synthesized by the liver, recycled in the brain - easily crosses BBB
binds to post-synaptic receptors:
nicotinic receptors - excitatory response
muscarinic receptors - inhibitory response
Implicated in Huntington's disease - degeneration of Striatum
important in sleep/arousal (RAS) - cortical activation, REM sleep
hippocampus - implicated in Alzhiemer's disease
projections to "neocortex", hippocampus, olefactory bulb, cingulate
widely distributed, originates in raphe nuclei (brainstem)
is believed to play an important role in (the inhibition of) anger, aggression, body temperature, mood, sleep, vomiting, sexuality, and appetite
project to cerebellum, medulla, limbic system
primarilly from the locus ceruleus (Latin for 'the blue spot')
synthesized from dopamine, released from the adrenal medulla into the blood as a hormone, and as a neurotransmitter in the central nervous system and sympathetic nervous system where it is released from noradrenergic neurons. The actions of norepinephrine are carried out via the binding to adrenergic receptors.
important in mood regulation, arousal, attemtion (maintaining, focusing), memory, processing speed
pathways project to forebrain, cerebellum, spinal cord
functions as a neurotransmitter, activating five types of dopamine receptors
produced in several areas of the brain, including the substantia nigra
important roles in behavior and cognition, motor activity, motivation and reward, regulation of milk production, sleep, mood, attention, and learning.
Via the dopamine receptors D1, D2, D3, D4 and D5, dopamine acts as both an excitatory and inhibitory neurotransmitter
mesocortical pathway projects the frontal lobes (cognitive funcitoning, motivation, and emotional control)
mesolimbic projects to the midbrain then to the nucleus accumbens, which is located in the striatum and is a part of the limbic system (reward, pleasure)
nigrostriatal pathway connects the substantia nigra with the striatum... is particularly involved in the production of movement, as part of a system called the basal ganglia motor loop.
The pigment in the substantia nigra is dark (arrows) because of the presence of brown neuromelanin in neurons
GABA - quite common, 1/3 of all synapses receptive to GABA, inhibitory