Answer:
the number of oxytocin receptors on the cell surface
Step-by-step explanation:
The increase of the number of hormone receptors present on the surface of target cells increases the sensitivity of such cells to the hormone. Oxytocin is a neuropeptide hormone produced by the hypothalamus and released by the posterior pituitary gland. This hormone acts as a neurotransmitter that binds to oxytocin receptors in order to trigger a molecular cascade that finalizes with the activation of the enzyme Phospholipase-C. Oxytocin receptors are found in different types of brain cells including, for example, the amygdala and hippocampus (where oxytocin binds). This hormone acts as a chemical messenger that modulates brain functions associated with the reproductive system (i.e., childbirth and lactation) and human behavior.