Del Mundo, Z. | bioRxiv Science

bioRxiv2026

Quantitative Neuropeptidomics Reveals Thermal Acclimation-Induced Remodeling of Peptidergic Signaling in the American Lobster Homarus americanus

Global warming and rising ocean temperatures pose substantial challenges to marine ecosystems and crustacean populations. As an ectothermic species, the American lobster (Homarus americanus) relies on physiological and neurochemical mechanisms to maintain homeostasis under varying environmental conditions. To elucidate the role of neuropeptides in neuronal plasticity and systemic adaptation to temperature fluctuations, we employed a quantitative mass spectrometry-based approach to probe key neuropeptides involving thermal adaptation in four lobster neural tissues at three temperatures: 4 {degrees}C (cold), 11 {degrees}C (control), and 18 {degrees}C (warm). Peptidomic profiling revealed a global reduction in peptide abundance during cold exposure, alongside coordinated, tissue-specific reconfigurations of the neuropeptidome between experimental groups. Cold exposure led to a significant downregulation of RFamide, leucokinin, and pyrokinin peptides in the commissural ganglia, whereas B-type allatostatin (AST-B), natalisin, and RYamide peptides were drastically elevated in the brain of warm-acclimated animals, with comparatively fewer detectable peptide abundance changes in the sinus gland and the stomatogastric ganglion. Collectively, our findings elucidate neuropeptide signaling pathways underlying thermal tolerance and adaptive resilience in Homarus americanus, offering insights into the survival mechanism and neurochemical basis of neural circuits in response to thermal acclimation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/710231v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@a3d24borg.highwire.dtl.DTLVardef@1434aaaorg.highwire.dtl.DTLVardef@db11cforg.highwire.dtl.DTLVardef@6e5995_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Toll-like Receptor 4 Contributes to PCOS-like Metabolic and Reproductive Pathogenesis

Polycystic ovary syndrome (PCOS) is a reproductive disorder with heterogeneous symptoms and severity. Despite extensive research documenting chronic immune dysfunction as a hallmark of PCOS, the specific molecular mechanisms driving immune activation and its connection to the syndromes diverse symptoms remain poorly understood. Emerging evidence suggests that gut-derived bacterial endotoxins, particularly lipopolysaccharide (LPS), may breach the intestinal barriers in PCOS patients and trigger systemic inflammation through Toll-like receptor 4 (TLR4), a pattern recognition receptor of the innate immune system. This study investigated whether TLR4 serves as a critical mechanistic driver of PCOS pathogenesis by examining the effect of genetic TLR4 knockout (TLR4-/-) in a letrozole (LET)-induced mouse model of PCOS. Our results demonstrate that TLR4 deficiency reduces many PCOS-like symptoms, including elevated luteinizing hormone, anovulation, and metabolic dysfunction. TLR4 knockout also preserved estrous cycling and fertility, improved glucose tolerance, maintained gut barrier integrity, and reduced inflammatory markers in LET-treated females. These findings establish TLR4 as a key mediator orchestrating PCOSs multi-system pathology, positioning TLR4 as a critical convergence point rather than affecting individual symptoms in isolation. This novel work reveals that TLR4-mediated inflammation drives multiple PCOS pathologies, opening avenues for targeted anti-inflammatory treatments in women with this disorder. Significance StatementPolycystic ovary syndrome (PCOS) affects up to 15% of reproductive-age women worldwide. This study reveals that TLR4, an innate immune receptor, is key to the pathophysiology of PCOS-like symptoms in female mice. When TLR4 was genetically deleted, mice treated with letrozole to induce PCOS-like symptoms maintained normal weight, glucose regulation, estrous cycling, and fertility. The improvements coincided with preserved gut barrier breakdown and reduced inflammation. These findings identify TLR4 as a key mediator between gut health, immune activation, and PCOS pathophysiology, suggesting that targeting TLR4 could offer new therapeutic approaches for this common but poorly understood syndrome affecting millions of women.

immunology↗