Perturbation of amygdala/somatostatin-nucleus of the solitary tract projections reduces sensitivity to quinine in a brief-access test

• Published in: Brain research 2022-05, Vol.1783, p.147838-147838, Article 147838
• Main Authors: Bartonjo, Jane, Masterson, Sean, St. John, Steven J., Lundy, Robert
• Format: Article
• Language: English
• Subjects: Amygdala; Amygdala - metabolism; Animals; Concentration-dependent licking; Female; Hedonic licking; Male; Mice; Nucleus of the solitary tract; Quinine - metabolism; Quinine - pharmacology; Solitary Nucleus - metabolism; Somatostatin; Somatostatin - metabolism; Sucrose - metabolism; Taste; Taste - physiology
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2022.147838

[Display omitted] •HSV-mediated gene transfer can target neuron types and their defined projections.•CeA/Sst-to-NST pathway activity was without effect on sucrose licking.•Inhibition of CeA/Sst-to-NST pathway increased licking to QHCl.•CeA/Sst-to-NST neurons must be active for normal aversion to QHCl. Neural processing in the nucleus of the solitary tract (NST) is critical for concentration-dependent intake of normally preferred and avoided taste stimuli (e.g. affective responding); and is influenced by descending input from numerous forebrain regions. In one region, the central nucleus of the amygdala (CeA), a subpopulation of neurons that project to the NST express the neuropeptide somatostatin (Sst). The present study investigated whether this CeA/Sst-to-NST pathway contributes to concentration-dependent intake of sucrose and quinine hydrochloride (QHCl) solutions using brief-access lick trials (5 s). In both female and male mice, we used virus-based optogenetic tools and laser light illumination to manipulate the activity of CeA/Sst neurons that project to the NST. During light-induced inhibition of CeA/Sst-to-NST neurons, mice licked significantly more to our three highest concentrations of QHCl compared to control mice, while sucrose intake was unaffected. Interestingly, light-induced activation of this descending pathway did not influence licking of either sucrose or QHCl. These findings suggest that the CeA/Sst-to-NST pathway must be active for normal affective responding to an exemplary aversive taste stimulus.