Sorensen, D. B. | bioRxiv Science

bioRxiv2025

Refining the adjuvant-induced rat model of monoarthritis by optimizing the induction volume and injection site

Arthritis is a highly prevalent and disabling condition characterized by pathological joint-damage, clinical symptoms of pain and loss of normal joint function. Monoarthritis can be modelled in rodents via intraarticular injection of complete Freund's Adjuvant (CFA), inducing both joint inflammation and pain-like behaviours. This study aimed to compare the outcome of different injection-volumes and joint-locations, to refine the model's use and to improve its validity. Male and female rats were injected with CFA into the ankle (10, 20 or 50 {micro}l) or knee (10, 50 or 100 {micro}l), and assessed on dynamic weight bearing, locomotor activity, depressive- and anxiety-like behaviours, histology, and a variety of welfare and model-specific parameters. Induction of monoarthritis resulted in relatively similar behavioural profiles regardless of the injected joint. The animals were highly affected in the acute phase, while less in the chronic phase. Greater volumes of CFA were associated with more profound behavioural changes and joint swelling. The largest volumes induced a pronounced local spread of inflammation to adjacent joints, which was reduced with intermediate volumes without attenuating the model validity. Reducing induction volumes to 20 and 50 {micro}l CFA for ankle and knee injections, respectively, appears to be valuable refinement of these models.

neuroscience↗

bioRxiv2023

Investigating the Rescue Potential of Fecal Microbiota Transplants in Anorexia Nervosa using Antibiotic-treated Mice in a Split Group Cross-Over Study

Anorexia nervosa (AN) is a complex and serious mental disorder, which may affect individuals of all ages and sex, but primarily affecting young women. The disease is characterized by a disturbed body image, restrictive eating behavior, and a lack of acknowledgment of low body weight. The underlying causes of AN remain largely unknown, and current treatment options are limited to psychotherapy and nutritional support. This paper investigates the impact of Fecal Microbiota Transplants (FMT) from AN patients on food intake, body weight, behavior, and gut microbiota in antibiotic-treated mice. Two rounds of FMT were performed using AN and control (CO) donors. During the second round of FMT, a subset of mice received FMT from a different donor type. This split-group cross-over design was chosen to demonstrate any recovery effect of FMT from a healthy donor. The first FMT, from AN donors, resulted in lower food intake in mice without affecting body weight. After FMT2, serum analysis revealed higher levels of appetite-influencing hormones (PYY and leptin) in mice receiving AN-GM. Gut microbiota analysis showed significant differences between AN and CO mice after FMT1, before cross-over. Specific bacterial genera and families Ruminococcaceae, Lachnospiraceae, and Faecalibacterium showed different abundances in AN and CO receiving mice. Behavioral tests showed decreased locomotor activity in AN mice after FMT1. Overall, the results suggest that AN-GM may contribute to altered food intake and appetite regulation, which can be ameliorated with FMT from a healthy donor potentially offering FMT as a supportive treatment for AN.

microbiology↗