Biology subjects

Munn, R. G.

Publications and source records attributed to Munn, R. G..

2 recordsLinked to original sources

bioRxiv2026

GLP-1 agonism alters local field potential in the lateral septum and alters operant behavior in rats

GLP-1 agonists are an emerging treatment for disorders of consumption. They are most prominent as treatments for obesity, but recent literature suggests that they are effective at reducing the consumption of all types of hedonic substances. This clearly suggests a central, cognitive, mechanism rather than a peripheral mechanism or an interaction with a single signalling pathway, but the specific site or sites for this mechanism remain to be discovered. Candidate brain regions for this reward-modulating activity have a relative paucity of GLP-1 receptors, with the exception of lateral septum, which expresses an abundance of them. In these experiments we recorded local field potential from lateral septum while animals received either saline control or the GLP-1R agonist liraglutide. We find that liraglutide significantly reduced the power of both high-frequency oscillations and theta rhythm in the lateral septum, suggesting that GLP-1R agonism changes how lateral septum communicates with its network. In addition, we show that liraglutide causes animals to wait longer to respond for reward in a differential reinforcement of low rates paradigm. Together, these results suggest that a primary region in the control of the anticonsumptive action of GLP-1 agonists is the lateral septum, and that the coding of reward by this region is a central node in the network responsible for cognition about and behaviour with respect to reward.

neuroscience↗

bioRxiv2020

Disordered phasic relationships between hippocampal place cells, theta, and gamma rhythms in the Ts65Dn mouse model of Down Syndrome

Down Syndrome (DS) in humans is caused by trisomy of chromosome 21 and is marked by prominent difficulties in learning and memory. Decades of research have demonstrated that the hippocampus is a key structure in learning and memory, and recent work with mouse models of DS have shown changes in spectral coherence in the field potentials of hippocampus and regions important for executive function such as prefrontal cortex. One of the primary functional differences in DS is thought to be an excess of GABAergic innervation from Medial Septum (MS) to regions such as hippocampus. In these experiments, we probe in detail the activity of region CA1 of the hippocampus using in vivo electrophysiology in the Ts65Dn mouse model of DS in comparison to their non-trisomic 2N littermates. We find changes in hippocampal phenomenology that suggest that MS output, which drives theta rhythm in the hippocampus, is strongly altered. Moreover, we find that this change affects the phasic relationship of both CA1 place cells and gamma rhythms to theta. Since the phasic relationship of both of these aspects of hippocampal phenomenology to theta are thought to be critical for the segregation of encoding and retrieval epochs within hippocampus, it is likely that these changes are the neural substrates of the learning and memory deficits seen both in human DS and animal models such as Ts65Dn.

neuroscience↗