Serotoninergic and Circadian Systems: Driving Mammary Gland Development and Function

Abstract

Since lactation is one of the most metabolically demanding states in adult female mammals, beautifully complex regulatory mechanisms are in place to time lactation to begin after birth and cease when the neonate is weaned. Lactation is regulated by numerous different homeorhetic factors, all of them tightly coordinated with the demands of milk production. Emerging evidence support that among these factors are the serotonergic and circadian clock systems. Here we review the serotoninergic and circadian clock systems and their roles in the regulation of mammary gland development and lactation physiology. We conclude by presenting our hypothesis that these two systems interact to accommodate the metabolic demands of lactation and thus adaptive changes in these systems occur to maintain mammary and systemic homeostasis through the reproductive cycles of female mammals.

Effect of genetic and nongenetic factors on chemical composition of individual milk samples from dromedary camels (Camelus dromedarius) under intensive management

“…However, the amplitude of annual changes in fat and protein levels in our study was greater than what had been observed in bovine milk at much higher latitude. Taking into account all the aforementioned information, we hypothesized that seasonal changes in the chemical composition of camel milk may reflect an endogenous circannual biological rhythm with a strong underlying pacemaker that is generated by the circadian system and entrained by environmental cues (Casey and Plaut, 2012;Suárez-Trujillo and Casey, 2016). To support this hypothesis, El Allali et al (2013) recently demonstrated the existence of an endogenous circadian clock in dromedaries by describing rhythmic daily changes in body temperature under a constant photoperiod and ambient temperature.…”

“…To support this hypothesis, El Allali et al (2013) recently demonstrated the existence of an endogenous circadian clock in dromedaries by describing rhythmic daily changes in body temperature under a constant photoperiod and ambient temperature. In addition, an increasing body of evidence suggests that central and peripheral (mammary gland) circadian clocks regulate both the daily and seasonal changes in expression of genes in the mammary gland that are responsible for controlling milk synthesis (Casey and Plaut, 2012;Suárez-Trujillo and Casey, 2016). The positive effect of photoperiod on milk yield has already been demonstrated in several dairy animal species (Dahl et al, 2012), but in vivo data associating circannual changes in milk composition with endogenous rhythms or photoperiod are scarce.…”

Non-conventional features of peripheral serotonin signalling — the gut and beyond

“…Other likely actions not covered here include mammary gland development 65 , allergic airway inflammation 66 , and intercellular signaling in taste buds 67 . The appreciation of these contributions of 5-HT to an assortment of body functions offers opportunities to gain a better understanding of the mechanisms involved in their regulations, and it also draws attention to systems that could be inadvertently affected by therapies that target elements of 5-HT signaling.…”

Birth practices: Maternal‐neonate separation as a source of toxic stress

“…The neuronal changes to sensitize the maternal brain to mothering involve several complex systems. We have earlier discussed the oxytocinergic and the dopaminergic systems, but there are also endorphin systems, prolactin and mammary physiology, serotonin systems (Suarez-Trujillo & Casey, 2016), and epinephrine and stress-related systems (Buckley, 2015). Animal parenting has been extensively studied (Kinsley & Lambert, 2008), allowing also a life history interpretation of what is involved for the human mother and family.…”