Does Intrarectal Administration of Christensenella minuta DSM22607 Impact Body Weight?

Background: Christensenella minuta (C. minuta) is a promising next-generation probiotic linked to reduced body weight, inhibition of obesogenic processes, and enhanced metabolic profiles. However, the extent and persistence of these effects, particularly under varying dietary conditions, remain uncertain. Objective: This study aimed to examine the effects of intrarectal administration of C. minuta on body weight regulation in vivo under different dietary patterns, with or without antibiotic pretreatment, both during the intervention and over the long term. Particular emphasis was placed on exploring the interactions between C. minuta supplementation, dietary background, caloric intake, and body weight gain. Methods: A total of 180 CD1 mice (both sexes equally) were allocated into nine experimental groups based on diet, with and without C. minuta supplementation, and with and without antibiotic pretreatment. The bacterial suspension was administered intrarectally once a week for three consecutive weeks in the treatment groups. Body weight was monitored weekly, and food intake was recorded biweekly over the 12-week study period. Visceral fat mass was measured postmortem. Results: Groups treated with C. minuta with antibiotic pretreatment exhibited significantly lower body weight gain than the control groups during the intervention phase in both sexes, irrespective of caloric intake and dietary pattern, indicating that the reduced weight gain was attributable to the effect of C. minuta. Regarding long-term effects following the cessation of administration, sexual dimorphism was observed: while no lasting impact was found in males, the body weight gain inhibiting effect of C. minuta treatment persisted in females. Furthermore, females treated with C. minuta exhibited the lowest levels of visceral fat among all groups. Caloric intake was not significantly associated with body weight gain at any time point in this study. Conclusions: C. minuta exerts a transient, caloric intake-independent inhibitory effect on body weight gain. The absence of sustained effects highlights the necessity for continuous or optimized administration protocols to ensure the attainment of long-term benefits in the future. The results of this study support the hypothesis that C. minuta can act as a modulator of host metabolism and body composition, underscoring the significance of treatment duration in this process.