Diabetes drug dulaglutide may reduce symptoms of depression

A recent Brain and Behavior study investigated the antidepressant effect of dulaglutide and the mechanism that underlies this effect.

Background

Depression is a chronic mood disorder that is associated with low mood, insomnia, weight loss, a state of unhappiness, aversion to activity, fatigue, and low self-esteem. According to the World Health Organization, depression has become one of the major health burdens across the world.

This mental health condition is commonly treated with an antidepressant that takes around a month to alleviate the symptoms. However, several side effects are associated with the use of antidepressant drugs and could be toxic at high doses.

A combination of psychological, genetic, and neurological factors contributes to the manifestations of depression. Even though the exact etiology of this mental health issue is not fully understood, research has shown chronic stress to be an inducer of depression. 

The hippocampus is a region of the brain that is associated with depression and modifies functionally and morphologically in response to stress. Animal model studies have shown that a decrease in neuronal and glial size, reduction in synaptic markers, loss of dendrites, and increase in apoptosis in the hippocampus leads to depression.

Many studies have uncovered the metabolic aspects of depression. For instance, diabetes and obesity are two common metabolic disorders that increase the risk of depression. Considering its high prevalence, novel therapies with high efficacy and fewer side effects are required to combat depression. The chronic mild stress (CMS) model has been recognized as a reliable rodent model to study depression. 

Glucagon-like peptide-1 (GLP-1) and its receptor agonists are involved with anti-inflammatory effects and neuroprotective activities and can improve mental disorders, particularly depression and cognition. GLP-1 is a peptide hormone that stimulates the secretion of insulin and restricts the synthesis of glucagon in the pancreas in a glucose-dependent manner. Liraglutide is a GLP-1 analog that exhibited a positive effect in reducing anxiety and depression symptoms.

Dulaglutide is a novel long-acting GLP-1 receptor agonist that improves cognitive dysfunction and neuronal damage in rats with vascular dementia. Although many studies highlighted the efficacy of dulaglutide in preventing depression-like behavior triggered by chronic social defeat stress (CSDS), the underlying mechanism of this effect is not clearly understood.

About the study

The current study used a metabolomics strategy to evaluate the effect of dulaglutide in a CMS model. Furthermore, the underlying mechanism of this effect was also assessed. Adult male ICR mice, which is a strain of albino mice, were selected for this study. All test mice were around seven weeks old.

After one week of acclimatization, 60 mice were randomly assigned in four groups, namely, control (CON), the CMS and Vehicle group (CMS+Veh), the CMS and 0.3 mg/kg dulaglutide group (Low Dula), and the CMS and 0.6 mg/kg dulaglutide group (High Dula). Except for the CON group, all other groups were exposed to stressors.

To establish the CMS model of depression, selected mice were exposed to two or three different stressors for 28 days continuously. For stress induction, mice were deprived of water and food for 12 hours, kept in wet bedding for 24 hours, kept in a tilted cage for 24 hours, pintail for 1 minute, and cold water treatment for five minutes. The body weight of each test mouse was measured weekly, and behavioral tests, such as the tail suspension test (TST), open field test (OFT), and forced swimming test (FST), were performed.

Study findings

The mice subjected to CMS for four weeks exhibited depressive- and anxiety-like symptoms. An LC-MS/MS metabolomics study was performed to understand the potential pathophysiological mechanisms and investigate the efficacy of drugs to alleviate depression-like symptoms.

A distinct difference between the CON group, CMS+Veh group, and High Dula group was observed in accordance with the metabolic disorders induced by chronic stress, which was altered through dulaglutide treatment. Many potential biomarkers were identified that are associated with purine metabolism, arginine and proline metabolism, glycerophospholipid metabolism, glutamate metabolism, sphingolipid metabolism, and bile secretion.

Lipid metabolism pathways could be potential targets through which dulaglutide alleviates depression. Lysophosphatidylcholine (LPC), phosphatidylethanolamine (PE), lysophosphatidylethanolamine (LPE), phosphatidylinositol (PI), sphingolipids, and phosphatidylcholine (PC), are involved with the therapeutic effect of dulaglutide in alleviating depression. Consistent with previous studies findings, this study highlighted the association between lipid metabolism and the antidepressant effect of dulaglutide.

The current study indicated the downregulation of N-acetyl-L-aspartic acid (NAA) in the CMS model group. NAA, which is one of the most important metabolites of the vertebrate nervous system, was found in decreased levels in rats with chronic, unpredictable, mild stress. However, the current study indicated that dulaglutide therapy increased the levels of NAA through its upregulation in the hippocampus.

In the CMS model group, an upregulation in L-glutamic acid and L-arginine was observed. Dulaglutide treatment caused a decrease in arginine and proline, thereby indirectly exhibiting a neuroprotective effect.

Conclusions

The current study highlighted the antidepressant effects of dulaglutide using the CMS depression model. Notably, the potential metabolisms that underlie the antidepressant effect of dulaglutide have been elucidated in this study. 

Story first appeared on News Medical