Neuromodulator

A neuromodulator is a substance other than a neurotransmitter, released by a neuron at a synapse and conveying information to a region of neurons, either enhancing or dampening their activities. In contrast, neurotransmitters only convey information between two neurons.

A neuromodulator is a relatively new concept in the field and it can be conceptualized as a neurotransmitter that is not reabsorbed by the pre-synaptic neuron or broken down into a metabolite. Such neuromodulators end up spending a significant amount of time in the CSF (cerebrospinal fluid) and influencing (or modulating) the overall activity level of the brain. For this reason, some neurotransmitters are also considered as neuromodulators. Examples of neuromodulators in this category are serotonin and acetylcholine.

Types

 * Opioid peptides - these substances block nerve impulse generation in the secondary afferent pain neurons. These peptides are called opioid peptides because they have opium-like activity. The types of opioid peptides are:
 * Endorphins
 * Enkephalins
 * Dynorphins
 * Substance P
 * Octopamine