C75 and the Expression of Hypothalamic Neuropeptides and other Metabolic Effects of C75

A study, again from Johns Hopkins University , examined the long-term effects of C75 in genetically obese mice (ob/ob) (Cha et al. 2004). C75 was found to prevent the up-regulation of orexigenic neuropeptides and down-regulation of anorexigenic neuropeptides despite drastically limiting caloric intake. The study also showed an increase in uncoupling protein 3 (UCP-3) expression, showing that C75 does increase the metabolism of treated animals. Also experiments were done with pair feed animals. These animals were fed the same amount of food as the C75-treated animals. There were some differences between the pair fed mice and the treated mice, confirming that C75 must alter metabolism and it is not just the reduced food intake that causes the profound weight loss. The pair fed mice exhibited typical characterizations of starvation. The treatment of C75 lowered plasma glucose and ketone bodies in the obese mice. After four weeks of treatment the treated mice were significantly leaner and more active. All of the experiments were done in ob/ob mice for 30 days.

C75 and glucose, triglycerides, free fatty acids, and ketone bodies. In figure 20 we can see that both the C75 and the pair fed mice had significantly lower levels of blood glucose than the control mice. Since the level of blood glucose in pair fed mice and the treated mice is about the same, the decline in blood glucose is attributed to the decreased food intak . C75 likely does not directly affect glucose levels. In figure 21 the triglyceride levels of C75 treated mice are similar to the control levels. C75 treatment does not result in significantly lower triglyceride levels that might be expected during starvation, indicating that C75 prevent the decrease of triglyceride that is present during low food intake. Similarly, to the lack of decreades triglyceride levels, the level of free fatty acids did not increase during the treatment of C75. During starvation, free fatty acids are mobilized for oxidation for energy. However, this does not occur when the mice are treated with C75. Ketone bodies rise when starvation is present, as seen in in the pair fed mice ( figure 21). The mice treated with C75 showed a slightly lower level of ketone bodies than event the control mice. The low level of ketone bodies and free fatty acids show that C75 does not activate starvation pathways. The (ob/ob) mice ate less, lost weight, and were in a physiologycaly fed-state.

C75 affects the expression of hypothalamic neuropeprides that control food intake. The mRNA levels for various neuropeptides were measure in the three groups of mice. Orexigens, NPY, MCH, and AgRP, were not unregulated in C75 mice as in the pair fed mice (figure 22). Thus the pair feed mice had starvation pathways activated, whereas C75 treated mice did not even though both types of mice ate the same amount of food. C75 does not activate starvation pathways. Likewise, C75 mice did not down-regulate anorexigenic neuropeptides. The levels of POMC and CART expression of C75 treated mice was similar to the control levels and greater than the pair fed levels (figure 23). The C75 mice were in a neurophysiological fed-state even though they ate as much as the pair fed mice.

Uncoupling Protein-3 (UCP-3) expression was increased in C75 treated mice. The expression of UCP-3 increased by about 40% of the control as can be seen in the increased levels of UCP-1 mRNA on figure 24. UCP-3 is involved in respiration. It uncouples oxidative phosphorylation resulting in heat generation. The upregulation of mRNA levels of UCP-3 with C75 treatment suggest that there is an increase in oxidative phosporylation. Thus this is further proog that C75 increases energy expenditure.

This study further confirms the early predictions about the mechanism of C75. It gives further insight into how C75 increases metabolism and how is affects metabolite levels. C75 prevents physiological starvation despite decreased food intake and increases energy expenditure.

Figure 19. Genetically obese mice (ob/ob). Mouse on right was treated with C75 for 30 days (Cha 2004).

 

Figure 20. Plasma glucose levels and free fatty acid levels of control mice, C75 treated mice and of pair-fed mice. Glucose levels oc C75 treated mice fall due to decreased food intake and free fatty acid levels do not rize due to decreased food intake (Cha 2004).

 

Figure 21. Plasma triglyceride and plasma ketone levels of control mice, C75 treated mice and of pair-fed mice. Triglyceride levels remain relatively unchanged in C75 mice and ketone levels slightly decrease (Cha 2004).

 

Figure 22. Orexigenic neuropeptide levels in C75 treated mice are not up-regulated, mRNA levels do not increase (Cha 2004).

Figure 23. Anorexigenic neuropeptides are not down regulated in C75 mice despite decreased food intake, mRNA levels do not decrease (Cha 2004).