A study conducted by the NYU Grossman School of Medicine has revealed that an infant’s cries can trigger the release of the hormone oxytocin in mothers, thereby aiding in the production of breast milk. This research highlights the pivotal role played by hormonal discharge in the realms of breastfeeding and ongoing maternal caregiving, even in states of fatigue.
This work was spearheaded by scientists from the NYU Grossman School of Medicine and delves into an anciently observed phenomenon across humans and other mammals. This phenomenon stipulates that when an infant initiates a feeding session, its cries, rather than the act of suckling itself, induce the largest surges of oxytocin. Despite long-standing studies confirming this, the exact mechanisms and purpose of this cry-induced milk release have remained elusive until now.
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Underlying Mechanisms for Oxytocin Release
According to the study, set to be published on September 20 in the scientific journal Nature, the cries of a mouse pup are processed in a specific region of the mother’s brain known as the posterior intralaminar nucleus of the thalamus (PIL). This area subsequently signals oxytocin-secreting neurons in another part of the brain, the hypothalamus, which serves as a central regulator for hormonal activities.
These hypothalamus neurons are typically restrained by proteins serving as gatekeepers, thereby avoiding unwarranted releases and wasted milk. However, after a consistent period of crying lasting 30 seconds, signals from the PIL accumulate enough to override these inhibitory proteins and trigger the release of oxytocin.
Habon Issa, a co-lead author of the study and a graduate student at NYU Langone Health, stated, “This research elucidates how a crying infant prepares its mother’s brain to precondition her body for lactation. Absence of such priming can result in a several-minute delay between suckling and milk flow, potentially causing a distressed infant and a stressed parent.”
Specificity of Oxytocin Release and Mother-Infant Bond
Moreover, the study disclosed that only mothers, and not nulliparous females, experience this oxytocin spike. Furthermore, the mother’s brain circuitry responded solely to her offspring’s cries, not to artificially created sounds mimicking natural cries.
Issa points out that the study employs a relatively novel type of molecular sensor, called iTango, to directly measure oxytocin release from brain cells in real time. Previously, researchers relied on indirect methods due to the rapid degradation of the hormone.
Impact on Maternal Behavior
The research team also investigated how this neural circuit influences maternal behaviors. Normally, mouse mothers are quick to retrieve their young if they wander or are separated from the nest. However, when the connection between the PIL and oxytocin neurons was chemically interrupted, the mothers displayed fatigue and ceased retrieving their young. Reactivation of the system restored their diligent care.
Robert Froemke, PhD, the study’s senior author, asserts that these findings suggest that this cry-induced neural pathway is critical not only for lactation but also for sustaining maternal attention and providing effective care to offspring, even in situations of maternal fatigue.
It should be noted that the researchers did not directly measure lactation but focused on the hormonal activities prompting it. Understanding these mechanisms could potentially offer new avenues to assist human mothers facing difficulties in breastfeeding.
Froemke holds positions in both the Department of Neuroscience and Physiology and the Department of Otolaryngology – Head and Neck Surgery at NYU Langone. The research was funded through grants from the National Institutes of Health and additional organizations, and involved several other contributors from NYU Langone and external institutions.
Reference: Published on September 20, 2023, in Nature, under the title “Neural circuitry for maternal oxytocin release induced by infant cries.” DOI: 10.1038/s41586-023-06540-4
The study received funding from National Institutes of Health grants T32MH019524, P01NS107616, and DP1MH119428, as well as support from the Natural Sciences and Engineering Research Council of Canada PGS-D Fellowship and a Howard Hughes Medical Institute Faculty Scholarship. Besides Issa and Froemke, other investigators included former NYU investigator Silvana Valtcheva, PhD, now at the University of Cologne in Germany, and several other researchers from NYU Langone and Johns Hopkins University.
Frequently Asked Questions (FAQs) about Oxytocin Release in Mothers Triggered by Infant Cries
What is the main focus of the study conducted by NYU Grossman School of Medicine?
The main focus of the study is to understand the neurological and hormonal mechanisms that lead to the release of oxytocin in mothers in response to their infants’ cries. This oxytocin release aids in breast milk production and has implications for maternal care.
What is the significance of oxytocin release in this context?
Oxytocin release plays a crucial role in facilitating breast milk production and is essential for nursing and ongoing maternal care. The release of this hormone also helps to maintain maternal focus and care for the infant, even when the mother is fatigued.
How was the study conducted?
The study was conducted using female mice as subjects. Using a type of molecular sensor known as iTango, researchers measured actual oxytocin release from brain cells in real time. They also examined the flow of sound information through different areas of the brain to understand how cries trigger milk flow.
Which part of the mother’s brain is involved in processing the infant’s cries?
The infant’s cries are processed in a specific area of the mother’s brain known as the posterior intralaminar nucleus of the thalamus (PIL). This region then signals oxytocin-secreting neurons in another part of the brain, the hypothalamus, to release oxytocin.
What happens after 30 seconds of continuous crying by the infant?
After 30 seconds of continuous crying, signals from the PIL accumulate enough to override inhibitory proteins in the hypothalamus neurons that normally act as gatekeepers. This leads to the release of oxytocin, aiding in breast milk production.
What is the specificity of the oxytocin release?
The study disclosed that only mothers, and not nulliparous females (females who have never given birth), experience the oxytocin spike. Moreover, the mother’s brain circuitry responded solely to her own offspring’s cries and not to artificially created sounds.
How does this neural circuitry affect the mother’s behavior towards her infant?
When the connection between the PIL and oxytocin neurons is intact, mothers quickly retrieve their young if they wander away or are separated from the nest. However, when this connection is chemically disrupted, mothers display signs of fatigue and cease retrieving their young until the system is reactivated.
What are the potential implications of this study for human mothers?
Understanding these mechanisms may offer new approaches to assist human mothers who want to breastfeed but encounter difficulties. However, it should be noted that the study was conducted on mice, and further research is needed to confirm its applicability to humans.
Who funded the research?
The research received funding from National Institutes of Health grants, as well as additional support from the Natural Sciences and Engineering Research Council of Canada PGS-D Fellowship and a Howard Hughes Medical Institute Faculty Scholarship.
Who were the key researchers involved in the study?
The study was led by Habon Issa, a graduate student at NYU Langone Health, and Robert Froemke, PhD, the senior author. It also involved several other researchers from NYU Langone and external institutions, including Johns Hopkins University.
More about Oxytocin Release in Mothers Triggered by Infant Cries
- NYU Grossman School of Medicine
- Nature Journal
- National Institutes of Health (NIH)
- Natural Sciences and Engineering Research Council of Canada
- Howard Hughes Medical Institute
- Department of Neuroscience and Physiology at NYU Langone
- Oxytocin and Maternal Behavior
- Johns Hopkins University Neuroscience
7 comments
Interesting read. but why only mice? Cant wait to see how this translates to humans. Its about time we had more studies focussed on moms and babies.
The tech they used is pretty amazing. Measuring oxytocin release in real time? thats next level stuff right there.
Wow, this is really fascinating stuff! Never knew how deep the connection between a mom and her newborn can go. It’s like, there’s a whole science behind it or something.
Honestly, i wish I had known all this when i was having trouble breastfeeding. Could’ve been a big help. Nature’s really amazing, huh?
The part where it says mothers will retrieve their young no matter how many times they stray, thats love right there. Exhausted or not, moms are just amazing!
Who would’ve thought cries could be so powerful, always thought it was the suckling part that did the magic. But hey, guess we learn something new everyday.
So this is why moms are so in tune with their babies! Science backing up what we kinda knew already, but still cool to see the facts laid out.