A novel role for xenopsin: Stimulation of food intake

Apigenin attenuates LPS-induced neurotoxicity and cognitive impairment in mice via promoting mitochondrial fusion/mitophagy: role of SIRT3/PINK1/Parkin pathway

RATIONALE

Alteration of the NAD⁺ metabolic pathway is proposed to be implicated in lipopolysaccharide (LPS)-induced neurotoxicity and mitochondrial dysfunction in neurodegenerative diseases. Apigenin, a naturally-occurring flavonoid, has been reported to maintain NAD⁺ levels and to preserve various metabolic functions.

OBJECTIVES

This study aimed to explore the effect of apigenin on mitochondrial SIRT3 activity as a mediator through which it could modulate mitochondrial quality control and to protect against intracerebrovascular ICV/LPS-induced neurotoxicity.

METHODS

Mice received apigenin (40 mg/kg; p.o) for 7 consecutive days. One hour after the last dose, LPS (12 µg/kg, icv) was administered.

RESULTS

Apigenin robustly guarded against neuronal degenerative changes and maintained a normal count of intact neurons in mice hippocampi. Consequently, it inhibited the deleterious effect of LPS on cognitive functions. Apigenin was effective in preserving the NAD⁺/NADH ratio to boost mitochondrial sirtuin-3 (SIRT3), activity, and ATP production. It conserved normal mitochondrial features via induction of the master regulator of mitochondrial biogenesis, peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α), along with mitochondrial transcription factor A (TFAM) and the fusion proteins, mitofusin 2 (MFN2), and optic atrophy-1 (OPA1). Furthermore, it increased phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) and parkin expression as well as the microtubule-associated protein 1 light chain 3 II/I ratio (LC3II/I) to induce degradation of unhealthy mitochondria via mitophagy.

CONCLUSIONS

These observations reveal the marked neuroprotective potential of apigenin against LPS-induced neurotoxicity through inhibition of NAD⁺ depletion and activation of SIRT3 to maintain adequate mitochondrial homeostasis and function.

DNA methylation-modifiers reduced food intake in juvenile chickens (Gallus gallus) and Japanese quail (Coturnix japonica)

S-Adenosylmethionine (SAM) is the major endogenous methyl donor for methyltransferase reactions, while 5-Azacytidine (AZA) is a synthetic drug inhibiting DNA methyltransferase activity. Both molecules can thus influence DNA methylation patterns in an organism and thereby affect gene expression and ultimately behavior in the long-term. Whether or not effects on behavior are exerted on a shorter time scale is unclear. The goal of this study was to explore the direct effects of SAM and AZA on appetite regulation, using broiler chicken and Japanese quail as the animal models. Fed or 180 min-fasted broilers (at day 4 post-hatch) or 360 min-fasted quail (at day 7 post-hatch) were intracerebroventricularly injected with SAM or AZA and food intake was measured for 360 min. For broilers, there was no effect of AZA, at any dose, on food intake in either fed or fasted chicks at any time point. In contrast, 1 and 10 µg doses of SAM reduced food intake in fed chicks at 60 min post-injection. In fasted chicks, although there were no differences for the first 30 min post-injection, SAM suppressed food intake during the second 30-min period. For quail, however, AZA (25 µg dose) decreased food intake at 60 and 150-360 min post-injection in fasted birds. A reduction in food intake was also observed at 120- and 360-min post-injection in fed quail in response to 5 and 25 µg doses of AZA, respectively. SAM had no effect when quail were fasted, whereas 1 µg dose of SAM suppressed food consumption in fed quail during the third 30-min period. Thus, when administered directly into the central nervous system, SAM may act as a transient appetite suppressant in both broilers and quail, whereas the direct inhibitory effect of AZA on food consumption depends on species and nutritional states.

Neurotensin and Xenin Show Positive Correlations With Perceived Stress, Anxiety, Depressiveness and Eating Disorder Symptoms in Female Obese Patients

Objective

Neurotensin and xenin are two closely related anorexigenic neuropeptides synthesized in the small intestine that exert diverse peripheral and central functions. Both act via the neurotensin-1-receptor. In animal models of obesity reduced central concentrations of these peptides have been found. Dysregulations of the acute and chronic stress response are associated with development and maintenance of obesity. Until now, associations of both peptides with stress, anxiety, depressiveness, and eating disorder symptoms have not been investigated. The aim of the present study was to examine associations of neurotensin and xenin with these psychological characteristics under conditions of obesity.

Materials and Methods

From 2010 to 2016 we consecutively enrolled 160 inpatients (63 men and 97 women), admitted due to obesity and its mental and somatic comorbidities. Blood withdrawal und psychometric tests (PSQ-20, GAD-7, PHQ-9, and EDI-2) occurred within one week after admission. We measured levels of neurotensin and xenin in plasma by ELISA.

Results

Mean body mass index was 47.2 ± 9.5 kg/m². Concentrations of neurotensin and xenin positively correlated with each other (women: r = 0.788, p < 0.001; men: r = 0.731, p < 0.001) and did not significantly differ between sexes (p > 0.05). Women generally displayed higher psychometric values than men (PSQ-20: 58.2 ± 21.7 vs. 47.0 ± 20.8, p = 0.002; GAD-7: 9.7 ± 5.8 vs. 7.1 ± 5.3, p = 0.004; PHQ-9: 11.6 ± 6.6 vs. 8.8 ± 5.9, p = 0.008; EDI-2: 50.5 ± 12.8 vs. 39.7 ± 11.9, p < 0.001). Only women showed positive correlations of both neuropeptides with stress (neurotensin: r = 0.231, p = 0.023; xenin: r = 0.254, p = 0.013), anxiety (neurotensin: r = 0.265, p = 0.009; xenin: r = 0.257, p = 0.012), depressiveness (neurotensin: r = 0.281, p = 0.006; xenin: r = 0.241, p = 0.019) and eating disorder symptoms (neurotensin: r = 0.276, p = 0.007; xenin: r = 0.26, p = 0.011), whereas, men did not (p > 0.05).

Conclusion

Neurotensin and xenin plasma levels of female obese patients are positively correlated with perceived stress, anxiety, depressiveness, and eating disorder symptoms. These associations could be influenced by higher prevalence of mental disorders in women and by sex hormones. In men, no correlations were observed, which points toward a sex-dependent regulation.

Dietary macronutrient composition and central neuropeptide Y injection affect dietary preference and hypothalamic gene expression in chicks

OBJECTIVE

The objective of this study was to determine the influence of dietary macronutrient composition on central NPY's orexigenic effect in chicks.

METHODS

Day-of-hatch chicks were fed one of three diets (3000 kcal ME/kg) ad libitum from hatch: high carbohydrate (HC), high fat (HF; 30% ME derived from soybean oil), and high protein (HP; 25 vs. 22% CP). In Experiment 1, chicks received intracerebroventricular injections of 0 (vehicle), 0.2, or 2.0 nmol NPY on day 4 and food intake was recorded for 6 hours. In Experiment 2, chicks were given all three diets before and after injection. In Experiment 3, hypothalamus was collected at 1-hour post-injection for gene expression analysis.

RESULTS

The HC diet-fed chicks responded with a greater increase, while the chicks fed the HF diet had a lower threshold response in food intake to NPY. Neuropeptide Y dose-dependently increased food intake in chicks fed the HC and HP diets. Chicks administered 0.2 nmol NPY preferred the HC and HP diets over the HF diet. Relative quantities of hypothalamic NPYR1 and MC4R mRNA were reduced by NPY in chicks that consumed the HP and HC diets, respectively.

DISCUSSION

Consumption of the HC diet was associated with the most robust NPY-induced increase in food intake. Injection of NPY accentuated differences among dietary groups in hypothalamic gene expression of several appetite-associated factors, results suggesting that the NPY/agouti-related peptide and melanocortin pathways are associated with some of the diet- and NPY-induced differences observed in this study.