## 4 Discussion
Recently, the anti-obesity properties of another lactic acid bacteria, _Latilactobacillus sakei_ CNTA 173, was also demonstrated using this in vivo model [27]. Interestingly, the administration of _L. plantarum_ CNTA 628 not only reduced lipid accumulation but also significantly extended the lifespan of _C. elegans_. Indeed, the probiotic reversed the detrimental impact of glucose on longevity (Figure 8) [73]. All these effects were independent of an effect over worm development, as was demonstrated by the presence of egg-laying and larval development at L1 stages in all supplemented and non-supplemented plates. Hence, we demonstrated how _L. plantarum_ CNTA 628 can reduce fat accumulation in _C. elegans_ without visibly affecting their development. This initial result led us to a more in-depth study of other health-benefiting effects of this probiotic. Previous studies have shown that certain probiotic strains are able to reduce the accumulation of reactive oxygen species (ROS) and the aging-related protein, lipofuscin [16; 36; 74]. Oxidative stress has been associated with the alteration of regulatory factors of mitochondrial activity, which in turn mediate the concentration of inflammatory markers associated with the development of new adipocytes, lipogenesis and, lastly, obesity [75]. These impairments in metabolic health are also closely related to a major risk factor in metabolic syndrome-related diseases, senescence. This factor is characterized by a growing chronic, low inflammatory profile that is also associated with the disfunction of the adipose tissue. Aging is associated with obesity, being one of the main risk factors for the development of this disease and its comorbidities. The use of _C. elegans_ as an animal model to study senescence and the causes and consequences of its early development has been widely approved [63; 76]. Some of the studies conducted in the field of probiotic supplementation have already stated that specific strains of _L. plantarum_ can modulate the accumulation of senescence-related markers and increase the worms' lifespan [16; 76]. In our study, supplementation with _L. plantarum_ CNTA 628 reduced ROS accumulation compared to the control NGMg group but also decreased the content in auto-fluorescent protein lipofuscin. Both conditions were studied under high-glucose conditions to ensure the physiological need of triggering an oxidative stress response and senescence, as described in previous works [36]. Putting these results together, we can hypothesize that _L. plantarum_ CNTA 628 supplementation is able to reduce lipoprotein accumulation and enhance the oxidative stress response, confirming the health-promoting effects of this probiotic strain in vivo. Due to the highly conserved gene ontology of _C. elegans_ compared with humans, it is considered a reliable model to evaluate the mechanisms behind the observed changes in physiological parameters [77]. Since previous works have described the effects that probiotics can have on the expression of genes involved in energy metabolism [22], we aimed to identify the underlying mechanisms of the phenotypical changes induced by this specific probiotic strain through gene expression analyses. No significant changes were detected in the expression of _daf-2_ and _daf-16_, two central genes involved in glucose metabolism, following probiotic treatment, suggesting that the mechanism under which _L. plantarum_ CNTA 628 promotes its health-promoting effects does not involve the IIS signaling pathway. A similar result was observed in FA biosynthesis-related genes _fat-1_ and _sbp-1_. However, genes encoding for n-3 fatty acid desaturase _fat-6_ and elongase _elo-2_ were significantly downregulated by the probiotic, while the expression of diacylglycerol acyl-transferase _dgat-2_ was downregulated under high-glucose conditions. On the other hand, long-chain fatty acyl-CoA synthetase-coding gene _acs-2_, the ortholog of human _FATP1_, appeared to be highly upregulated by _L. plantarum_ CNTA 628 in high-glucose conditions (Figure 8).