Date of Completion


Thesis Type

College of Arts and Science Honors



First Advisor

Victor May

Second Advisor

Sayamwong Hammack


PACAP, Glutamate, Suprageniculate Nucleus, Medial Geniculate Nucleus, Auditory System


Pituitary adenylyl cyclase-activating polypeptide (PACAP) is a small pleiotropic neuropeptide found throughout the central and peripheral nervous system. It binds with highest affinity to its complementary receptor, pituitary adenylyl cyclase-activating polypeptide receptor 1. Using PACAP-Cre transgenic mice, an adeno-assisted viral construct was injected into the diencephalon for Cre-dependent expression of mCherry fluorescent protein in PACAP-expressing neurons. We observed red mCherry fluorescence in PACAP expressing neurons in the suprageniculate (SG) thalamic nucleus, a component of the auditory sensory pathway. The nucleus receives afferent fibers from the deep layers of the superior colliculus (SC) and sends axonal projections to various targets including the auditory cortex and posterior parietal cortex. Previous studies in hippocampal and limbic systems have shown that PACAP is co-expressed in glutamatergic neurons. In coherence, inspection of Allen’s Brain Atlas for vesicular glutamate transporter (VGLUT) and glutamic acid decarboxylase (GAD) transcript expression, as markers for glutamate and GABA neurons, respectively, suggests that the PACAP expressing neurons are glutamatergic in nature. The findings of this study are novel in identifying PACAP expression in an auditory relay nucleus.