ABSTRACT
It has been suggested that spinach methanolic extract (SME) inhibits the formation of advanced glycation end products (AGEs), which are increased during diabetes progression, so it is important to know if SME has beneficial effects in the diabetic retina. In this study, in vitro assays showed that SME inhibits glycation, carbonyl groups formation, and reduced-thiol groups depletion in bovine serum albumin incubated either reducing sugars or methylglyoxal. The SME effect in retinas of streptozotocin-induced diabetic rats (STZ) was also studied (n = 10) in the normoglycemic group, STZ, STZ rats treated with SME, and STZ rats treated with aminoguanidine (anti-AGEs reference group) during 12 weeks. The retina was sectioned and immunostained for Nε-carboxymethyl lysine (CML), receptor RAGE, NADPH-Nox4, inducible nitric oxide synthase (iNOS), 3-nitrotyrosine (NT), nuclear NF-κB, vascular endothelial growth factor (VEGF), glial fibrillary acidic protein (GFAP), S100B protein, and TUNEL assay. Lipid peroxidation was determined in the whole retina by malondialdehyde (MDA) levels. The results showed that in the diabetic retina, SME reduced the CML-RAGE co-localization, oxidative stress (NOX4, iNOS, NT, MDA), inflammation (NF-κB, VEGF, S100B, GFAP), and apoptosis (p < 0.05). Therefore, SME could attenuate the retinal degeneration by inhibition of CML-RAGE interaction.
ABSTRACT
Slo3 is a pH-sensitive and weakly voltage-sensitive potassium channel that is essential for male fertility in mouse and whose expression is regarded as sperm-specific. These properties have proposed Slo3 as a candidate target for male contraceptive drugs. Nonetheless, the tissue distribution of Slo3 expression has not been rigorously studied yet. Applying computational and RT-PCR approaches, we identified expression of two short Slo3 isoforms in somatic mouse tissues such as brain, kidney and eye. These isoforms, which seem to result of transcription starting sites between exons 20 and 21, have an identical open reading frame, both encoding the terminal 381 amino acids of the cytosolic Slo3 domain. We corroborated the expression of these isoforms in mouse brain and testis by Western-blot. The complete isoform encoding the Slo3 ion channel was uniquely detected in testis, both at transcript and protein level. Although the functional role of the cytosolic Slo3 isoforms remains to be established, we propose that they may have a functional effect by modulating Slo channels trafficking and/or activity. This study confirms that expression of full-length Slo3 is sperm-specific but warns against developing contraceptive drugs targeting the C-terminal tail of Slo3 channels.