Gut Hormones and Addiction Flashcards
Understand the neurobiology of food reward, with the ability to recall and describe the main brain regions involved in reward processing Understand the concept of food addiction Describe the effects of gut hormones and bariatric surgery on food reward Understand the role of gut hormones in other addictions, and how they could help in the treatment of addiction by modulating reward processing
Why is there an obesity epidemic?
A mismatch between easily available high-calorie food, the lack of need for exercise, and a genetic and physiological makeup designed to avoid starvation
State some internal cues for eating behaviour
Nutritional state, hormones, gender, gut cues
Name some brain regions activated in response to food
Orbitofrontal cortex and reward network (dorsal striatum, insula, nucleus accumbens, amygdala, substantia nigra, ventral tegmental area, lateral hypithalamus)
State the function of the amygdala
Emotional response
State the functions of the nucleus accumbens
Reward expectation and drive
State the functions of the dorsal striatum
Habits and learned associations
State the functions of the insula
Taste, multimodal integration, and decision making (risk-benefit)
Describe the differences in food cue responses in obese individuals
They have heightened responsivity to food cues, but on receiving the food have less brain activity - especially in the dorsal striatum and caudate
State some potential confounders in studies of obesity and food responses
BMI vs adiposity to define obesity, hormonal mediators not measured, BMI is not a behaviour measure, heterogeneity of the obese phenotype, fasted or fed nutritional state, choice of food and control pictures, differences in food preference, source of obese patients (e.g. wanting to lose weight/ dieting or not)
Food addiction is not a recognised psychiatric disorder. If it was, what would its prevalence be in those of healthy weight and overweight respectively? (Pursey et al, 2014)
Healthy weight: 11.1%
Overweight: 24.9%
Why is food addiction a controversial concept?
Food, unlike other addictive substances, is essential for life - other drugs of abuse hijack a system specifically designed for food, water, and sex. Food withdrawal is also not agreed on as existing.
Describe the differences between bariatric surgery patients who meet the hypothesised criteria for food addiction and those who do not
Those who meet criteria are more likely to have depression, anxiety, and binge eating disorder. There is no association with post-op weight loss, rehospitalisation, or attendance at follow-up appointments
Name the survey created by Gearhardt et al in 2011 to screen for food addiction
Yale Food Addiction Scale
State some behavioural components of addiction that could also seen in obesity
Compulsivity, impulsivity and risk-taking, stress and emotional response, reward sensitivity
Describe the influence of reward system activation on gut hormones
Reward system activation causes decreased in satiety hormones (leptin, insulin, GLP-1) and an increase in ghrelin, which increases appetite
How does exogenous ghrelin affect the response to food? (Goldstone et al, 2014)
It causes fasting-typical responses in the hedonic, orbitofrontal cortex, and hippocampal responses to food
How does chronic social defeat stress affect food intake in mice?
It leads to increased ghrelin, dopamine release, and an increase in high-fat food intake
How do GLP-1 receptor agonists affect food intake?
They reduce it in both lean and obese people
Name a GLP-1 receptor agonist licensed for weight loss
Liraglutide
What is the most effective bariatric surgery procedure?
Gastric bypass
Why might gastric bypass be more effective than gastric banding? (Scholtz & Goldstone, 2014)
It excludes the small bowel, which is believed to send signals that alter eating behaviour. Gastric bypass also increases levels of satiety gut hormones and bile acids, and lowers brain hedonic responses to food
Name a bariatric intervention developed due to the hormonal influences on food intake
Endobarrier
What affect do drugs have on gut hormones?
They increase ghrelin and GLP-1
Which system do GLP-1 analogues act on to reduce food intake?
Mesolimbic system
How does exogenous ghrelin affect alcohol intake? (Farokhnia et al, 2017)
It increases self-administration of alcohol and modulates brain activity in alcohol-dependent individuals
Describe the effect of a ghrelin receptor inverse agonist on alcohol intake (Lee et al, 2018)
It reduces the urge to drink
What form of ghrelin can bind to the ghrelin receptor?
Acetylated ghrelin
Name the enzyme which converts ghrelin to its active form
GOAT
Describe the effect of de-acetylated ghrelin on weight in humans (Allas et al, 2016)
It reduces it
