To determine if IFNγ is necessary for antidepressant-induced increases in p11 expression, which comparison is most relevant?

• A. Expression levels in wild-type mice versus a control group
• B. Expression levels of p11 in wild-type mice versus IFNγ knockout mice, both treated with an SSRI
• C. Comparison of untreated wild-type mice and treated knockout mice
• D. Expression levels in all mouse strains regardless of treatment

Answer: (B)

The best approach to determine if IFNγ is necessary for antidepressant-induced increases in p11 expression is to compare the expression levels of p11 in both wild-type mice and IFNγ knockout mice, with both groups treated with an SSRI. This comparison is essential because it enables the investigation of whether the absence of IFNγ influences the impact of the antidepressant on p11 expression.

In this context, wild-type mice possess the normal functioning gene coding for IFNγ, which serves as a control for the expected response to the SSRI. The knockout mice, lacking the IFNγ gene, help establish whether this cytokine plays a critical role in mediating the antidepressant’s effects. If the SSRI leads to an increase in p11 expression only in the wild-type mice and not in the knockout mice, it would support the conclusion that IFNγ is necessary for the antidepressant-induced increases in p11.

The other options do not provide the correct context for this determination. For instance, comparing expression levels in a wild-type group versus a control group does not directly evaluate the role of IFNγ. Similarly, comparing untreated wild-type mice and treated knockout mice does not isolate the effects of the SSRI in relation to the