Date of Award
Master of Science (MS)
Department of Psychology
Byron A. Heidenreich
Panic disorder (PD) is a common mental illness characterized by recurring spontaneous panic attacks. Scientific investigation into PD has been accelerated by the development of rat models of PD. These models can be validated by responses to intravenous sodium lactate (NaLac), including tachycardia, that are similar to PD patient responses. Previous work on established PD models has suggested that antagonism of serotonin (5-HT) receptors in the basolateral amygdala (BLA) may be sufficient to model PD. To test this hypothesis metergoline (MET), a 5-HT receptor antagonist, or vehicle was microinjected into the BLA of anesthetized rats. Following the microinjection, NaLac or d-mannitol was infused intravenously. Heart and respiratory rates were recorded and analyzed for evidence of panic-like reactions.
Previous work suggests that 5-HT signaling in the BLA may influence the activity of neurons in the ventral pallidum (VP). Additionally, the VP may play a role in restraining anxiety-related behaviors. Concurrent with the previously described experiment, extra-cellular single unit recordings were made from the VP. The data were analyzed for changes in firing rate frequency as a result of the treatments.
The results indicated that only the rats treated with MET and NaLac exhibited tachycardia, confirming the utility of these treatments for modeling panic. Hypoventilation was observed in all d-mannitol treated rats, and hyperventilation was observed in all NaLac treated rats. This suggests respiratory rate is not a sufficient indicator of panic. Changes in VP activity were only observed in the rats treated with the vehicle and NaLac. Half of the subjects in that group exhibited firing rates at the end of the i.v. infusion > 150% of baseline; in comparison, none of the subjects treated with vehicle and d-mannitol exhibited firing rate increases of that magnitude. This supports the idea that the VP plays a role in restraining anxiety-related behaviors.
Schuweiler, Douglas Ryan, "Metergoline, the Basolateral Amygdala and the Ventral Pallidum: Implications for Panic Disorder" (2013). Theses and Dissertations. 66.