Milk-borne prolactin and neonatal development

Abstract

Milk is primarily regarded as a food furnishing essential nutrients for infant growth and development, but milk can also serve as a vehicle for mother to neonate transfer of molecules that regulate development. A wide array of biologically active compounds such as hormones, cytokines and enzymes are present in milk, especially early milk. The premise that prolactin (PRL) in milk is an important and possibly essential developmental factor for the newborn is explored. Both PRL and structurally modified isoforms are abundant in early milk and gradually diminish with the progression of lactation. Milk PRL is absorbed and biologically active in the neonate. Assays of PRL variants, experimental paradigms to test them as developmental regulators and the body of evidence supporting the hypothesis that milk PRL regulates differentiation and maturation of neonatal neuroendocrine, reproductive, and immune systems is presented.

Reduced Thymic Size and Numbers of Splenic CD4+and CD8+Cells in Artificially Reared Mouse Pups

“…23) This prolactin and its structurally modified isoforms are abundant in early milk and gradually diminish with the progression of lactation. 8) However the size of the spleen in the AR-0 pups had not decreased at 10 days of age in our experiment. Prolactin may be produced in the spleen at 10 days of age in the AR-0 pups, because mRNA of prolactin was expressed in all spleen samples during 0-60 days postpartum.…”

“…It is also known that many immunologically active substances such as prolactin, immunoglobulins, transforming growth factor, lactoferrin, and cytokines are secreted in breast milk and are abundant in colostrum. [6][7][8] In relation to this, it has been reported that, during the lactation period, human milk has the ability to protect against numerous infections such as otitis media, upper and lower respiratory tract infections, diarrhea, urinary tract infections, neonatal septicemia, and necrotizing enterocolitis. [9][10][11] Thus, it is very important to investigate the effects of the type of early nutrition on newborn infants, particularly with regard to immune development.…”

Human milk cortisol is associated with infant temperament

“…Further, excesses or deficits in other milk proteins and hormones also appear to exert lasting effects on development (Ellis et al, 1996; Sullivan et al, 2003). Biochemical communication through milk represents one potentially important maternal signal that offspring may incorporate to maximize adaptation to their environments.…”

Intestinal absorption and renal reabsorption of calcium throughout postnatal development

“…Prolactin is a peptide hormone that is present in high amounts in early breast milk, but has a declining concentration through lactation. 66,67 It consists of several isoforms produced via alternative splicing, proteolytic cleavage, and post-translational modifications. 68 Maternal prolactin is absorbed and bioactive in neonatal rats where the prolactin receptor is present on epithelial cells throughout the small and large intestines as well as the duodenum and colon of humans.…”