Name: VINICIUS MENEGARDO NUNES
Publication date: 22/06/2020
Advisor:
Name |
Role |
|---|---|
| LUIZ CARLOS SCHENBERG | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| LUIZ CARLOS SCHENBERG | Advisor * |
Summary: The main feature of panic disorder (PD) is the recurrence of unexpected panic attacks (PA), with symptoms such as shortness of breath, tachycardia, sweating, tremors, fear of dying, among others. Klein (1993) presented the suffocation false alarm theory to explain PD. This theory proposes the existence of a suffocation monitor, which integrates several signs of asphyxia, and which can activate a suffocation alarm system when a potential suffocation is identified. Spontaneous PAs would occur as a result of an erroneous physiological interpretation by this monitor, triggering the suffocation alarm system even under normal conditions. On the other hand, Deakin and Graeff (1991) proposed that the lack of serotonergic inhibition in the neuronal circuits that integrate defense reactions to proximal threats in periaqueductal gray (PAG) would be responsible for the occurrence of unexpected PAs. Several studies, both in humans and in animal models, have supported that there is a convergence between these two propositions. Objective: To investigate the responses of rats in suffocation tests and the role of caudoventrolateral PAG (cvlPAG) in the escape response of rats in an environmental hypercapnia/hypoxia (HH) test. Methods: Hypoxia test (HO) or HH test were applied to male Wistar rats. In the last group, neurosurgery was performed to obtain lesions in the cvlPAG. Subsequently, the rats were tested again. Vertical jump and rearing behavioral responses were recorded. Results: During the HO test 25% of the animals showed a vertical jump response, while during the HH test 57% of the animals showed this behavior. The unilateral lesion in cvlPAG abolished the vertical jump response in 80% of the animals that initially exhibited this behavior. The frequency of the rearing behavior was higher in the habituation period than in the HH test period and was higher during the HH test compared to the HO test. Conclusion: Like other studies, these results support the suffocation false alarm theory and the role of PAG in the mediation of TP. Although the main role in the PA of the dorsal PAG is widely suggested, our data suggest that the suffocation monitor is located specifically in the cvlPAG. Thus, we suggest that cvlPAG is responsible for triggering the PA, while dorsal PAG is responsible for mediating subsequent responses.
