Mood disorders: A potential link between ghrelin and leptin on human body?

Abstract

Leptin and ghrelin are two hormones associated with multiple physiological functions, especially energy balance. Leptin is an adipocyte-secreted hormone discovered in 1950 and ghrelin which was found in 1999, is a peptide hormone produced and secreted in the stomach. A number of previous studies showed that these hormones could be associated with different types of mood disorders. The results of previous studies, nevertheless, are confounded by diverse sample selection and different methodologies. A search for related articles in the PubMed database was attempted. The search covered studies, reports, reviews and editorials published in the last ten years. Older references served as auxiliary sources for comparison purposes. However, due to the different results of the studies, there is a need for more investigation in order to establish the exact biochemical mechanisms that are responsible for these diseases and ghrelin's and leptin's effects on mood. Core tip: Mood disorders are affecting a major amount of the world population. Considering the multiple factors that are contributing in the development of mood disorders, this review emphasizes on the role of leptin and ghrelin hormones. These two hormones have a key role in energy balance but they also have an effect on other physiological functions too, therefore we emphasize on the recent findings which raise a potential link between the hormones and the disorders of mood.

The metabolic mind: A role for leptin and ghrelin in affect and social cognition

“…Affective states involve feelings of pleasure–displeasure (valence) and activation‐quiescence (arousal) and are thought to be fundamentally motivating for behavior. In line with this idea, we suggest that leptin and ghrelin may contribute to the generation of affect, as such affect would help motivate behaviors for energy intake and maintenance (Chuang & Zigman, ; Zarouna, Wozniak, & Papachristou, ). More specifically, the affective dimensions of metabolic states likely not only reinforce future appetitive behaviors as is already suggested (Dagher, ), but these feelings could also serve as an allostatic “barometer” (Duncan & Barrett, )—helping organisms identify when metabolic energy is low (e.g., feeling hungry and tired) vs. sufficient or in surplus (e.g., feeling full and energized).…”

Leptin and psychiatric illnesses: does leptin play a role in antipsychotic-induced weight gain?

“…Modifications of leptin metabolism and its gene expression, as well as its receptor, have been reported among patients with mental health disorders, independently to psychotropic drugs or in absence of antipsychotics [43]. Several studies showed a particular interest in the relationship between leptin and depressive disorders, but with discordant conclusions [42][43][44][45].…”

“…To begin, authors claiming that depression are associated with low leptin levels, thus suggesting a positive association/correlation between leptin levels and improvement in the depressive mood [43,45]. Indeed, pharmacological studies showed that intra-hippocampus administration of leptin can exert an antidepressant-like effect, thus demonstrating that leptin regulates dopaminergic neurotransmission in mesolimbic areas [45,46]. These studies on animal models found that leptin reduces symptoms of depression and had an anxiolytic effect through modulation of the hypothalamicpituitary-adrenal axis (HPA) [45,47].…”

“…Indeed, pharmacological studies showed that intra-hippocampus administration of leptin can exert an antidepressant-like effect, thus demonstrating that leptin regulates dopaminergic neurotransmission in mesolimbic areas [45,46]. These studies on animal models found that leptin reduces symptoms of depression and had an anxiolytic effect through modulation of the hypothalamicpituitary-adrenal axis (HPA) [45,47]. This axis is part of the networks that regulate mood, emotional behaviour as well as other specific functions like rewards processing [47,48].…”

Nutritional Factors, Physical Health and Immigrant Status Are Associated with Anxiety Disorders among Middle-Aged and Older Adults: Findings from Baseline Data of The Canadian Longitudinal Study on Aging (CLSA)

“…Researchers have suggested that anxiety disorders impair the regular functions of the hypothalamic-pituitary-adrenal (HPA) axis, causing an increase in appetite [76] due to alterations in the two hormones, ghrelin and leptin. Symptoms of anxiety have been reported to be negatively associated with levels of leptin [77,78], while ghrelin was found to have an anxiolytic effect in animal studies [79,80] following induced stress. Clearly, further research is needed to better understand the pathways that link obesity and anxiety.…”