Pharm Intro Flashcards
Where do 5HT neurons from rostral raphe project to?
Ascend to cerebral cortex, limbic regions, and basal ganglia
Where do 5HT neurons from caudal raphe project to?
Terminate in medulla or descend to spinal cord
What receptors does 5HT act on?
Both ion channels and G proteins. May be excitatory or inhibitory.
What does 5HT do to blood vessels?
Vasoconstriction
How does LSD affect 5HT?
Antagonizes. Structure is similar.
4 major DA pathways
- Substantia nigra to caudate/putamen
- Ventral tegmentum to mesolimbic forebrain
- Ventral tegmentum to frontal cortex
- Tuberoinfundibular system (arcuate nucleus to median eminence)
What types of receptors does DA act on?
DA acts via 5 different G proteins
D1 and D5 activate adenylyl cyclase. D2-4 inhibit adenylyl cyclase.
How does DA effect prolactin secretion?
Inhibits prolactin secretion?
2 main NE pathways
- Axons from locus coeruleus project to frontal cortex, thalamus, hypothalamus, limbic system, and cerebellum.
- NE axons from caudal raphe nuclei ascend to amygdala and midbrain.
NE receptors
NE acts via G protein coupled adrenergic receptors. A1 and B1 are excitatory. A2 and B2 are inhibitory.
From where is histamine released?
Characteristic of neurons
Function
3 different receptor subtypes
- Histamine pathways originate in the tuberomamillary nucleus.
- Neurons are pacemakers.
- Aids in arousal, analgesia, locomotion, learning, and memory.
- 3 different receptor subtypes.
- H1 acts via Gq, excitatory
- H2 acts via Gs, usually excitatory
- H3 autoreceptors aid in negative feedback, inhibiting histamine synthesis / release.
Mechanism of antihistamines
Inverse agonist
3 main glutamate pathways
- Cortico-cortical pathways
- Between thalamus and cortex
- Extrapyramidal pathway (b/w cortex and striatum)
Glutamate receptors
Acts via ion channels (NMDA, KA, AMPA) and G proteins (mGLU1-8)
GABA receptors
- Acts via ion channels (GABAa) and G proteins (GABAb).
- Drugs effect GABAa more than GABAb.
- GABAa receptor is a Cl channel (hyperpolarizing). 2 binding sites for GABA. Pentameric. Benzos and barbiturates bind to GABA receptors to inhibit seizures.
Function of glycine
Inhibitory NT acting via interneurons of SC and brain stem. Cl ion channel.
Synthesis / breakdown of GABA
- Glutamic acid decarboxylase converts glutamate to GABA, and vice versa.
- GABA transaminase breaks GABA down to succinic semialdehyde. Blocking this enzyme increases GABA levels.
3 groups of Ach neurons
- Basal forebrain cholinergic complex
- Pontomesencephalotegmental cholinergic complex
- Ach is also released from interneurons in the striatum.
Ach receptors
- Ach acts on G protein coupled M1 and M2 muscarinic receptors.
- M1 receptors are excitatory via ↓ K+ conductance, ↑ IP3 and DAG production
- M2 receptors are inhibitory via ↑ K+ conductance, ↓ cAMP production
- Brain also contains excitatory nicotinic receptors.
Peptide hormones •Cholecystokinin •Neuropeptide Y •Orexin •Hypothalamic and pituitary hormones •Opioids •Substance P
- Cholecystokinin: satiety
- Neuropeptide Y: stimulates feeding behavior
- Orexin: stimulates feeding behavior and wakefulness
- Hypothalamic and pituitary hormones: oxytocin and vasopressin (ADH)
- Opioids (endorphins, enkephalins, dynorphin): pain perception
- Substance P: pain perception
