Effects of endocrine disruptors on the electrical activity of leptin receptor neurons in the dorsomedial hypothalamus and anxiety-like behavior in male mice

Social isolation promotes tumor immune evasion via β2-adrenergic receptor

Social isolation is a recognized risk factor for tumor initiation and mortality, but the role and mechanisms responsible for social isolation on tumor progression are poorly understood. In this study, we found that social isolation contributed to accelerated tumor growth and induced a remodeling of the tumor immune microenvironment, resulting in immunosuppression. Mechanistically, social isolation triggered the activation of the sympathetic nervous system, leading to impaired CD8+ T cell antitumor immune responses by activating β-adrenergic receptor 2 (β2-AR), which highly expressed on tumor-infiltrating CD8+ T cells. Pharmacological inhibition of β2-AR signaling effectively enhanced CD8+ T cell anti-tumor immune responses and improved the efficacy of anti-PD-1 immunotherapy in the context of social isolation. Thus, our study uncovers a mechanism through which social isolation induces tumor immune evasion and offers potential directions for cancer immunotherapy in socially isolated patients.

Investigating tributyltin's toxic effects: Intestinal barrier and neuroenteric disruption in rat's jejunum

The expansion of economic activities in coastal areas has significantly increased chemical contamination, leading to major environmental challenges. Contaminants enter the human body through the food chain, particularly via seafood and water consumption, triggering biomagnification and bioaccumulation processes. The gastrointestinal tract (GIT) acts as a selective barrier, protecting against chemical pollutants and maintaining homeostasis through a complex network of cells and immune responses. This study assessed impact of tributyltin (TBT), a highly toxic organometallic compound used in antifouling coatings for ships, on the GIT and myenteric neural plasticity in young rats. TBT exposure leads to histopathological changes, including epithelial detachment and inflammatory foci, especially at lower environmental doses. The study found that TBT causes significant reductions in villi height, increases in goblet cells and intraepithelial lymphocytes, and disrupts the myenteric plexus, with higher densities of extraganglionic neurons in exposed animals.

Effects of chronic high fat diet on mediobasal hypothalamic satiety neuron function in POMC-Cre mice

OBJECTIVE

The prevalence of obesity has increased over the past three decades. Proopiomelanocortin (POMC) neurons in the hypothalamic arcuate nucleus (ARC) play a vital role in induction of satiety. Chronic consumption of high-fat diet is known to reduce hypothalamic neuronal sensitivity to hormones like leptin, thus contributing to the development and persistence of obesity. The functional and morphological effects of a high-calorie diet on POMC neurons and how these effects contribute to the development and maintenance of the obese phenotype are not fully understood. For this purpose, POMC-Cre transgenic mice model was exposed to high-fat diet (HFD) and at the end of a 3- and 6-month period, electrophysiological and morphological changes, and the role of POMC neurons in homeostatic nutrition and their response to leptin were thoroughly investigated.

METHODS

Effects of HFD on POMC-satiety neurons in transgenic mice models exposed to chronic high-fat diet were investigated using electrophysiological (patch-clamp), chemogenetic and Cre recombinase advanced technological methods. Leptin, glucose and lipid profiles were determined and analyzed.

RESULTS

In mice exposed to a high-fat diet for 6 months, no significant changes in POMC dendritic spine number or projection density from POMC neurons to the paraventricular hypothalamus (PVN), lateral hypothalamus (LH), and bed nucleus stria terminalis (BNST) were observed. It was revealed that leptin hormone did not change the electrophysiological activities of POMC neurons in mice fed with HFD for 6 months. In addition, chemogenetic stimulation of POMC neurons increased HFD consumption. In the 3-month HFD-fed group, POMC activation induced an orexigenic response in mice, whereas switching to a standard diet was found to abolish orexigenic behavior in POMC mice.

CONCLUSIONS

Chronic high fat consumption disrupts the regulation of POMC neuron activation by leptin. Altered POMC neuron activation abolished the neuron's characteristic behavioral anorexigenic response. Change in nutritional content contributes to the reorganization of developing maladaptations.

Postweaning Social Isolation Alters Puberty Onset by Suppressing Electrical Activity of Arcuate Kisspeptin Neurons

INTRODUCTION

Postweaning social isolation (PWSI) in rodents is an advanced psychosocial stress model in early life. Some psychosocial stress, such as restrain and isolation, disrupts reproductive physiology in young and adult periods. Mechanisms of early-life stress effects on central regulation of reproduction need to be elucidated. We have investigated the effects of PWSI on function of arcuate kisspeptin (ARCKISS1) neurons by using electrophysiological techniques combining with monitoring of puberty onset and estrous cycle in male and female Kiss1-Cre mice.

METHODS

Female mice were monitored for puberty onset with vaginal opening examination during social isolation. After isolation, the estrous cycle of female mice was monitored with vaginal cytology. Anxiety-like behavior of mice was determined by an elevated plus maze test. Effects of PWSI on electrophysiology of ARCKISS1 neurons were investigated by the patch clamp method after intracranial injection of AAV-GFP virus into arcuate nucleus of Kiss1-Cre mice after the isolation period.

RESULTS

We found that both male and female isolated mice showed anxiety-like behavior. PWSI caused delay in vaginal opening and extension in estrous cycle length. Spontaneous-firing rates of ARCKISS1 neurons were significantly lower in the isolated male and female mice. The peak amplitude of inhibitory postsynaptic currents to ARCKISS1 neurons was higher in the isolated mice, while frequency of excitatory postsynaptic currents was higher in group-housed mice.

CONCLUSION

These findings demonstrate that PWSI alters pre- and postpubertal reproductive physiology through metabolic and electrophysiological pathways.

Cyhexatin causes developmental toxic effects by disrupting endocrine system and inducing behavioral inhibition, apoptosis and DNA hypomethylation in zebrafish (Danio rerio) larvae

Cyhexatin (CYT), an organotin acaricide, is extensively utilized in developing countries to mitigate plant diseases caused by mites and minimize agricultural crop losses. However, the comprehensive mechanisms underlying the developmental stage of non-target organisms remain largely unexplored. In this study, zebrafish embryos were firstly exposed to CYT (0.06, 0.12, and 0.20 ng/mL, referred to as CYTL, CYTM, and CYTH, respectively) from 2 hpf (hours post fertilization) to 30 dpf (days post fertilization). No developmental toxicity was observed in the CYTL and CYTM groups, except for induced deformed phenotypes in the CYTM group at 120 hpf. However, exposure to CYTH resulted in significant reductions in spontaneous movement (24 hpf), heart rate (48 hpf), hatching rate (48 and 72 hpf), body weight (30 dpf), whole body length (30 dpf), and locomotion (30 dpf). Additionally, CYTH exposure induced morphological malformations, including spinal curvature, pericardial edema, and tail curvature in zebrafish larvae. Moreover, CYTH treatment induced apoptosis, increased reactive oxygen species (ROS) production, and resulted in significant reductions in free T3, cholesterol, estradiol, and testosterone levels in zebrafish larvae, while free T4 levels were increased. RNA-Seq analysis indicated that CYTH exposure led to significant alterations in the genome-wide gene expression profiles of zebrafish, particularly in the thyroid hormone and steroid biosynthesis signaling pathways, indicating endocrine disruption. Furthermore, CYTH exposure induced global DNA hypomethylation, reduced S-adenosylmethionine (SAM) levels and the SAM/S-adenosylhomocysteine (SAH) ratio, elevated SAH levels, and suppressed the mRNA expression of DNA methyltransferases (DNMTs) while also downregulating DNMT1 at both the gene and protein levels in zebrafish larvae. Overall, this study partially elucidated the developmental toxicity and endocrine disruption caused by CYT in zebrafish, providing evidence of the environmental hazards associated with this acaricide.

Forced Swimming-Induced Depressive-like Behavior and Anxiety Are Reduced by Chlorpheniramine via Suppression of Oxidative and Inflammatory Mediators and Activating the Nrf2-BDNF Signaling Pathway

The first-generation antihistamine chlorpheniramine (CPA) is believed to have both anxiolytic and antidepressant properties. The current study sought to assess the mechanisms behind the antidepressant and anxiolytic effects of CPA therapy concerning oxidative stress, inflammation, and nuclear factor p45 for erythroid 2-Brain-derived neurotrophic factor (Nrf2-BDNF) signaling pathway in forced swimming-induced depressive-like behavior and anxiety. Eighteen male Wistar rats (180-200 gm) rats were separated into three groups (n = 6): a stressed group (acute stress) that underwent the forced swimming test (FST) and a stressed group that received pretreatment with CPA (10 mg/kg body weight) for 3 weeks (CPA + acute stress). Animals were subsequently put through the following behavioral tests after undergoing a forced swim test (FST) for 5 min: an immobility test, open field test, and elevated plus maze test. Serum cortisol levels were measured when the rats were euthanized at the end of the experiments. Brain neurotransmitters (cortisol, serotonin, and noradrenaline), oxidative stress (SOD and MDA), inflammatory (IL-6 and IL-1) biomarkers, and the Nrf2-BDNF signaling pathway in the hippocampus and cerebral cortex tissues was determined. CPA prevented stress-induced increases in cortisol levels (p < 0.0001), decreased brain neurotransmitters, and increased oxidative stress and inflammation. CPA also upregulated the Nrf2-BDNF signaling pathway. Thus, CPA mitigates depressive-like behavior and anxiety by inhibiting oxidative stress and inflammation and upregulating the Nrf2-BDNF signaling pathway in the brain tissues.

Effect of Methylphenidate on the onset of puberty and reproductive organ development in rats

Methylphenidate (MPH) is the first-line therapy for attention deficit hyperactivity disorder (ADHD) in children and adolescents. The aim of this study was to investigate the effects chronic MPH administration on reproductive parameters in both male and female pre-pubertal rats and reversibility of these effects. Sprague-Dawley rats were administered with 5 mg/kg MPH or saline orally from postnatal day (PND) 21 to PND60 and from PND21 to PND90. In addition, recovery groups from both sexes, in which MPH administration was stopped from PND60 to PND90 were included. Puberty onset, serum luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and estradiol levels were determined. Histopathology of male and female reproductive organs was examined. Puberty onset was significantly early in the males (p<0.01), but late in females (p<0.05). In males, serum LH and FSH levels were similar. Testosterone levels tended to decrease in MPH-treated animals. Morphology of testes, epididymis and vas deferens was disrupted in MPH-treated animals, while it was improved in the recovery group. In females, estradiol levels decreased in MPH-treated group compared to controls, and elevated LH levels were detected in recovery group. Similar to the males, disruption in the reproductive organ histology was seen with morphological deterioration in basement membrane of the ovaries of MPH-treated groups. These adverse effects of MPH were recovered after drug cessation for 30 days. The present results demonstrate that MPH could affect the reproductive functions in both male and female rats. However, our findings also suggest that those effects are transient.