Retell Lecture

A mother rat takes care of its pups, is by licking and grooming, nipple switching and arch back nursing. So the rats that do a lot of licking and grooming and the rats that do very little, but most rats are in between, so that resembles a human-human behaviour as well right? You have mothers that are highly mothering and my mother's that couldn't care less. And most mothers are somewhere in between. So if you look at these rats so all you do, you observe them and you put them in separate cages so you put the high lickers in one cage, not the mothers, but the offspring and the low lickers in another cage. And then you let them grow and their adults and their mothers are long buried. And you look in the brain and you see that those will have high licking mothers express a lot of glucocorticoid receptor gene. And those who are low licker express low, that reflects a number of receptors. And that results in a different stress response. But this is not the only difference. We found later on there are hundreds of genes that are differently expressed. So if you get a mutation, you know a polymorphism once in a million, here just the motherly love changes hundreds of genes in one shot and it changes them in a very stable way that you can look at the old rat. And you can say whether it was licked or not. But you can also say by behaviour. So if you want to the cages to the room, the rats that were poorly licked are highly anxious, hard to handle, aggressive. And and the rats that were very well handled as little pups. They are much more relaxed, much easier to handle. So you know, like every technician in the lab knows, looking at the adult rat, how it was licked when it was a little pup. And the question of course is, mechanism, how does this work?