The impact of lactic acid and medium chain triglyceride on blood glucose, lactate and diurnal motor activity: A re-examination of a treatment of major depression using lactic acid

Incompatibility of antimalarial drugs: challenges in formulating combination products for malaria

Lipophilic drugs require more advance formulation, especially if the intention is to make solutions or semisolid formulations. This also accounts for most antimalarial drugs. Although some of these antimalarial drugs are soluble in lipid vehicles, few of them, such as lumefantrine (LF), are also poorly soluble in oily vehicles. Trying to dissolve and formulate LF as a liquid formulation together with other antimalarial drugs is, therefore, a major task. When mixed in solution together with artemether (AR), precipitation occurs, sometimes with LF precipitating out on its own, and sometimes with AR precipitating out alongside LF. In this study, it was hypothesized that the use of fatty acids could lead to enhanced solubility in lipid formulation. Addition of the fatty acid solved the dissolution challenges, making LF soluble for over a year at room temperature (21-23 °C); but further research is needed to test the mechanism of action of the fatty acid. In addition, design of experiments (MODDE® 13) revealed that the amount of fatty acid in the formulation was the only significant factor for LF precipitation.

Lactate: A New Target for Brain Disorders

Lactate in the brain is produced endogenously and exogenously. The primary functional cells that produce lactate in the brain are astrocytes. Astrocytes release lactate to act on neurons, thereby affecting neuronal function, through a process known as the astrocyte-neuron shuttle. Lactate affects microglial function as well and inhibits microglia-mediated neuroinflammation. Lactate also provides energy, acts as a signaling molecule, and promotes neurogenesis. This article summarizes the role of lactate in cells, animals, and humans. Lactate is a protective molecule against stress in healthy organisms and in the early stages of brain disorders. Thus, lactate may be a potential therapeutic target for brain disorders. Further research on the role of lactate in microglia may have great prospects. This article provides a new perspective and research direction for the study of lacate in brain disorders.

HSPA12A controls cerebral lactate homeostasis to maintain hippocampal neurogenesis and mood stabilization

Mood instability, a subjective emotional state defined as rapid mood oscillations of up and down, is a symptom that occurs in several psychiatric disorders, particularly major depressive disorder and bipolar disorder. Heat shock protein A12A (HSPA12A) shows decreased expression in the brains of schizophrenia patients. However, the causal effects of HSPA12A in any psychiatric disorders are completely unknown. To investigate whether HSPA12A affects mood stability, Hspa12a-knockout mice (Hspa12a-/-) and wild-type (WT) littermates were subjected to tests of open field, forced swimming, elevated plus maze, and sucrose preference. Cerebral lactate levels were measured in cerebrospinal fluid (CSF). Adult hippocampal neurogenesis (AHN) was assessed by BrdU labeling. We found that acute mood stress increased hippocampal HSPA12A expression and CSF lactate levels in mice. However, Hspa12a-/- mice exhibited behaviors of mood instability (anhedonia, lower locomotor activity, antidepression, and anxiety), which were accompanied by impaired AHN, decreased CSF lactate levels, and downregulated hippocampal glycolytic enzyme expression. By contrast, HSPA12A overexpression increased lactate production and glycolytic enzyme expression of primary hippocampal neurons. Intriguingly, lactate administration alleviated the mood instability and AHN impairment in Hspa12a-/- mice. Further analyses revealed that HSPA12A was necessary for sustaining cerebral lactate homeostasis, which could be mediated by inhibiting GSK3β in hippocampal neurons, to maintain AHN and mood stabilization. Taken together, HSPA12A is defined as a novel regulator of mood stability and exerts therapeutic potential for mood disorder. Our findings establish a framework for determining mood disorder and AHN relevance of cerebral lactate homeostasis. HSPA12A is a novel mood stabilizer through inhibiting GSK3β in hippocampal neurons, thereby sustaining glycolysis-generated lactate to maintain cerebral lactate homeostasis, which ultimately leading to maintenance of hippocampal neurogenesis and mood stabilization.

The anorectic and thermogenic effects of pharmacological lactate in male mice are confounded by treatment osmolarity and co-administered counterions

Lactate is a circulating metabolite and a signalling molecule with pleiotropic physiological effects. Studies suggest that lactate modulates energy balance by lowering food intake, inducing adipose browning and increasing whole-body thermogenesis. Yet, like many other metabolites, lactate is often commercially produced as a counterion-bound salt and typically administered in vivo through hypertonic aqueous solutions of sodium L-lactate. Most studies have not controlled for injection osmolarity and the co-injected sodium ions. Here, we show that the anorectic and thermogenic effects of exogenous sodium L-lactate in male mice are confounded by the hypertonicity of the injected solutions. Our data reveal that this is in contrast to the antiobesity effect of orally administered disodium succinate, which is uncoupled from these confounders. Further, our studies with other counterions indicate that counterions can have confounding effects beyond lactate pharmacology. Together, these findings underscore the importance of controlling for osmotic load and counterions in metabolite research.

Bifidobacterium spp. and their metabolite lactate protect against acute pancreatitis via inhibition of pancreatic and systemic inflammatory responses

Severe acute pancreatitis (SAP) is a critical illness characterized by a severe systemic inflammatory response resulting in persistent multiple organ failure and sepsis. The intestinal microbiome is increasingly appreciated to play a crucial role in modulation of AP disease outcome, but limited information is available about the identity and mechanism of action for specific commensal bacteria involved in AP-associated inflammation. Here we show that Bifidobacteria, particularly B. animalis, can protect against AP by regulating pancreatic and systemic inflammation in germ-free (GF) and oral antibiotic-treated (Abx) mouse models. Colonization by B. animalis and administration of its metabolite lactate protected Abx and GF mice from AP by reducing serum amylase concentration, ameliorating pancreatic lesions and improving survival rate after retrograde injection of sodium taurocholate. B. animalis relieved macrophage-associated local and systemic inflammation of AP in a TLR4/MyD88- and NLRP3/Caspase1-dependent manner through its metabolite lactate. Supporting our findings from the mouse study, clinical AP patients exhibited a decreased fecal abundance of Bifidobacteria that was inversely correlated with the severity of systemic inflammatory responses. These results may shed light on the heterogeneity of clinical outcomes and drive the development of more efficacious therapeutic interventions for AP, and potentially for other inflammatory disorders.

The regulatory effects of lactic acid on neuropsychiatric disorders

Lactic acid is produced mainly in astrocytes in the brain and serves as a substance that supplies energy to neurons. In recent years, numerous studies identified the potential effects of lactic acid on the central nervous system and demonstrated its role in regulating brain function as an energy metabolism substrate or cellular signaling molecule. Both deficiency and accumulation of lactic acid cause neurological dysfunction, which further lead to the development of neuropsychiatric disorders, such as Major depressive disorder, Schizophrenia, Alzheimer's disease, and Multiple sclerosis. Although an association between lactic acid and neuropsychiatric disorders was reported in previous research, the underlying pathogenic mechanisms remain unclear. Therefore, an in-depth understanding of the molecular mechanisms by which lactic acid regulates brain function is of significance for the early diagnosis and prevention of neuropsychiatric disorders. In this review, we summarize evidence that is focused on the potential mechanisms of lactic acid as a signaling molecule involved in the pathogenesis of neuropsychiatric disorders and propose a new mechanism by which lactic acid regulates brain function and disease through the microbiota-gut-brain axis to offer new insight into the prevention and treatment of neuropsychiatric diseases.

Synergistic Effects of Lotus Seed Resistant Starch and Sodium Lactate on Hypolipidemic Function and Serum Nontargeted Metabolites in Hyperlipidemic Rats

The synergistic effects of lotus seed resistant starch (LRS3) and sodium lactate (SL; a postbiotics of RS3) on hypolipidemic function and serum nontargeted metabolites of hyperlipidemia rats were investegated. Rats fed a high-fat diet were orally administered with LRS3 (HLRS group) or SL (HSL group) either alone or in combination (HLRSSL group) for consecutive 4 weeks. HLRSSL was found to control weight gain, regulate blood lipid levels, reduce accumulation of fat in liver cells, and improve lesions in rat cardiac arteries, liver, small intestine, and colon tissues more effectively compared to HLRS or HSL group alone. Compared to the high-fat control group (HMC), l-phenylalanine and LysoPC(22:6(4Z,7Z,10Z,13Z,16Z,19Z)) in serum were upregulated in HLRSSL rats, while aconitic acid and suberic acid were decreased. Correlation analysis showed that SM(d18:0/16:1(9Z)), taurochenodeoxycholic acid, LysoPC(22:6(4Z,7Z,10Z,13Z,16Z,19Z)), oleic acid, and retinol were negatively correlated with total cholesterol (TCHO), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) and positively correlated with high-density lipoprotein cholesterol (HDL-C). Moreover, glutamic acid and serine showed a significant positive correlation with LDL-C and negative correlation with HDL-C. These differential metabolites were associated with reducing serum lipid levels in hyperlipidemia rats potentially through metabolic pathways such as linoleic acid, glutamine and glutamate, pyruvate, citric acid cycle, and glycerophospholipid.