What is the effect of dopamine in the tuberoinfundibular pathway?

The correct answer reflects the role of dopamine in the tuberoinfundibular pathway, which is responsible for regulating the secretion of prolactin from the anterior pituitary gland. Dopamine acts as an inhibitory neurotransmitter in this pathway, thus preventing the release of prolactin. When dopamine is released from the hypothalamus into the pituitary gland, it binds to dopamine receptors on lactotroph cells, leading to a decrease in prolactin secretion. This is one of the key functions of dopamine in maintaining hormonal balance in the body, as prolactin is involved in various physiological processes, including lactation and reproductive functions.

In contrast, the other choices represent different functions or pathways that are not related to the specific role of dopamine in the tuberoinfundibular pathway. For example, stimulating appetite is more closely associated with other neuropeptides and signaling pathways, enhancing memory formation typically involves different neurotransmitters such as glutamate, and regulating heart rate is primarily under the control of the autonomic nervous system, notably by norepinephrine and acetylcholine rather than dopamine in this context.