Date of Completion


Document Type

Honors College Thesis


Psychological Sciences

Thesis Type

College of Arts and Science Honors, Honors College

First Advisor

Sayamwong Hammack


anxiety, sex differences, BNST, PACAP, estrous cycle, hormones


Previous studies have provided strong evidence that the bed nucleus of the stria terminalis (BNST) is involved in anxiety behavior expression following chronic exposure to stressful stimuli. Pituitary adenylate cyclase-activating polypeptide (PACAP) mediated signaling has been linked to the regulation of anxiety related behavior within this region. PACAP functioning appears to be linked to sex, with PACAP blood levels being strongly correlated with post-traumatic stress disorder (PTSD) diagnosis and symptoms in female humans (Ressler et al., 2011). The goal of this study was to further explore this sex specific association by examining anxiety behaviors across the estrous cycle in relation to the presence or absence of PACAP in the BNST. This line of inquiry was examined using free cycling non-ovariectomized female rats at various stages of the estrous cycle that were intracranially injected with either PACAP or a vehicle. Anxiety behaviors were operationalized by categorizing responses in an elevated plus maze. Significantly higher instances of anxiety-like behaviors were observed in female rats injected with PCAP during proestrus and estrus, phases in which ovarian hormones are fluctuating. Thus, the findings of this experiment lend credence to the idea that sex hormones interact with the BNST in a manner that can lead to amplified anxiety-like behaviors. Further investigation of this relationship is warranted in order to further understand apparent sexual dimorphism in the display of anxiety-related disorders, such as PTSD.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.