Introducing the brain: preparing the brain for birth (Introduction)

by David Turell , Friday, October 06, 2023, 15:59 (204 days ago) @ David Turell

Mouse brain studies:

https://mail.google.com/mail/u/0/#inbox/FMfcgzGtxdQCZPrjlTZTLFcJlHBjRvCL

"Pregnant mammals, from mice to humans, experience surges of hormones that prepare their bodies for the task of gestation. These hormones also reprogram the brain to induce parental behaviors, and now—thanks to clever genetic engineering—researchers have uncovered how this reprogramming happens in the brains of female mice.

"During pregnancy, the levels of steroid hormones like estradiol and progesterone rise. In addition to signaling changes in organs like the uterus and mammary glands, these hormones influence the brain to induce “mothering” behaviors such as nest building and an increased propensity for nurturing babies. To figure out how this happens, researchers developed mice where the hormones’ receptors could be selectively destroyed in specific neurons. This revealed that the two hormones have different effects: Estradiol tweaks which neurons respond to the sounds of pups temporarily, while progesterone leads to the formation of new synapses that promote mothering behaviors long-term.

"Intriguingly, blocking just these two hormones from signaling to certain neurons in a part of the brain was enough to get rid of a mouse’s maternal behavior entirely. “This was unexpected given the broad hormonal milieu of pregnancy,” Margaret McCarthy says in a related Perspective, and warrants further investigation."

From the paper itself:

"This was unexpected given the broad hormonal milieu of pregnancy, which includes increased oxytocin and prolactin, and because many other neuronal types express both steroid receptors. It may be that some component of pregnancy creates this specificity— a hypothesis that can be tested by inducing maternal behavior in virgins by other means. Regardless, the specificity is essential to avoid steroids promoting behaviors that are incompatible with parenting, such as mating or aggression."

https://www.science.org/doi/full/10.1126/science.adk2495?utm_source=sfmc&utm_medium...

Comment: this should be viewed from the standpoint of purposeful design, as the intricacies of the hormonal actions are so precise in their controls. With so many organs needing preparation (uterus, breasts, brain) how does chance evolution organize this birth event? It cannot.