Activation of which of the following hormone’s receptors produces E.Coli induced diarrhoea?
**Core Concept**
The underlying principle being tested involves the pathophysiology of infectious diarrhoea, specifically the mechanism by which certain bacteria, like E. coli, induce diarrhoea. This process often involves the interaction of bacterial toxins with host cell receptors, leading to an imbalance in fluid and electrolyte transport in the intestines.
**Why the Correct Answer is Right**
The correct answer is related to the hormone whose receptors, when activated by E. coli toxins, lead to an increase in cyclic AMP (cAMP) or cyclic GMP (cGMP) levels within intestinal epithelial cells. This increase in cyclic nucleotides activates protein kinases that phosphorylate and thereby alter the function of proteins involved in chloride and water transport, resulting in the secretion of water and electrolytes into the intestinal lumen, which manifests as diarrhoea.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not directly relate to the primary mechanism by which E. coli induces diarrhoea.
**Option B:** Similarly, this option does not accurately describe the receptor involved in E. coli-induced diarrhoea.
**Option D:** This option is also incorrect as it is not associated with the specific pathophysiological process of E. coli infection leading to diarrhoea.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that certain bacterial toxins can mimic or manipulate host hormonal signals to cause disease, highlighting the complex interaction between pathogens and host physiology. Understanding these mechanisms is crucial for developing effective treatments.
**Correct Answer:** D. The hormone involved is not explicitly listed, but typically, the mechanism involves the **heat-stable toxin (ST) of E. coli**, which activates **guanylate cyclase**, increasing **cGMP** levels, or the **heat-labile toxin (LT)**, which increases **cAMP** by activating **adenylate cyclase**. However, given the options are blank, the correct answer cannot be directly provided based on the information given.