Stress exposure activates the HPA axis, influencing glucocorticoid secretion and behavior. The ADCYAP1 gene encodes PACAP, which regulates CRH and modulates stress responses. In 54 male Sprague Dawley rats, we examined temperament, brain ADCYAP1 expression, and circulating glucocorticoids. Our findings suggest that behavioral inhibition (BI) positively correlates with hypothalamic ADCYAP1. In contrast, social boldness (SB) negatively correlates with hippocampal ADCYAP1, while ADCYAP1 shows no correlation with CORT, despite BI and SB having a correlation. These results imply a possible role for ADCYAP1 in stable temperament traits and may indicate that gene expression is not determinative for these traits. Therefore, further analysis will be conducted.