Which of the following is NOT a category of neurotransmitters?

The correct answer is that sugars are not classified as a category of neurotransmitters. Neurotransmitters are primarily chemical messengers that transmit signals across a synapse from one neuron to another and can be broadly categorized into specific groups based on their chemical structure and function.

Amino acids, for instance, are the building blocks of proteins and also serve as neurotransmitters (like glutamate and glycine) that play crucial roles in excitatory and inhibitory signaling in the nervous system. Amines, such as dopamine, serotonin, and norepinephrine, are derived from amino acids and are involved in various functions including mood regulation and motor control. Peptides consist of short chains of amino acids and include neurotransmitters like endorphins, which can modulate pain perception and emotional responses.

While sugars are essential nutrients and can influence energy metabolism and cellular functions, they do not serve as neurotransmitters and thus do not fit into the recognized categories such as amino acids, amines, and peptides.