Feeding behavior is often separated into homeostatic and hedonic components. Hedonic feeding, which can be triggered by visual or olfactory food cues, involves brain regions that play a role in reward and motivation, while homeostatic feeding is thought to be under the control of circulating hormones acting primarily on the hypothalamus. Ghrelin is a peptide hormone secreted by the gut that causes hunger and food consumption. Here, we show that ghrelin administered intravenously to healthy volunteers during functional magnetic resonance imaging increased the neural response to food pictures in regions of the brain, including the amygdala, orbitofrontal cortex, anterior insula, and striatum, implicated in encoding the incentive value of food cues. The effects of ghrelin on the amygdala and OFC response were correlated with self-rated hunger ratings. This demonstrates that metabolic signals such as ghrelin may favor food consumption by enhancing the hedonic and incentive responses to food-related cues.

Monosodium glutamate is made up of nutritionally indispensable amino acids and used as flavour enhancer worldwide. Monosodium glutamate is believed to be associated with different health problems. This study is aimed to shed light on the available literature from last 25 years about different clinical trials which had been carried out on animal and human models regarding possible effects of monosodium glutamate. Google scholar, NCBI, PUBMED, EMBASE, Wangfang databases, and Web of Science databases were used to retrieve the available studies. Literature showed that monosodium glutamate was associated with adverse side-effects particularly in animals including induction of obesity, diabetes, hepatotoxic, neurotoxic and genotoxic effects. Different reports revealed increased hunger, food intake, and obesity in human subjects. Limited studies have been carried out on humans to check possible hepatotoxic, neurotoxic, and genotoxic effects of monosodium glutamate. Available literature showed that increased consumption of monosodium glutamate may be associated with harmful health effects. So, it is recommended to use common salt instead of it. Furthermore, intensive research is required to explore monosodium glutamate-related molecular and metabolic mechanisms.

Increased sugar-sweetened beverage consumption has been linked to higher rates of obesity. Using functional MRI, we assessed brain perfusion responses to drinking two commonly consumed monosaccharides, glucose and fructose, in obese and lean adolescents. Marked differences were observed. In response to drinking glucose, obese adolescents exhibited decreased brain perfusion in brain regions involved in executive function (prefrontal cortex [PFC]) and increased perfusion in homeostatic appetite regions of the brain (hypothalamus). Conversely, in response to drinking glucose, lean adolescents demonstrated increased PFC brain perfusion and no change in perfusion in the hypothalamus. In addition, obese adolescents demonstrated attenuated suppression of serum acyl-ghrelin and increased circulating insulin level after glucose ingestion; furthermore, the change in acyl-ghrelin and insulin levels after both glucose and fructose ingestion was associated with increased hypothalamic, thalamic, and hippocampal blood flow in obese relative to lean adolescents. Additionally, in all subjects there was greater perfusion in the ventral striatum with fructose relative to glucose ingestion. Finally, reduced connectivity between executive, homeostatic, and hedonic brain regions was observed in obese adolescents. These data demonstrate that obese adolescents have impaired prefrontal executive control responses to drinking glucose and fructose, while their homeostatic and hedonic responses appear to be heightened. Thus, obesity-related brain adaptations to glucose and fructose consumption in obese adolescents may contribute to excessive consumption of glucose and fructose, thereby promoting further weight gain.

Purpose Breast cancer is one of the rapidly increasing cancers among women and a significant cause of cancer-related morbidity and mortality worldwide. Therefore, the current study was designed to examine and compare trends of breast cancer incidence (BCI) during the observed period (1990–2015) in specific age groups and investigate age-specific, time period, and birth cohort-related effects on BCI in China, India, Pakistan, and Thailand. Patients and method Data related to BCI were retrieved from the Institute for Health Metrics and Evaluation. Age–period–cohort model joint with intrinsic estimator algorithm was used to estimate the effect of age, period, and birth cohort on BCI. BCI rates were analyzed among different age groups ranging from 20 to 84 years in specified periods. Result Overall, results showed an increasing trend of BCI among four Asian countries during the study period especially in age groups 50 to 84 years. Higher incidence rates were observed in 2015 in the age group 70–74, 65–69, 50–54, and 60–64 in Pakistan, China, India, and Thailand, respectively. Age period cohort analysis revealed significantly raised effect of age and period and declined effect of the cohort on incidence rates. Conclusion The current study reported increased BCI with time in selected four Asian countries. Overall, BCI remained high in Pakistan as compared to China, India, and Thailand. Although proper registries are not available in most of the developing Asian countries, the current study highlighted the increased incidence and may play an essential role in registries development or spreading awareness against this disease. Therefore, maintaining proper records to build registries at the national level along with advancements in breast cancer screening and treatment are highly recommended to deal with the increasing burden of this disease.

Highlights d fMRI reveals reward prediction error-related activity in dopamine projection sites d Intravenous ghrelin enhances food odor conditioning in human volunteers d Ghrelin also increases prediction error and value signals in striatum and hippocampus d Hippocampus-striatum functional connectivity is also increased by ghrelin

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The gut microbiome is comprised of various types of bacteria, fungi, protozoa, and viruses naturally occurring in humans and animals as normal microflora. Gut microorganisms are typically host specific, and their number and type vary according to different host species and environment. Gut microbes contribute directly and/or indirectly to various physiological processes including immune modulation, regulation of various neurotransmitter, and hormones, as well as production of many antioxidants and metabolites. They also play a role as antibiotic, antiinflammatory, anti-diabetic, and anti-carcinogenic agents. Moreover, the ability of gut microbes to attenuate various systemic diseases like coronary heart disease, irritable bowel syndrome, metabolic diseases like diabetes mellitus, and infectious diseases like diarrhea has recently been reported. Current research findings have enough evidence to suggest that gut microbiome is a new organ system mainly due to the microorganisms' specific biochemical interaction with their hosts and their systemic integration into the host biology. Investigations into the potential ability of gut microbiome to influence metabolism inside their host via biochemical interaction with antibiotics and other drugs has recently been initiated. This chapter specifically focuses on the importance of gut microorganisms as a new organ system.

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