Gonadal hormone deprivation regulates response to tibolone in neurodegenerative pathways.

Gonadal hormone deprivation (GHD) and decline such as menopause and bilateral oophorectomy are associated with an increased risk of neurodegeneration. Yet, hormone therapies (HTs) show varying efficacy, influenced by factors such as sex, drug type, and timing of treatment relative to hormone decline. We hypothesize that the molecular environment of the brain undergoes a transition following GHD, impacting the effectiveness of HTs. Using a GHD model in mice treated with Tibolone, we conducted proteomic analysis and identified a reprogrammed response to Tibolone, a compound that stimulates estrogenic, progestogenic, and androgenic pathways. Through a comprehensive network pharmacological workflow, we identified a reprogrammed response to Tibolone, particularly within "Pathways of Neurodegeneration", as well as interconnected pathways including "cellular respiration", "carbon metabolism", and "cellular homeostasis". Analysis revealed 23 proteins whose Tibolone response depended on GHD and/or sex, implicating critical processes like oxidative phosphorylation and calcium signalling. Our findings suggest the therapeutic efficacy of HTs may depend on these variables, suggesting a need for greater precision medicine considerations whilst highlighting the need to uncover underlying mechanisms.

Respirasome Proteins Are Regulated by Sex-Hormone Interactions in the Brain.

The existence of sex differences in disease incidence is attributed, in part, to sex differences in metabolism. Uncovering the precise mechanism driving these differences is an extraordinarily complex process influenced by genetics, endogenous hormones, sex-specific lifetime events, individual differences and external environmental/social factors. In fact, such differences may be subtle, but across a life span, increase susceptibility to a pathology. Whilst research persists in the hope of discovering an elegant biological mechanism to underpin sex differences in disease, here, we show, for the first time, that such a mechanism may be subtle in nature but influenced by multiple sex-specific factors. A proteomic dataset was generated from a gonadectomized mouse model treated with Tibolone, a menopausal hormone therapy. Following functional enrichment analysis, we identified that Alzheimer's disease and the electron transport chain-associated pathways were regulated by sex-hormone interactions. Specifically, we identified that the expression of three respirasome proteins, NDUFA2, NDUFA7 and UQCR10, is significantly altered by compounding factors that contribute to sex differences. These proteins function in bioenergetics and produce reactive oxygen species, which are each dysregulated in many diseases with sex differences in incidence. We show sex-specific reprogrammed responses to Tibolone following gonadectomy, which primarily influence the expression of proteins contributing to metabolic pathways. This further infers that metabolic differences may underpin the observed sex differences in disease, but also that hormone therapy research now has potential in exploring sex-specific interventions to produce an effective method of prevention or treatment.

Identification of HMGCR, PPGARG and prohibitin as potential druggable targets of dihydrotestosterone for treatment against traumatic brain injury using system pharmacology.

BACKGROUND: Traumatic Brain Injury (TBI) has long-term devastating effects for which there is no accurate and effective treatment for inflammation and chronic oxidative stress. As a disease that affects multiple signalling pathways, the search for a drug with a broader spectrum of pharmacological action is of clinical interest. The fact that endocrine disruption (e.g hypogonadism) has been observed in TBI patients suggests that endogenous therapy with testosterone, or its more androgenic derivative, dihydrotestosterone (DHT), may attenuate, at least in part, the TBI-induced inflammation, but the underlying molecular mechanisms by which this occurs are still not completely clear. AIMS AND METHODS: In this study, the main aim was to investigate proteins that may be related to the pathophysiological mechanism of TBI and also be pharmacological targets of DHT in order to explore a possible therapy with this androgen using network pharmacology. RESULTS AND CONCLUSIONS: We identified 2.700 proteins related to TBI and 1.567 that are potentially molecular targets of DHT. Functional enrichment analysis showed that steroid (p-value: 2.1-22), lipid metabolism (p-value: 2.8-21) and apoptotic processes (p-value: 5.2-21) are mainly altered in TBI. Furthermore, being mitochondrion an organelle involved on these molecular processes we next identified that out of 32 mitochondrial-related proteins 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR), peroxisome proliferator activated receptor gamma (PPGARG) and prohibitin are those found highly regulated in the network and potential targets of DHT in TBI. In conclusion, the identification of these cellular nodes may prove to be essential as targets of DHT for therapy against post-TBI inflammation.

Prior maternal separation stress alters the dendritic complexity of new hippocampal neurons and neuroinflammation in response to an inflammatory stressor in juvenile female rats.

Stress during critical periods of neurodevelopment is associated with an increased risk of developing stress-related psychiatric disorders, which are more common in women than men. Hippocampal neurogenesis (the birth of new neurons) is vulnerable to maternal separation (MS) and inflammatory stressors, and emerging evidence suggests that hippocampal neurogenesis is more sensitive to stress in the ventral hippocampus (vHi) than in the dorsal hippocampus (dHi). Although research into the effects of MS stress on hippocampal neurogenesis is well documented in male rodents, the effect in females remains underexplored. Similarly, reports on the impact of inflammatory stressors on hippocampal neurogenesis in females are limited, especially when female bias in the prevalence of stress-related psychiatric disorders begins to emerge. Thus, in this study we investigated the effects of MS followed by an inflammatory stressor (lipopolysaccharide, LPS) in early adolescence on peripheral and hippocampal inflammatory responses and hippocampal neurogenesis in juvenile female rats. We show that MS enhanced an LPS-induced increase in the pro-inflammatory cytokine IL-1ß in the vHi but not in the dHi. However, microglial activation was similar following LPS alone or MS alone in both hippocampal regions, while MS prior to LPS reduced microglial activation in both dHi and vHi. The production of new neurons was unaffected by MS and LPS. MS and LPS independently reduced the dendritic complexity of new neurons, and MS exacerbated LPS-induced reductions in the complexity of distal dendrites of new neurons in the vHi but not dHi. These data highlight that MS differentially primes the physiological response to LPS in the juvenile female rat hippocampus.

Juvenile stress exerts sex-independent effects on anxiety, antidepressant-like behaviours and dopaminergic innervation of the prelimbic cortex in adulthood and does not alter hippocampal neurogenesis.

Stress, particularly during childhood, is a major risk factor for the development of depression. Depression is twice as prevalent in women compared to men, which suggests that biological sex also contributes to depression susceptibility. However, the neurobiology underpinning sex differences in the long-term consequences of childhood stress remains unknown. Thus, the aim of this study was to determine whether stress applied during the prepubertal juvenile period (postnatal day 27-29) in rats induces sex-specific changes in anxiety-like behaviour, anhedonia, and antidepressant-like behaviour in adulthood in males and females. The impact of juvenile stress on two systems in the brain associated with these behaviours and that develop during the juvenile period, the mesocorticolimbic dopaminergic system and hippocampal neurogenesis, were also investigated. Juvenile stress altered escape-oriented behaviours in the forced swim test in both sexes, decreased latency to drink a palatable substance in a novel environment in the novelty-induced hypophagia test in both sexes, and decreased open field supported rearing behavior in females. These behavioural changes were accompanied by stress-induced increases in tyrosine hydroxylase immunoreactivity in the prefrontal cortex of both sexes, but not other regions of the mesocorticolimbic dopaminergic system. Juvenile stress did not impact anhedonia in adulthood as measured by the saccharin preference test and had no effect hippocampal neurogenesis across the longitudinal axis of the hippocampus. These results suggest that juvenile stress has long-lasting impacts on antidepressant-like and reward-seeking behaviour in adulthood and these changes may be due to alterations to catecholaminergic innervation of the medial prefrontal cortex.

Role of Neuroglobin in the Neuroprotective Actions of Estradiol and Estrogenic Compounds.

Estradiol exerts neuroprotective actions that are mediated by the regulation of a variety of signaling pathways and homeostatic molecules. Among these is neuroglobin, which is upregulated by estradiol and translocated to the mitochondria to sustain neuronal and glial cell adaptation to injury. In this paper, we will discuss the role of neuroglobin in the neuroprotective mechanisms elicited by estradiol acting on neurons, astrocytes and microglia. We will also consider the role of neuroglobin in the neuroprotective actions of clinically relevant synthetic steroids, such as tibolone. Finally, the possible contribution of the estrogenic regulation of neuroglobin to the generation of sex differences in brain pathology and the potential application of neuroglobin as therapy against neurological diseases will be examined.

Network pharmacology identifies IL6 as an important hub and target of tibolone for drug repurposing in traumatic brain injury.

Traumatic brain injury (TBI) is characterized by a complex network of signals mediating inflammatory, proliferative and apoptotic processes during its acute and chronic phases. Current therapies mitigate damage and are mainly for palliative care and there are currently no effective therapies for secondary damage. This suggests a need to discover a compound with a greater spectrum of action that can control various pathological aspects of TBI. Here we used a network pharmacology approach to explore the benefits of tibolone, an estrogen and androgen receptor agonist with broader actions in cells, as a possible repurposing drug for TBI therapy. Using different databases we retrieved the targets significantly associated to TBI and tibolone, obtaining 2700 and 652, respectively. The top 10 GO enriched terms were mostly related to cell proliferation, apoptosis and inflammation. Following protein-protein functional analysis, the top connected proteins were related to kinase activity (MAPK1/14/3, AKT1 PIK3R1), apoptosis (TP53, CASP3), growth factors (EGFR), estrogen signalling (ESR1) and inflammation (IL6, TNF), with IL6 as an important signalling hub belonging to the top GO categories. Thus, we identified IL6 as a cellular node which we then validated using molecular mechanics-generalized born surface area (MMGBSA) and docking to explore which tibolone metabolite might interact with this protein. Both 3α and 3ß-OH tibolone seemed to bind better to IL6 at important sites responsible for its binding to IL6R. In conclusion, our study demonstrates key hubs involved in TBI pathology which indicates IL6 as a target molecule of tibolone as drug repurposing for TBI therapy.