Antioxidant Effect of Melatonin on the Functional Activity of Colostral Phagocytes in Diabetic Women

Melatonin is involved in a number of physiological and oxidative processes, including functional regulation in human milk. The present study investigated the mechanisms of action of melatonin and its effects on the functional activity of colostral phagocytes in diabetic women. Colostrum samples were collected from normoglycemic (N = 38) and diabetic (N = 38) women. We determined melatonin concentration, superoxide release, bactericidal activity and intracellular Ca2+ release by colostral phagocytes treated or not with 8-(Diethylamino) octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8) and incubated with melatonin and its precursor (N-acetyl-serotonin-NAS), antagonist (luzindole) and agonist (chloromelatonin-CMLT). Melatonin concentration was higher in colostrum samples from hyperglycemic than normoglycemic mothers. Melatonin stimulated superoxide release by colostral phagocytes from normoglycemic but not hyperglycemic women. NAS increased superoxide, irrespective of glycemic status, whereas CMTL increased superoxide only in cells from the normoglycemic group. Phagocytic activity in colostrum increased significantly in the presence of melatonin, NAS and CMLT, irrespective of glycemic status. The bactericidal activity of colostral phagocytes against enterophatogenic Escherichia coli (EPEC) increased in the presence of melatonin or NAS in the normoglycemic group, but not in the hyperglycemic group. Luzindole blocked melatonin action on colostrum phagocytes. Phagocytes from the normoglycemic group treated with melatonin exhibited an increase in intracellular Ca2+ release. Phagocytes treated with TMB-8 (intracellular Ca2+ inhibitor) decreased superoxide, bactericidal activity and intracellular Ca2+ release in both groups. The results obtained suggest an interactive effect of glucose metabolism and melatonin on colostral phagocytes. In colostral phagocytes from normoglycemic mothers, melatonin likely increases the ability of colostrum to protect against EPEC and other infections. In diabetic mothers, because maternal hyperglycemia modifies the functional activity of colostrum phagocytes, melatonin effects are likely limited to anti-inflammatory processes, with low superoxide release and bactericidal activity. © 2013 Morceli et al

Bactericidal index (mean ± SD, N = 7 in each treatment).

<p>Bactericidal activity by colostral phagocytes was determined with the acridine orange method. Phagocytes were pre-treated or not with 8-(Diethylamino) octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8) and incubated with enterophatogenic <i>Escherichia coli</i> (EPEC) in the presence of melatonin (MLT), N-acetyl-serotonin (NAS), luzindole or chloromelatonin (CMLT). * indicates difference from the 199 medium (ANOVA, P<0.05); + indicates intergroup differences within each treatment (ANOVA, P<0.05); ^# indicates differences between TMB-8 use within each treatment and group.</p

Superoxide release by colostrum phagocytes (mean ± SD, N = 8 per treatment).

<p>Phagocytes were incubated with enterophatogenic <i>Escherichia coli</i> (EPEC) in the presence of melatonin (MLT), N-acetyl-serotonin (NAS), luzindole or chloromelatonin (CMLT) and pre-treated or not with 8-(Diethylamino) octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8). In controls assays, phagocytes were pre-incubated with phosphate buffer solution (PBS).</p>*<p>indicates difference from the control treatment (ANOVA, P<0.05);</p>+<p>indicates intergroup differences within each treatment (ANOVA, P<0.05);</p>#<p>indicates differences between TMB-8 use within each treatment and group.</p

Mean (±SD; N = 10) melatonin levels (pg/mL) in the supernatant of colostrum from diabetic mothers *indicates difference between normoglycemic and hyperglycemic groups.

<p>Mean (±SD; N = 10) melatonin levels (pg/mL) in the supernatant of colostrum from diabetic mothers *indicates difference between normoglycemic and hyperglycemic groups.</p