Date of Award


Document Type

Dissertation - Restricted

Degree Name

Doctor of Philosophy (PhD)


Biological Sciences

First Advisor

Elliot Stein

Second Advisor

Bela Piacsek

Third Advisor

Archie Vomachaka

Fourth Advisor

Donald Czech

Fifth Advisor

Brian Unsworth


The endogenous opioid peptides (EOPs) are a group of biologically active peptides with properties similar to the natural opiate alkaloids. There has been active investigation into the role of the EOPs in normal physiologic function and how alterations in activity of these peptides might contribute to different behavioral states. One putative function of the EOPs is to modulate reward quality information received by the brain. This hypothesis assumes that anatomically distinct system(s) exists in the mammalian brain that act to signal the reward value of sensory stimuli and that the EOPs may be involved in the activation or modulation of this system(s). In addition to their ability to act as reinforcers, the EOPs are also known to play a significant role in pain modulation. As such, the EOPs have been shown to be released from both pituitary and brain in response to several stressors. Further, since stress seems to produce an affective state opposite to that of reward, this dissertation investigated the involvement of the EOPs in the neural mechanisms of stress and reward.



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