**Core Concept**
Endotoxic shock is a life-threatening condition caused by the systemic release of pro-inflammatory cytokines and mediators in response to gram-negative bacterial endotoxins, leading to vasodilation, increased vascular permeability, and ultimately, hypotension and organ dysfunction.

**Why the Correct Answer is Right**
The propagation of endotoxic shock is mediated by the release of cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) from activated macrophages and endothelial cells. These cytokines stimulate the production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) in various tissues, leading to vasodilation and decreased vascular tone. Additionally, the activation of the complement system and the coagulation cascade contributes to the development of organ dysfunction.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not applicable to the propagation of endotoxic shock, as it is not directly related to the pathophysiological mechanisms involved.
* **Option B:** While the hypothalamus is involved in the regulation of the stress response, it is not directly responsible for the propagation of endotoxic shock.
* **Option C:** The release of endothelin-1 (ET-1) can actually contribute to vasoconstriction and hypertension, which is opposite to the vasodilation observed in endotoxic shock.

**Clinical Pearl / High-Yield Fact**
The administration of monoclonal antibodies against TNF-α has been shown to reduce mortality in patients with septic shock, highlighting the importance of cytokine modulation in the treatment of this condition.

**Correct Answer:** C.