Microbiota‐gut‐brain axis as a regulator of reward processes

Abstract

The reward system is a set of neuronal structures responsible for the processing of a number of psychological components, such as 'wanting', 'liking' and associative learning (Berridge & Robinson, 2003).These three processes occur together, 'wanting' dominates the initial appetitive phase, 'liking' dominates the consummatory phase, and learning occurs through the reward-behavioural cycle (Berridge et al., 2016). Both phenomena are underpinned by different brain circuits and neurotransmitter systems. The 'wanting' component is largely controlled by the dopaminergic system, whereas the 'liking' component is thought to be more mediated by opioid and GABAergic systems (Berridge & Robinson, 2003). The neural circuitry constituting the anatomical and neurochemical substrate for reward and pleasure was described several decades ago by Olds and Milner, who, after implanting electrodes in certain areas of the central nervous system (CNS) and administering electrical microstimuli, demonstrated a pleasure response in the animals (Olds and Milner 1954).Following this, it was proposed that the monoaminergic activity could underlie the neurochemical basis of pleasure, with the monoaminergic system playing an important role in drug reinforcement

Decoding the Role of Gut-Microbiome in the Food Addiction Paradigm

“…In addition, over recent decades, a new decisive player has emerged in this equation [ 57 ]. Living gut microorganisms and their bioactive metabolites, including short-chain fatty acids (SCFAs) and conjugated fatty acids among others, and their neuroactive metabolites, such as serotonin (5-hydroxytryptamine; 5-HT) and γ-aminobutyric acid (GABA), are released in the bloodstream and can modulate the CNS directly or indirectly by affecting the ANS [ 58 , 59 , 60 ]. Hence, changes in enteric neuron activity will be perceived by the vagus nerve to modulate, among other physiological aspects, appetite, satiety, stress, and mood.…”

“…However, fewer studies have been conducted to answer how the microbiota might influence addiction-related behaviors, such as “food/eating addiction”. Even though the research to date is not complete, increasing evidence shows how microbiota dysbiosis is implicated in the development of these maladaptive habits [ 8 , 10 , 58 , 168 , 169 , 170 , 171 , 172 ] ( Figure 3 ). Considering this, all factors affecting the “healthy” composition of the GM, including host genetics [ 173 , 174 ], diet [ 175 , 176 ], age [ 177 , 178 ], mode of birth [ 179 , 180 ], and antibiotics intake [ 181 , 182 ], among others, can shape GM and ultimately trigger an abnormal eating behaviour.…”

Sodium Butyrate Protects Against Ethanol-Induced Toxicity in SH-SY5Y Cell Line

“…Gut microbiome plays an essential role in food digestion, xenobiotic metabolism, and regulation of innate and adaptive immunological processes (Bishehsari et al 2017 ; Cryan et al 2019 ). Indeed, dysbiosis, a term representing a loss or reduction of beneficial bacteria and accumulation of pathogenic ones (Belizário and Faintuch 2018 ), has been associated with dysregulation of food intake and energy homeostasis (Romaní-Pérez et al 2021 ; Woźniak et al 2021 ) and implicated in a myriad of central nervous system (CNS) disorders such as anxiety and depression (Cryan et al 2019 ; Knudsen et al 2021 ; Poluektova et al 2021 ), stroke (Yamashiro et al 2021 ), multiple sclerosis (Ullah et al 2021 ), Parkinson’s disease (Tizabi et al 2021a ), autism (Kong et al 2021 ), schizophrenia (Kelly et al 2021 ), aging (Li et al 2021 ; van Krimpen et al 2021 ), cognitive dysfunction (Cryan et al 2019 ; Cowan and Cryan 2021 ; Li et al 2021 ), Alzheimer’s disease (Giovannini et al 2021 ; Jiang et al 2021 ), and even substance abuse (Meckel and Kiraly 2019 ; García-Cabrerizo et al 2021 ).…”

“…Dysbiosis due to alcohol abuse may be a contributing factor to AUD (Engen et al 2015 ; Bishehsari et al 2017 ). Thus, alcohol-induced changes in the gut microbiota may contribute not only to development of alcoholic liver disease, but also to a variety of CNS disorders (Engen et al 2015 ; García-Cabrerizo et al 2021 ). Indeed, it has been suggested that use of probiotic might be of potential use in prevention and treatment of alcohol-associated pathologies (Engen et al 2015 ; Lowe et al 2018 ; Rodriguez-Gonzalez and Orio 2020 ; Carbia et al 2021 ; Gupta et al 2021 ).…”

The Microbiome–Gut–Brain Axis, a Potential Therapeutic Target for Substance-Related Disorders

“…Studies show that there is a bidirectional communication system between gut microbiome and brain, which is known as the microbiomegut-brain axis (MGBA) (Dinan and Cryan, 2017). Increasing evidence revealed the role of intestinal microbial community in neuropsychiatric diseases (Burokas et al, 2015), including reward process and substance use disorders (Garcia-Cabrerizo et al, 2021). It has been found that the composition and diversity of gut microbiome in substance-addicted individuals changed remarkably (Meckel and Kiraly, 2019).…”