Abstract
A significant number of chronic diseases are linked to perinatal nutrition, and prevention may be associated to naturally occurring components of breast milk. One key hormone in breast milk is leptin, related with the protection from obesity in the adulthood, thus knowing its changes through the day or lactation is crucial. We aimed to investigate the daily rhythms in the milk levels of leptin, together with other two related hormones, ghrelin and adiponectin, during lactation (days 5, 10 and 15) in rat dams, and the relation with morphometric parameters (dams and pups). Summarizing the main results, the existence of biological rhythms, but not daily and maybe circasemidian, was confirmed for the three hormones at the earliest period of lactation. The correlations performed generally showed a possible dependence of milk hormone levels on plasma levels at the early phase of lactation, while with the progression of lactation this dependence may fade and the hormone levels are suggested to be more dependent on mammary gland production/maturation. There was also a correlation between milk leptin and adiponectin levels, especially in the first half of lactation, suggesting a possible parallel regulation. Interestingly, we describe a milk leptin surge around the mid of lactation (at day 10) which may be related with pup´s growth (males and females) and with the well-known (in the literature) plasma leptin surge in pups. All this knowledge may be crucial for future applications in the development of formula milk and in relation with the role of leptin surge during lactation.
Highlights
The association between numerous chronic diseases, including obesity, with early nutrition has been established, and is related to the term metabolic “programming” [1,2,3], where the role of key components such as hormones during the early period of development may be key in pre-programing brain development and body functions, influencing the risk for diseases in the adulthood [4]
The results show that while ghrelin and plasma leptin in dams did not change when comparing the different days of lactation studied, there were significant changes for both milk and plasma adiponectin and for milk leptin
The first question formulated in this work was the possible existence of daily rhythms in the levels of leptin and other two important hormones present in mammalian milk and the answer is that we have found rhythms in the three hormones in milk, but not daily, since they have a period of about half a day, and only at the earliest phase of lactation (Figs 1–3)
Summary
The association between numerous chronic diseases, including obesity, with early nutrition (both during the prenatal and postnatal periods) has been established, and is related to the term metabolic “programming” [1,2,3], where the role of key components such as hormones during the early period of development may be key in pre-programing brain development and body functions, influencing the risk for diseases in the adulthood [4]. PLOS ONE | DOI:10.1371/journal.pone.0145376 December 17, 2015
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