Steven Crane Compiled Section Handouts. Human Behavioral Biology 2012

Binding globulin (chaperone proteins) levels determine its availability to act on cells

^o Example of gestational diabetes during pregnancy. High estrogen causes high GC binding globulin availability causes low GC availability causes high GC production due to lack of negative feedback. When high GC production overshoots, you end up with high blood glucose which is gestational diabetes.

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  By itself, GCs do nothing to BP. But synergize with SNS input to skyrocket BP.
  

How does negative feedback work in these systems? 3 ways:

1. Amount of peripheral hormone work as negative feedback in the brain.

   • Often not in the hyp itself, but upstream.

2. But it's also about the ratio between hormones sometimes

3. And it's also about the rate of hormone increase sometimes

   • Rate often important in short-term feedback

   • Amount often important in longer-term feedback

What complexities do we have in how peptide and steroid hormones act?

• Peptide hormones acting on surface receptors can trigger messenger pathways that have big downstream effects deep inside the cell, including gene transcription which is often considered only the domain of steroid hormones.

• Steroid hormones usually act on intracellular receptors and modulate transcription.

• But also act outside (like progesterone with GABA)

• Also sometimes act not on DNA transcription directly (they can block TFs and such)

• Also the intracellular receptor can have a cofactor that causes the same steroid hormone binding to the same receptor (just with or without a co-factor) to have differential effects on gene transcription.

What hormone receptor complexities (just like NT receptors!) do we have?

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  Autoregulate receptor numbers in response to stimulation. Low stimulation -> upregulate receptors. High stimulation -> downregulate receptors.
  
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