Project Summary/Abstract
Female patients have increased pain sensitivity, increased risk for developing chronic pain, and increased
risk for adverse reactions to opioids. Despite these sex differences, many preclinical pain studies focus
solely on males. I will address this gap by investigating central pain circuitry in male and female mice, and
examine the role of circuitry sex differences in driving chronic pain.
The parabrachial nucleus (PB) and bed nucleus of the stria terminalis (BNST), two structures involved in
the affective processing of pain ( ‘unpleasant’ emotional perception of pain), share reciprocal connections.
Calcitonin gene related peptide (CGRP), a neuropeptide released from the PB in the BNST, is also linked
with affective pain processing. The BNST is a highly sexually dimrophic brain structure; it is possible that
sex differences in chronic pain susceptibility arise due to sex differences in BNST CGRP pain circuitry.
Consistent with this, my preliminary findings in mice show that CGRP differentially alters tonic BNST
inhibition in females versus males; CGRP decreases BNST inhibitory tone in females, and increases
BNST inhibitory tone in males. CGRP may exert its sex-dependent effect through KCC, a potassium /
chloride cotransporter, thereby regulating the inhibitory potential of GABA signaling. Additionally, PB
CGRP may be acting on different BNST subpopulations between males and females, including those that
project back to the parabrachial nucleus (aversive BNSTGlut¿PB and rewarding BNSTGABA¿PB). Whereas
PB CGRP inputs preferentially target inhibitory BNST neurons in males, my preliminary findings suggest
excitatory BNST neurons are preferentially targeted in females. Based on these findings, my hypothesis is
that PB CGRP release exerts sex-dependent effects on BNST projection neurons, such that CGRP
potentiates KCC2 to increase inhibition of BNSTGABA¿PB neurons in males, while inhibiting KCC2
to disinhibit BNSTGlut¿PB neurons in females. I will test predictions that corroborate this hypothesis
with three specific aims. First, I will determine whether sex-differences in CGRP’s effect on BNST
inhibitory tone are due to modulation of KCC2. Second, I will test whether PB inputs preferentially target
BNSTGABA¿PB neurons in males, and BNSTGlut¿PB neurons in females. Third, I will test whether BNST
CGRP signaling is causally involved in behavioral sex differences in chronic neuropathic pain. These aims
will clarify sex-differences in BNST CGRP signaling, and its role in the affective component of pain.
This project is part of a training plan designed to equip me with skills necessary for a career as a physician
neuroscientist. I will carry out this proposal under the mentorship of my Sponsor Dr. Asaf Keller, a sensory
perception expert, and thesis committee (Table 1), experts in pain and addiction. This mentoring team will
oversee my scientific development and facilitate my progess in achieving these aims and my career goals.