Map MSH secreted in response to leptin suppresses appetite a

Map MSH secreted in response to leptin suppresses appetite and increases metabolism. However, animals without the MSH precursor have increased metabolism and increased appetite 5.72 3.88 In a 2001 experiment by Stacy Forbes and colleagues, oblob mice were injected daily with one of the following 4 2.882.78 MSH MSH +leptin 3 control, injected with vehicle (buffered saline) only, no hormone The mice were allowed to eat at will. The plot at left shows the average weight gain for each group after 10 days. (Treatments are not labeled.) 2 How much more weight did the control mice gain than the mice treated with MSH only? That is, what is the difference in weight gain between the control mice and those treated with MSH only? 0 Treatments Data from Forbes et al. (2001) Proc Natl Acad Sci 98(7): 4233-4237 Number Which two of the following could also cause obesity in a mouse model? administering MSH to a normal mouse knocking out the gene for the leptin receptor inhibiting NPY activity inhibiting leptin transport across the blood-brain barrier overexpressing the MSH receptor on NPY neurons

Solution

on the research article by (Stacy fobes, 2001) the weight gain in 10 days was 5.72 ± 0.55 g in case of control i.e. vehicle treated ob/ob mice, under MSH treatment it was to 3.88 ± 1.06 g, leptin treatment it was 2.78 ± 0.62 g, while incase of the combined treatment of leptin and MSH analog it was at 2.88 ± 0.74 g.

So the amount the control mice gained more as compared to MSH treatment alone was = 5.72 - 3.88

= 1.84 g

The following will lead to obesity:

Knocking out the gene for leptin receptor, as leptin signal transduction cascade effects the level of MSH positively i.e. increases the secretion of Melanocyte stimulating hormone; which leads to decreased feeding leading to decrease in obesity. Hence reduced MSH Levels will lead to obesity

Inhibiting leptin transport across the blood brain barrier will also lead to obesity as it will reduce the MSH