Effect of an injectable cabergoline formulation on serum prolactin (PRL) and milk secretion in early postpartum Beagle bitches

Methionine promotes crop milk protein synthesis through the JAK2-STAT5 signaling during lactation of domestic pigeons (Columba livia)

Crop milk is the sole source of nutrition that sustains young pigeons (squabs) throughout growth and development. Protein accounts for approximately 55% of the nutrients in crop milk; however, its regulation mechanism remains unclear. In our study, three experiments were conducted to investigate the possible underlying mechanism of crop milk protein synthesis and nutritional interventions. Isobaric tagging for relative and absolute quantification (iTRAQ) analysis found that the Janus activated kinase (JAK)/signal transducers and activators of transcription (STAT) pathway was significantly up-regulated in breeding pigeons during lactation compared to non-breeding pigeons. Moreover, the serum prolactin (PRL) levels increased, and the protein expression of the PRL receptor (PRLR)/JAK2/STAT5 pathway was significantly up-regulated during lactation. The serum PRL, the PRLR/JAK2/STAT5 pathway, the crop milk protein synthesis, and the squab growth performance were inhibited by bromocriptine mesylate injection, a PRL-specific inhibitor. In addition, dietary supplementation with 0.30% dl-methionine or dl-methionine-dl-methionine (especially 0.30% dl-methionine-dl-methionine), significantly increased serum PRL levels and PRLR/JAK2/STAT5 activity, and improved the crop milk protein synthesis. In conclusion, our results demonstrated that the PRL-induced PRLR/JAK2/STAT5 signaling pathway plays a vital regulatory role in crop milk protein synthesis, and 0.30% dl-methionine-dl-methionine is superior to dl-methionine in promoting crop milk protein synthesis.

Lactation and neonatal nutrition: defining and refining the critical questions

This paper resulted from a conference entitled "Lactation and Milk: Defining and refining the critical questions" held at the University of Colorado School of Medicine from January 18-20, 2012. The mission of the conference was to identify unresolved questions and set future goals for research into human milk composition, mammary development and lactation. We first outline the unanswered questions regarding the composition of human milk (Section I) and the mechanisms by which milk components affect neonatal development, growth and health and recommend models for future research. Emerging questions about how milk components affect cognitive development and behavioral phenotype of the offspring are presented in Section II. In Section III we outline the important unanswered questions about regulation of mammary gland development, the heritability of defects, the effects of maternal nutrition, disease, metabolic status, and therapeutic drugs upon the subsequent lactation. Questions surrounding breastfeeding practice are also highlighted. In Section IV we describe the specific nutritional challenges faced by three different populations, namely preterm infants, infants born to obese mothers who may or may not have gestational diabetes, and infants born to undernourished mothers. The recognition that multidisciplinary training is critical to advancing the field led us to formulate specific training recommendations in Section V. Our recommendations for research emphasis are summarized in Section VI. In sum, we present a roadmap for multidisciplinary research into all aspects of human lactation, milk and its role in infant nutrition for the next decade and beyond.