Hypothalamic neurons are localized exclusively in certain hypothalamic areas of the brain and when deteriorated causes a condition known as narcolepsy. Which of the following are considered hypothalamic neurons and is involved in the development/state of narcolepsy?

A. Orexin/Hypocretin: Orexin (also called hypocretin) neurons are localized in the lateral hypothalamus and play a critical role in maintaining wakefulness. Loss or degeneration of these neurons is strongly associated with narcolepsy, leading to excessive daytime sleepiness and sudden sleep attacks. B. Glutamate/Glycine: Glutamate and glycine are widespread excitatory and inhibitory neurotransmitters in the CNS, respectively. While they participate in general neuronal signaling, they are not specific hypothalamic neurons implicated in narcolepsy. C. Dopamine/Serotonin: Dopamine and serotonin are monoamine neurotransmitters involved in mood, reward, and sleep-wake regulation but are not exclusive to the hypothalamus and are not the primary cause of narcolepsy. D. Intraneuronal/Histamine: Histamine neurons in the hypothalamus contribute to arousal and wakefulness but are not the neurons specifically lost in narcolepsy. They modulate sleep-wake cycles but do not account for the disorder’s pathophysiology.