Are hypothalamic hormones central neurotransmitters?
Chemical neutotransmitters share a number of properties. They are found in, synthesised by, and released from neurons. When they are released from nerves, they have specific, drug sensitive effects on target cells; and these effects are also seen when they are applied to target cells exogenously. Finally, neurotransmitters are rapidly metabolised or removed from the synaptic cleft so that their actions are brief. ‘Hypothalamic hormones’ (releasing hormones and release inhibiting hormones) have not traditionally been thought of as neurotransmitters. Although it is true that these hormones are released from nerves into the portal vessels to act on cells of the anterior and intermediate lobes of the pituitary, it is unlikely that their only sites of action are in the pituitary. Data suggesting that the hypothalamic hormones function as chemical neurotransmitters are reviewed below.
KeywordsThyrotropin releaSing Hormone Median Eminence Luteinising Hormone releaSing Hormone Luteinising Hormone releaSing Hormone Posterior Hypothalamus
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