Which of the following hormones does not exhibit the mechanism of action by its interaction with membrane bound receptors?

Options

A. Catecholamines
B. Peptide
C. Potypeptide
D. lodothyronines

Answer

To determine which hormone does not exhibit the mechanism of action by interacting with membrane-bound receptors, we need to analyze the options provided: catecholamines, peptides, polypeptides, and iodothyronines.

### Step-by-Step Solution:

1. **Understanding Hormone Mechanisms**: Hormones can act through two primary mechanisms:
- **Membrane-bound receptors**: Typically for lipid-insoluble hormones that cannot cross the cell membrane.
- **Intracellular receptors**: Typically for lipid-soluble hormones that can cross the cell membrane.

2. **Analyzing Catecholamines**:
- Catecholamines (like epinephrine and norepinephrine) are derived from amino acids and are considered lipid-insoluble hormones.
- They act via membrane-bound receptors.
- **Conclusion**: Catecholamines do not fit the criteria of the question.

3. **Analyzing Peptides**:
- Peptide hormones are also lipid-insoluble and act via membrane-bound receptors.
- **Conclusion**: Peptides do not fit the criteria of the question.

4. **Analyzing Polypeptides**:
- Polypeptide hormones, similar to peptides, are lipid-insoluble and act via membrane-bound receptors.
- **Conclusion**: Polypeptides do not fit the criteria of the question.

5. **Analyzing Iodothyronines**:
- Iodothyronines (thyroid hormones like thyroxine) are unique. Although they are derived from amino acids and contain iodine, they are lipid-soluble.
- They can cross the cell membrane and act via intracellular receptors rather than membrane-bound receptors.
- **Conclusion**: Iodothyronines do not act via membrane-bound receptors.

### Final Answer:
The hormone that does not exhibit the mechanism of action by its interaction with membrane-bound receptors is **Iodothyronines**.

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