title: The possible role of human milk nucleotides as sleep inducers.
abstract: Breast-milk contains a potent mixture of diverse components, such as the non-protein nitrogen fraction which includes nucleotides, whose variation in levels is evident throughout lactation. In addition, these substances play an important role in sleep homeostasis. In the present study, human milk samples were analyzed using a capillary electrophoresis system. The rhythmicity of each nucleotide was studied by cosinor analysis. It was found that the nucleotides 5'AMP, 5'GMP, 5'CMP, and 5'IMP have significant (P < 0.05) circadian rhythms, the acrophases of the first two being during the night, and of the latter two during the day. While 5'UMP did not show a clear circadian rhythm, there was an increase in its levels at night. In conclusion, the rise in nocturnal levels of 5'AMP, 5'GMP, and 5'UMP could be involved in inducing the 'hypnotic' action of breast-milk at night in the infant.
authors.affiliation: Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain. crissanchez@unex.es
authors.forename: Cristina L
authors.initials: CL
authors.lastname: Sánchez
authors.forename: Javier
authors.initials: J
authors.lastname: Cubero
authors.forename: Javier
authors.initials: J
authors.lastname: Sánchez
authors.forename: Belén
authors.initials: B
authors.lastname: Chanclón
authors.forename: Montserrat
authors.initials: M
authors.lastname: Rivero
authors.forename: Ana B
authors.initials: AB
authors.lastname: Rodríguez
authors.forename: Carmen
authors.initials: C
authors.lastname: Barriga
mesh_terms: D000249:Adenosine Monophosphate / Q000032:analysis; D000328:Adult; D001942:Breast Feeding; D002940:Circadian Rhythm; D003568:Cytidine Monophosphate / Q000032:analysis; D019075:Electrophoresis, Capillary; D005260:Female; D006157:Guanosine Monophosphate / Q000032:analysis; D006801:Humans; D007291:Inosine Monophosphate / Q000032:analysis; D008895:Milk, Human / Q000737:chemistry*; D009755:Night Blindness; D009711:Nucleotides / Q000032:analysis* / Q000502:physiology; D012890:Sleep / Q000502:physiology*
chemical_list: D009711:Nucleotides; D007291:Inosine Monophosphate; D000249:Adenosine Monophosphate; D006157:Guanosine Monophosphate; D003568:Cytidine Monophosphate