For the past 25 years, Dr. Andras Hajnal's research has focused on the neural mechanisms of appetitive behaviors, such as hedonic eating, substance use and addiction. Specific areas of his research have investigated how diet-induced obesity produces changes in the brain’s taste and reward systems to perpetuate over-eating and the role of gut-brain factors in regulating reward-guided behaviors.

Dr. Hajnal's early work was the first to demonstrate that sweet taste is sufficient to stimulate dopamine release in the nucleus accumbens. Dr. Hajnal’s work has also documented that reward elicited by sweet tastes is relayed through the parabrachial pontine nucleus to the forebrain and development of obesity impairs gustatory processing in the hindbrain. 

Recently, as part of a collaboration with bariatric surgeons and NIH scientists at NIAAA and NIDA, Dr. Hajnal has developed animal models of various bariatric surgeries for studying the beneficial and adverse effects of gastrointestinal manipulations on alcohol and opioid self-administration. The idea of using bariatric surgical animal models as a preclinical research tool to study neuro-hormonal mechanisms of addiction is novel and based on the premise that understanding what causes the switch in patients post-surgery moving away from food cravings and food addiction to develop alcohol and substance (primarily opioid) use disorder (a.k.a. ‘addiction-transfer’) could help with identifying mechanisms and targets in the brain that could be exploited in developing novel pharmacological targets to combat addiction.

A second area of research, currently funded by a Department of Defense Grant, is aimed at better understanding the mechanisms of gastrointestinal neuropeptide signaling in an animal model of spinal cord injury following weight loss surgery.