Locus coeruleus neurons in culture have a developmentally transient alpha 1 adrenergic response

Intracellular recordings from locus coeruleus neurons grown in explant cultures reveal age-related differences in the responses to iontophoretically applied noradrenaline. Cells grown in culture for more than 26 days exhibit a simple hyperpolarizing response while cells cultured for less than 26 days often have biphasic hyperpolarizing-depolarizing responses. Pharmacological studies with selective adrenergic agonists and antagonists show that the hyperpolarizations and hyperpolarizing parts of biphasic responses are mediated by alpha 2 adrenergic receptors while the depolarizing responses are mediated by alpha 1 receptors. These observations may reflect a population of neurotransmitter receptors which is transiently present during early postnatal development.