Effects of Prefrontal Cortical Inactivation on Neural Activity in the Ventral Tegmental Area

Abstract Objectives Gut microbes, including probiotics, can exert a wide range of effects on the host, such as influencing gastrointestinal function and, in some cases, brain function and behavior. Although long-term exposure to certain probiotics have also been shown to alter brain function via vagal communication routes, it is possible that probiotics may influence the brain more acutely, such as shortly after administration. Indeed, gastrointestinal stimuli can activate vagal-dependent brain reward pathways within minutes of induction. Therefore, this study aimed to examine the short-term effects of acute probiotic exposure on neural activity in the brain and gut. Methods CF-1 mice were divided into three groups: probiotic (109 CFUs Enterococcus faecium in 200 ul PBS), gavage control (200 ul PBS), control groups (handling only). These groups were further divided into 3 subgroups to evaluate the temporal effects of acute probiotic administration at 3, 5, and 7 hours after a single dose of probiotic. c-Fos immunohistochemistry was used as a marker of neural activity in multiple regions of the brain and gut suggested to be affected by probiotics. Results Preliminary findings suggest that c-Fos positive cell density in the dentate gyrus of the hippocampus and ventral tegmental area were unaffected by acute administration of E. faecium. Data collection of c-Fos density is underway in other brain areas (i.e., parabrachial nucleus, bed nucleus of the stria terminalis, caudate putamen, pontine nucleus, and solitary nucleus tract) as well as the intestines (i.e., duodenum, jejunum, ileum, cecum, proximal and distal colon). Conclusions While preliminary evidence indicates that the dentate gyrus and ventral tegmental area were unaffected within the initial hours after a single dose of E. faecium, many brain and gut areas remain to be analyzed. Together, these data may collectively provide insight into the immediate effects of probiotics on gut and brain activity. Funding Sources This work was supported by Iowa State University start-up funds.

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Protein appetite drives macronutrient-related differences in ventral tegmental area neural activity

10.1101/542340 ◽

2019 ◽

Cited By ~ 1

Author(s):

Giulia Chiacchierini ◽

Fabien Naneix ◽

Kate Zara Peters ◽

John Apergis-Schoute ◽

Eelke Mirthe Simone Snoeren ◽

...

Keyword(s):

Ventral Tegmental Area ◽

Neural Activity ◽

De Novo ◽

Rapid Development ◽

Protein Restriction ◽

Male Rats ◽

Balanced Diet ◽

Protein Status ◽

Ventral Tegmental

AbstractControl of protein intake is essential for numerous biological processes as several amino acids cannot be synthesized de novo, however, its neurobiological substrates are still poorly understood. In the present study, we combined in vivo fiber photometry with nutrient-conditioned flavor in a rat model of protein appetite to record neuronal activity in the ventral tegmental area (VTA), a central brain region for the control of food-related processes. In adult male rats, protein restriction increased preference for casein (protein) over maltodextrin (carbohydrate). Moreover, protein consumption was associated with a greater VTA response relative to carbohydrate. After initial nutrient preference, a switch from a normal balanced diet to protein restriction induced rapid development of protein preference but required extensive exposure to macronutrient solutions to induce greater VTA responses to casein. Furthermore, prior protein restriction induced long-lasting food preference and VTA responses. This study reveals that VTA circuits are involved in protein appetite in times of need, a crucial process for all animals to acquire an adequate amount of protein in their diet.Significance StatementAcquiring insufficient protein in one’s diet has severe consequences for health and ultimately will lead to death. In addition, a low level of dietary protein has been proposed as a driver of obesity as it can leverage up intake of fat and carbohydrate. However, much remains unknown about the role of the brain in ensuring adequate intake of protein. Here, we show that in a state of protein restriction a key node in brain reward circuitry, the ventral tegmental area, is activated more strongly during consumption of protein than carbohydrate. Moreover, although rats’ behavior changed to reflect new protein status, patterns of neural activity were more persistent and only loosely linked to protein status.

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