Progesterone's Effects on Cognitive Performance of Male Mice Are Independent of Progestin Receptors but Relate to Increases in GABAA Activity in the Hippocampus and Cortex

Hormones and B-cell development in health and autoimmunity

The development of B cells into antibody-secreting plasma cells is central to the adaptive immune system as they induce protective and specific antibody responses against invading pathogens. Various studies have shown that, during this process, hormones can play important roles in the lymphopoiesis, activation, proliferation, and differentiation of B cells, and depending on the signal given by the receptor of each hormone, they can have a positive or negative effect. In autoimmune diseases, hormonal deregulation has been reported to be related to the survival, activation and/or differentiation of autoreactive clones of B cells, thus promoting the development of autoimmunity. Clinical manifestations of autoimmune diseases have been associated with estrogens, prolactin (PRL), and growth hormone (GH) levels. However, androgens, such as testosterone and progesterone (P4), could have a protective effect. The objective of this review is to highlight the links between different hormones and the immune response mediated by B cells in the etiopathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). The data collected provide insights into the role of hormones in the cellular, molecular and/or epigenetic mechanisms that modulate the B-cell response in health and disease.

Impact of NMDA receptors block versus GABA-A receptors modulation on synaptic plasticity and brain electrical activity in metabolic syndrome

PURPOSE

Metabolic syndrome (MetS) is a common disorder associated with disturbed neurotransmitter homeostasis. Memantine, an N-methyl-d-aspartate receptor (NMDAR) antagonist, was first used in Alzheimer's disease. Allopregnanolone (Allo), a potent positive allosteric modulator of the Gamma-Amino-Butyric Acid (GABA)-A receptors, decreases in neurodegenerative diseases. The study investigated the impact of Memantine versus Allo administration on the animal model of MetS to clarify whether the mechanism of abnormalities is related more to excitatory or inhibitory neurotransmitter dysfunction.

MATERIALS AND METHODS

Fifty-six male rats were allocated into 7 groups: 4 control groups, 1 MetS group, and 2 treated MetS groups. They underwent assessment of cognition-related behavior by open field and forced swimming tests, electroencephalogram (EEG) recording, serum markers confirming the establishment of MetS model and hippocampal Glial Fibrillary Acidic Protein (GFAP) and Brain-Derived Neurotrophic Factor (BDNF).

RESULTS

Allo improved anxiety-like behavior and decreased grooming frequency compared to Memantine. Both drugs increased GFAP and BDNF expression, improving synaptic plasticity and cognition-related behaviors. The therapeutic effect of Allo was more beneficial regarding lipid profile and anxiety. We reported progressive slowing of EEG waves in the MetS group with Memantine and Allo treatment with increased relative theta and decreased relative delta rhythms.

CONCLUSIONS

Both Allo and Memantine boosted the outcome parameters in the animal model of MetS. Allo markedly improved the anxiety-like behavior in the form of significantly decreased grooming frequency compared to the Memantine-treated groups. Both drugs were associated with increased hippocampal GFAP and BDNF expression, indicating an improvement in synaptic plasticity and so, cognition-related behaviors.

Gut Biogeography Accentuates Sex-Related Differences in the Murine Microbiome

Recent studies have highlighted the influence of factors such as sex and sex-linked hormones on microbiome composition, raising concerns about the generalizability of findings. Here, we explore whether gut geography, specifically the upper and lower gastrointestinal tract (GI), contributes to sex-linked microbiome differences in mice. We collected microbial samples throughout the length of the GI from male and female C57B6/J mice at 6- and 8-weeks old, and conducted 16S rRNA sequencing. Our findings revealed significant sex-related differences, with Clostridium_sensu_stricto_1 more abundant in the male colon, while females exhibited higher levels of Dubosiella newyorkensis across all organs at 6 weeks. We also observed decreased Shannon alpha diversity in the small intestine compared to the lower GI, and this diversity decreased further at 8 weeks. Interestingly, our results suggest that age mitigates sex-related, but not gut geography-related differences in beta diversity, with implications for experimental outcomes and treatment strategies. This study underscores the dynamic nature of microbial diversity, influenced by sex, age, and GI localization, emphasizing the need for a more comprehensive understanding of microbiome dynamics in experimental research and clinical interventions.

Neurosteroid Receptor Modulators for Treating Traumatic Brain Injury

Traumatic brain injury (TBI) triggers wide-ranging pathology that impacts multiple biochemical and physiological systems, both inside and outside the brain. Functional recovery in patients is impeded by early onset brain edema, acute and chronic inflammation, delayed cell death, and neurovascular disruption. Drug treatments that target these deficits are under active development, but it seems likely that fully effective therapy may require interruption of the multiplicity of TBI-induced pathological processes either by a cocktail of drug treatments or a single pleiotropic drug. The complex and highly interconnected biochemical network embodied by the neurosteroid system offers multiple options for the research and development of pleiotropic drug treatments that may provide benefit for those who have suffered a TBI. This narrative review examines the neurosteroids and their signaling systems and proposes directions for their utility in the next stage of TBI drug research and development.

Sex Differences in Cognition Across Aging

Sex and gender differences are seen in cognitive disturbances in a variety of neurological and psychiatry diseases. Men are more likely to have cognitive symptoms in schizophrenia whereas women are more likely to have more severe cognitive symptoms with major depressive disorder and Alzheimer's disease. Thus, it is important to understand sex and gender differences in underlying cognitive abilities with and without disease. Sex differences are noted in performance across various cognitive domains - with males typically outperforming females in spatial tasks and females typically outperforming males in verbal tasks. Furthermore, there are striking sex differences in brain networks that are activated during cognitive tasks and in learning strategies. Although rarely studied, there are also sex differences in the trajectory of cognitive aging. It is important to pay attention to these sex differences as they inform researchers of potential differences in resilience to age-related cognitive decline and underlying mechanisms for both healthy and pathological cognitive aging, depending on sex. We review literature on the progressive neurodegenerative disorder, Alzheimer's disease, as an example of pathological cognitive aging in which human females show greater lifetime risk, neuropathology, and cognitive impairment, compared to human males. Not surprisingly, the relationships between sex and cognition, cognitive aging, and Alzheimer's disease are nuanced and multifaceted. As such, this chapter will end with a discussion of lifestyle factors, like education and diet, as modifiable factors that can alter cognitive aging by sex. Understanding how cognition changes across age and contributing factors, like sex differences, will be essential to improving care for older adults.

Effect of Allopregnanolone on Spatial Memory and Synaptic Proteins in Animal Model of Metabolic Syndrome

Metabolic Syndrome (MetS) is considered a common disorder, especially with a sedentary lifestyle and unhealthy food consumption. Cognitive impairment is one of the MetS consequences that worsens the quality of life of the patients. The study aimed to assess the therapeutic effect of the neurosteroid Allopregnalonone on spatial memory and, therefore, the expression of two synaptic plasticity markers in the hippocampus. Thirty-two male rats were divided into four groups: control groups, MetS, and MetS + Allopregnalone. Spatial memory has been evaluated by the Y-maze task and blood pressure measured by the rat tail method. Biochemical evaluation of serum glucose, insulin, lipid profile, and hippocampal expression of Synaptophysin and Associated Protein 43 (GAP-43) were performed for assessing Allopregnanolone on serum and hippocampal markers. Allopregnanolone therapy improved working spatial memory, hypertension, and biochemical markers measured in the serum and hippocampus.