez Águila, Alejandro; Pintor Just, Jesús JerónimoMelatonin and its analog 5-MCA-NAT (5-methylcarboxyamino-N-acetyl tryptamine) are active compounds reducing intraocular pressure (IOP). This action is mediated through MT2 and the putative MT3 melatonin receptor, producing a transient reduction of IOP that lasts for a few hours and has not yet been characterized. The use of melatonin and its analog are causing a decrease in chloride efflux from rabbit nonpigmented epithelial cells (NPE), possibly explaining the decrease in IOP. Melatonin and 5-MCA-NAT inhibited rabbit NPE chloride release in a concentration-dependent manner, whereas the pD2 values were between 4.5 ± 1.2 and 4.4 ± 1.0, respectively. Melatonin hypotensive action was enhanced by the presence of MT2 antagonists, such as DH97 (N-pentanoyl-2-benzyltryptamine) and 4-P-P-DOT (4-phenyl-2-propionamidotetralin) and by the nonselective melatonin receptor antagonist luzindole. Prazosin (1.5 µM) partially reverses the melatonin action by acting as a selective MT3 antagonist. However, at 15 nM it acts as an α-adrenergic receptor antagonist, enhancing the melatonin effect. Regarding the intracellular pathways triggered by melatonin receptors, neither phospholipase C/protein kinase C pathway nor the canonical reduction of intracellular cAMP was responsible for melatonin or 5-MCA-NAT actions. On the contrary, the application of these substances produced a concentration-dependent increase of cAMP, with pD2 values of 4.6 ± 0.2 and 4.9 ± 0.7 for melatonin and 5-MCA-NAT, respectively. In summary, melatonin reduces the release of chloride concomitantly to cAMP generation. The reduction of Cl− secretion accounts for a decrease in the water outflow and therefore a decrease in aqueous humor production. This could be one of the main mechanisms responsible for the reduction of IOP after application of melatonin and 5-MCA-NAT.Item The role and therapeutic potential of melatonin in age-related ocular diseases(Journal of Pineal Research, 2017) Crooke Álvarez, Almudena; Huete Toral, Fernando; Colligris, Basilio; Pintor Just, Jesús JerónimoThe eye is continuously exposed to solar UV radiation and pollutants, making it prone to oxidative attacks. In fact, oxidative damage is a major cause of age-related ocular diseases including cataract, glaucoma, age-related macular degeneration and diabetic retinopathy. Since the nature of lens cells, trabecular meshwork cells, retinal ganglion cells, retinal pigment epithelial cells and photoreceptors is post-mitotic, autophagy plays a critical role in their cellular homeostasis. In age-related ocular diseases, this process is impaired, thus, oxidative damage becomes irreversible. Other conditions such as low- grade chronic inflammation and angiogenesis also contribute to the development of retinal diseases (glaucoma, age-related macular degeneration and diabetic retinopathy). As melatonin is known to have remarkable qualities such as antioxidant/antinitridergic, mitochondrial protector, autophagy modulator, anti-inflammatory and anti-angiogenic, it can represent a powerful tool to counteract all these diseases. The present review analyzes the role and therapeutic potential of melatonin in age-related ocular diseases, focusing on nitro-oxidative stress, autophagy, inflammation and angiogenesis mechanisms.Item Contact Lenses Loaded with Melatonin Analogs: A Promising Therapeutic Tool against Dry Eye Disease(Journal of Clinical Medicine, 2022) Navarro Gil, Francisco Javier; Huete Toral, Fernando; Domínguez Godínez, Carmen Olalla; Carracedo Rodríguez, Juan Gonzalo; Crooke Álvarez, Almudena; Versura, Piera; Dogru, MuratMelatonin analogs topically administered evoke a potent tear secretagogue effect in rabbits. This route of drug administration requires high drug concentration and frequent dosing due to its reduced ocular surface retention. Therefore, contact lenses (CLs) have emerged as an alternative drug- delivery system that prolongs drug retention in the cornea, improving its therapeutic performance. This study explores the in vitro ability of five commercially available hydrogel CLs to act as a delivery system for melatonin analogs and the in vivo secretagogue effect of melatonin analog-loaded CLs. We soaked CLs with melatonin or melatonin analog solutions (1 mM) for 12 h. Spectroscopic assays showed that IIK7-loaded CLs led to the inadequate delivery of this compound. Conventional hydrogel lenses loaded with agomelatine released more agomelatine than silicone ones (16–33% more). In contrast, the CLs of silicone materials are more effective as a delivery system of 5-MCA-NAT than CLs of conventional materials (24–29%). The adaptation of CLs loaded with agomelatine or 5-MCA-NAT in rabbits triggered a higher tear secretion than the corresponding eye drops (78% and 59% more, respectively). These data suggest that CLs preloaded with melatonin analogs could be an adequate strategy to combat aqueous tear deficient dry eye disease.Item Effect of Melatonin and Analogues on Corneal Wound Healing: Involvement of Mt2 Melatonin Receptor(Current Eye Research, 2015) Crooke Álvarez, Almudena; Guzmán Aránguez, Ana Isabel; Mediero Muñoz, Aránzazu; Alarma Estrany, Pilar; Carracedo Rodríguez, Juan Gonzalo; Peláez García, María Teresa; Peral Cerda, María Asunción; Pintor Just, Jesús JerónimoPurpose: We have investigated the effect of melatonin and its analogues on rabbit corneal epithelial wound healing. Methods: New Zealand rabbits were anaesthetised and wounds were made by placing Whatman paper discs soaked in n-heptanol on the cornea. Melatonin and analogues (all 10 nmol) were instilled. Wound diameter was measured every 2 hours by means of fluorescein application with a Topcon SL-8Z slit lamp. Melatonin antagonists (all 10 nmol) were applied 2 hours before the application of the n-heptanol-soaked disc and then every 6 hours together with melatonin. To confirm the presence of MT2 receptors in corneal epithelial cells immunohistochemistry, Western blot and RT-PCR assays in native tissue and in rabbit corneal epithelial cells were performed. The tear components were extracted then processed by HPLC to quantify melatonin in tears. Results: Migration assays revealed that melatonin and particularly the treatment with the MT2 agonist IIK7, accelerated the rate of healing (p < 0.001). The application of the non-selective melatonin receptor antagonist luzindole and the MT2 antagonist DH97 (but not prazosin), prevented the effect of melatonin on wound healing (both p < 0.001). Immunohistochemistry, Western blot and RT-PCR assays showed the presence of MT2 melatonin receptor in corneal epithelial cells. In addition, we have identified melatonin in tears and determined its daily variations. Conclusions: These data suggest that MT2 receptors are implicated in the effect of melatonin on corneal wound healing regulating migration rate. This suggests the potential use of melatonin and its analogues to enhance epithelial wound healing in ocular surface disease.Item Involvement of carbonic anhydrases in the ocular hypotensive effect of melatonin analogue 5‐MCA‐NAT(Journal of Pineal Research, 2011) Martínez Águila, Alejandro; Crooke Álvarez, Almudena; Huete Toral, Fernando; Martín Gil, Alba; Pintor Just, Jesús JerónimoWe have previously demonstrated that melatonin and its analogue, 5-methoxycarbonylamino-N-acetyltryptamine (5-MCA-NAT), reduce intraocular pressure (IOP) in New Zealand rabbits. More recently, we have shown that 5-MCA-NAT can also regulate ciliary adrenoceptor gene expression. Like adrenoceptors, carbonic anhydrase (CA) enzymes are involved in aqueous humour secretion by the ocular ciliary epithelium. Moreover, CA enzymes have been reported to be regulated by melatonin. Hence, the aim of this study was to investigate whether the hypotensive effect of 5-MCA-NAT is also because of a regulation of CA genes and enzymes. Time course of 5-MCA-NAT effect on rabbit IOP was followed for 7 hr every day for up to 144 hr (6 days). 5-MCA-NAT reduced IOP, maximally by 51.30 ± 2.41% (at 3 hr), and the hypotensive effect was maintained for up to 96 hr with a single application. IOP studies with 5-MCA-NAT plus Trusopt® and immunohistochemical analysis confirmed that CA are molecular targets of 5-MCA-NAT. In addition, real-time quantitative PCR (qPCR) and immunocytochemical assays were performed to determine changes in CA2 (CAII) and CA12 (CAXII) expression in cultured rabbit nonpigmented ciliary epithelial cells (NPE) treated with 5-MCA-NAT. NPE cells showed a prominent decrease in both CA, at the mRNA and protein levels. These data confirm that the long-term hypotensive effect of 5-MCA-NAT is also due, to a down-regulation of CA2 (CAII) and CA12 (CAXII) expression.