Question

Which neuropeptide is antiinflammatory when activating the HPA axis but is proinflammatory when released locally by immune cells? a. \(\mathrm{ACTH}\) b. CRH c. \(\beta\)-endorphin d. nociceptin e. \(\gamma-\mathrm{MSH}\)

Short answer

Answer: CRH (Corticotropin-releasing hormone)

Step-by-step solution

Understanding the concepts

To solve this exercise, it is important to understand the role of neuropeptides in the immune response and their effects on inflammation. The student needs to know about the HPA axis and the role of each of the given neuropeptides in this context.

Evaluating the alternatives

Let's evaluate each of the given alternatives with respect to their role in inflammation and whether they possess the characteristic mentioned in the question. a. \(\mathrm{ACTH}\) (Adrenocorticotropic hormone) - It is an important hormone that stimulates the production of cortisol, which has anti-inflammatory properties. However, it does not have a proinflammatory action when released by immune cells. b. CRH (Corticotropin-releasing hormone) - It has a key role in activating the HPA axis and is known to exhibit anti-inflammatory properties in this context. Interestingly, CRH also acts as a proinflammatory factor when released locally by immune cells. Therefore, this option seems to satisfy the condition mentioned in the question. c. \(\beta\)-endorphin - It is an endogenous opioid peptide that mainly functions in modulating pain perception and has immunomodulatory properties. However, its role in inflammation is not as clearly described as required by the question. d. Nociceptin - While it is related to pain modulation and the immune response, its specific role in inflammation as described in the question is not clear. e. \(\gamma\)-MSH (Melanocyte-stimulating hormone) - It is involved in various physiological processes, including pigmentation, energy homeostasis, and the immune response. However, it does not have the specific anti-inflammatory and proinflammatory properties mentioned in the question.

Selecting the correct option

Based on the evaluation of each alternative, option b (CRH) is the correct answer as it satisfies the condition mentioned in the question: it has anti-inflammatory properties when activating the HPA axis and proinflammatory properties when released locally by immune cells.