I thought I would share this image, which I took a while ago, but that I really like! This is a #pituitary gland where cells expressing a protein called proopiomelanocortin (POMC for short) have been coloured in green. You can see two groups of cells; a very packed band in the middle and some sparse cells on the sides. The first are called melanotrophs, and they are important in determining skin and fur colour. The sparse cells on the sides are called corticotrophs (and that's what I am studying at the moment!) and they are important for the response to #stress . They secrete an #hormone called ACTH which stimulates the production of the stress hormone cortisol from the adrenal gland. At the moment we are trying to understand what happens to this cells after the body is exposed to stress for a prolonged amount of time. #scicomm #biology #science #physiology #microscopy
@nicolaromano The adrenal, my favourite gland. I call it the marathon runner's gland since everything about adrenal secretion - both cortex and medulla - is needed for marathon performance. I guess those cells must hypertrophy or proliferate too during stress...
@schwiening Ohhh I like 'the marathon's runner gland'! I might steal that from you!
Yes there's some evidence that chronic stress can cause hyperplasia of the adrenal, although in the long term it can also cause it to lose its function. It is a delicate balance!
@schwiening Good question! There does not seem to be stress-induced proliferation in corticotrophs, at least for acute stress. I think much of the control happens at the level of production and secretion of the hormone. In general, only a minimal % of the available hormone in each corticotroph is secreted in response to a stress, so the capacity of the gland is way way higher than what is normally needed.
If you think about it, it does make sense as stress is generally not something that is expected or that you can predict, so you need to have the ability to respond immediately, without having to wait for the hormone to be produced.
Some of my colleagues have recently written an article about this, which you might find interesting: https://academic.oup.com/endo/article/163/8/bqac089/6609891
The situation is slightly different for chronic stress where, depending on the strength of such stress, some proliferation might indeed happen.
@nicolaromano I was considering more the corticotrophs that secrete ACTH - do they proliferate and or hypertrophy? I talk about the HPA in my first lectures to the new Medical and Vet students - but, I know very little about how dynamic the pituitary is in terms of growth. We tend to think of feedback in terms of faster mechanisms than hypertrophy, but perhaps hyperplasia and hypertrophy are the way pituitary output capacity are modulated too?