title: Effects of delta-aminolevulinic acid and melatonin in the harderian gland of female Syrian hamsters.
abstract: Effects of delta-aminolevulinic acid (ALA) and melatonin were investigated in the female Syrian hamster Harderian gland. This is an organ physiologically exposed to strong oxidative stress due to the highest porphyrinogenic rates known in nature. Enzyme activities of porphyrin biosynthesis and of antioxidative protection, oxidative protein modification, and histological integrity were studied. In the porphyrin biosynthetic pathway, ALA and melatonin acted synergistically by downregulating ALA synthase (ALA-S) and stimulating product formation from ALA; the combination of ALA and melatonin suppressed ALA-S activity, down to about 1% of that in controls. While ALA effects on porphyrinogenesis can be interpreted in terms of homeostasis, melatonin's actions may be seen in relation to seasonality and/or reduction of oxidative stress. Among antioxidant enzymes, superoxide dismutase (SOD) and glutathione reductase (GR) activities were diminished by ALA, presumably due to the vulnerability of their active centers to free radicals, whereas melatonin moderately increased SOD. Both ALA and melatonin strongly stimulated catalase (CAT), thereby counteracting the oxidative stress induced by ALA and its metabolites. Nevertheless, exogenous ALA caused a strong net rise in protein carbonyl and considerable damage of tissue. When given together with ALA, melatonin antagonized these effects and largely protected the integrity of glandular structures.
authors.affiliation: Departamento de Morfología y Biología Celular, Universidad de Oviedo, Oviedo, Asturias, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Tomás-Zapico
authors.forename: Ana
authors.initials: A
authors.lastname: Coto-Montes
authors.forename: Jorge
authors.initials: J
authors.lastname: Martínez-Fraga
authors.forename: María Josefa
authors.initials: MJ
authors.lastname: Rodríguez-Colunga
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hardeland
authors.forename: Delio
authors.initials: D
authors.lastname: Tolivia
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002374:Catalase / Q000378:metabolism; D006224:Cricetinae; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology*; D005980:Glutathione Reductase / Q000378:metabolism; D006243:Harderian Gland / Q000187:drug effects* / Q000201:enzymology; D011163:Hydroxymethylbilane Synthase / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D008647:Mesocricetus; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D000623:Porphobilinogen Synthase / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D000622:Aminolevulinic Acid; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D011163:Hydroxymethylbilane Synthase; D000623:Porphobilinogen Synthase; D008550:Melatonin