PhD Scientific Days 2021

NE_II_L: Neurosciences II. Lectures

The role of the calretinin positive neurons in the paraventricular thalamus in the rodent model of stress induced sleep disorder

Text of the abstract

Stress-related sleep disorders affect many people worldwide, however neuronal links between sleep and stress are presently unclear. Paraventricular thalamus (PVT) can potentially connect these two phenomena since the involvement of PVT in stress and wakefulness is well established. The aim of our present research is to investigate the role of DMT in stress-related sleep disorders. Earlier experiments by our research group have shown that graded optogenetic stimulation of PVT calretinin positive (PVT/CR+) cells can generate arousal (Mátyás et al., 2018). Based on these results, we investigated the effect of photoinhibition of PVT/CR+ cells on normal sleep and on sleep following a stressful situation.
Prolonged inhibition of PVT/CR+ cells at the beginning of the mice’ inactive phase led to a significant decrease in the EMG activity and movements of the mice and a concomitant increase in the power of sleep related delta activity in the EEG. Reduced arousal was maintained after terminating the inhibition. Prolonged inhibition of PVT/CR+ cells led to a 50% decrease in sleep onset. In the next step we used the same photoinhibition protocol following the exposure of mice to predator (fox) odor in a novel environment and studied the effect of post stress inhibition of PVT/CR+ cells on the development of stress induced sleep disturbances.
We have also started to record unit activity of these PVT/CR+ neurons and we found that the firing rate of these neurons is highly arosal state-dependent and increases significantly during the post stress days.
Our experiments demonstrated that optogenetic inhibition of the DMT/CR+ cells results in decreased vigilance, consistent with the proposal that these neurons are involved in the regulation forebrain arousal level. The involvement of DMT/CR+ cells in altered, stress related elevation of arousal level remains to be established.

University and Doctoral School

Semmelweis University, János Szentágothai Doctoral School of Neurosciences