STRUCTURAL BASIS OF PEPTIDERGIC CONTROL OF AMYGDALA FUNCTIONS
Müller Kinga
János Szentágothai Neurosciences
Dr. Bereczki Dániel
MTA KOKI előadóterem
2023-09-25 13:00:00
Functional neurosciences
Dr. Sperlágh Beáta
Dr. Hájos Norbert
Dr. Mátyás Ferenc
Dr. Zachar Gergely
Dr. Csillag András
Dr. Puskár Zita
Dr. Rácz Bence
The amygdala nuclei located in the temporal lobe play an important role in the formation of fear behaviour and emotional memory. Uncovering its cell types and their connectivity is pivotal in understanding and treating amygdala-related diseases, e.g., anxiety and PTSD.
Based on their different developmental origin and functional roles, the amygdala can be divided into several nuclei, of which the basolateral, and central amygdala nuclei are the subjects of this thesis. The neuropeptide-expressing inhibitory neurons are abundant in all the mentioned nuclei and have a prolonged effect on their postsynaptic partners compared to the impact of the classical neurotransmitter-releasing neurons. Yet, their morphological features and connectome are still unexplored. Therefore, we examined the properties of inhibitory neurons expressing somatostatin, neuropeptide Y or cholecystokinin in these amygdala nuclei.
We separated two subtypes of inhibitory neurons expressing somatostatin, based on morphology and nitric oxide synthase content, although their firing patterns were similar. In addition, we distinguished three different subgroups of neuropeptide Y+ cells: neurogliaform cells with slower firing rate and dense axonal cloud were the most abundant cell type; fast-spiking neurons with smooth dendrites and neurons containing somatostatin with spiny dendrites were also identified in this neuropeptide-expressing group. 40% of cholecystokinin-containing inhibitory cells could be labelled by immunostaining against type 1 cannabinoid receptors. Surprisingly, some of the genetically labelled cholecystokinin expressing inhibitory cells had the properties of neurogliaform cells, fast-spiking basket or axo-axonic cells.
Finally, we examined the peptidergic input to the central amygdala from the dorsal tegmentum. We found that a fraction of the neurons expressing vasoactive intestinal polypeptide (VIP) in the dorsal tegmentum is dopaminergic both in mice and humans. Using viral tracing in mice we showed that these VIP neurons terminate solely in the two nuclei of the extended amygdala: central amygdala and bed nucleus of stria terminalis.
Based on the connectivity, neurons expressing the neuropeptides somatostatin, neuropeptide Y, cholecystokinin and VIP can contribute to controlling defensive behaviour by modifying the neuronal activity in amygdalar circuits.
