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Ghrelin Secretion in Preterm Neonates Progressively Increases and Is Refractory to the Inhibitory Effect of Food Intake

Division of Pediatrics (S.B., R.B., A.R., D.V., A.P., S.S., M.Z., G.B.), Department of Medical Sciences, University of Piemonte Orientale, 28100 Novara, Italy; Division of Endocrinology (F.B., E.G.), Department of Internal Medicine, University of Turin, 10126 Turin, Italy; and Department of Pediatrics (G.R.), Regional Hospital, Bolzano 39100, Italy

Address all correspondence and requests for reprints to: Gianni Bona, M.D., Division of Pediatrics, Department of Medical Sciences, University of Piemonte Orientale "Amedeo Avogadro," Corso Mazzini 18, 28100 Novara, Italy. E-mail: gianni.bona{at}maggioreosp.novara.it.

Context: Ghrelin, a natural GH secretagogue, is mainly characterized by nonendocrine activities such as orexigenic effect and modulation of the endocrine and metabolic response to variations in energy balance. Ghrelin levels have been reported to be negatively associated with insulin secretion, enhanced in anorexia, and reduced in obesity. Ghrelin levels in newborns were shown to be similar to those found in children and adults without any gender-related difference.

Objective: The aim of this study was to evaluate ghrelin variations in preterm newborns as a function of fasting and feeding.

Methods: To this end, in 31 preterm neonates (13 males and 18 females) categorized as appropriate for gestational age, total ghrelin levels were measured in cord blood and then on the fourth day of life before and after meals.

Results: Ghrelin levels in cord blood [(median 25th–75th centile) 184; 122–275 pg/ml] were higher (P < 0.006) than levels measured in the mothers at delivery (167.0; 89–190 pg/ml). In newborns on the fourth day of life, ghrelin levels in fasting conditions (451; 348–649 pg/ml) were higher (P < 0.0004) than those in cord blood. The meal did not at all modify ghrelin levels (476; 302–775 pg/ml), which were unchanged, compared with those in fasting condition. Total ghrelin levels in cord blood were not associated with weight and length; conversely, on the fourth day of life ghrelin levels in newborns were negatively correlated to birth weight as well as the present weight (P = 0.05, r = –0.4). Ghrelin levels were independent of gender, type of delivery, and the kind of feeding regimen.

Conclusions: The secretion of total ghrelin increases from delivery to the fourth day of life when it is refractory to the inhibitory effect of food intake, but it is negatively correlated to body weight.