Serotonergic modulation of the BNST–CeA pathway reveals sex differences in fear learning.
Our collaboration with Nesha Burghardt’s lab is now out in Nature Neuroscience. This multifaceted work was valiantly led through all of its various stages of development by Becky Ravenelle with critical support from Jinah Lee and Carolina Fernandes-Henriques along the way. As always, a science projects travels down many paths, and our colleagues Jia Liu and Allyson Friedman were instrumental for making several important turns. An incredible team!
We dedicate the work to the memory of Carolina, who heartbreakingly left us before her time.
The Takeaway: Sex differences in the raphe–BNST–CeA pathway may contribute to the higher risk of PTSD in women.
What We Found: During fear learning, serotonin released in a region known as the bed nucleus of the stria terminalis (BNST) increases fear memory in females more than in males.
Serotonin stimulation in the BNST (c) during fear learning in females (d) and males (g), drives increased fear memory in females (e) but not in males (h) compared to controls.
We show that this is because the BNST is more easily activated by serotonin in females due to increased expression levels of the excitatory serotonin receptor 5HT2C in the BNST of females compared to males.
In females (c), cells in the the oval nucleus of the BNST are more active after serotonin stimulation during fear learning compared to controls, whereas in males (d), serotonin stimulation doesn’t change BNST activity after fear learning compared to controls that didn’t receive serotonin stimulation.
We demonstrate that serotonin release during fear learning leads to increased BNST communication with the central nucleus of the amygdala (CeA) during fear memory, which is carried out by oscillations in the high gamma range.
In the BNST of females, there is more transcription of the excitatory Htr2c than the inhibitory Htr1a receptor, whereas in males they transcription levels are more similar.
After serotonin stimulation, the fear cue evokes more oscillations in the high-gamma range in the BNST and CeA of females.
Females have more gamma synchrony in the BNST-CeA after serotonin stimulation (i) whereas males do not (j)