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PSYCHOBIOLOGY
NEUROTRANSMITTER SYSTEMS IN THE CNS
•Many kinds of neurotrasmitters in the CNS •Synaptic communication: excitatory or inhibitory effects -Glutamate and aspartate (50% of synapses) -GABA ( γ-hidroxibutiric acid, 25 % of synapses) or glycine (spinal cord or lower brainsteam) •Balance between excitation and inhibition
Familia y subfamilia Transmisores y candidates a transmisores
AMINAS. Aminas cuaternarias / monoamines Acetilcolina (Ach)
Catecolaminas
Noradrenalina
Adrenalina
Domapina (DA)
Indolaminas
Serotonina
Melatonina
Aminoácidos GABA: acido aminobutírico
Glutamato
Glicina
Histamina
Neuropéptidos
Péptidos opiáceos
Encefalinas
Met-encefalina
Leu-encefalina
Endorfinas
B-endorfina
Dinorfinas
Dinofina A
Hormonas peptídicas Oxitocina
Sustancia P
Vasopresina
Neuropeptido Y (NPY)
Hormonas liberadoras hipotalámicas
-Neurotransmitters:
DA, 5-HT.. (close synapses) -Neuromodulators: encephalins, opioids (medium distance synapses) -Hormons: ex. testosteron (long distance actuation)
SEPTUM & BASAL NUCLEUS OF MEYNERT
ACETYLCHOLINE, CHOLINERGIC PROJECTIONS
CHOLINERGIC RECEPTORS
•Muscarinic: muscarine ( Amanita muscaria ) •Nicotinic: nicotine (tobacco plant)
BIOGENIC AMINES: MONOAMINES
- Catecholamines: DA, NE and E
- Indolamines: 5-HT
DOPAMINE:
•Both excitatory and inhibitory postsynaptic potentials •Movement, attention, learning, reward (reinforcing effects of drugs of abuse) •DA neurons (brainstem) : sustantia nigra and VTA
ACETYLCHOLINE
•Ach
•Amines
•First NT discovered (CNS and PNS)
•Principal NT secreted by the PNS
•Ganglia of ANS (sympathethic and parasympathethic)
•Facilitatory effects (*sometimes inhibitor)
•Muscular movement (synapsis between neurons and muscular fibers; Somatic NS)
ACETYLCHOLINE PATHWAYS
Three systems: •Dorsolateral PONS: REM sleep (dreams)
- Basal FOREBRAIN [Basal nucleus of Meynert]: activation of cerebral cortex and facilitation of learning
•Medial SEPTUM : modulation of hippocampal functions and role in the formation of memories
- Botulinum toxin (by clostridium botulinum ) prevents the release of Ach-----paralysis, suffocation Botox treatment : stop facial mucle contraction to avoid wrinkles in the skin
- Black widow spider venom stimulates the release of Ach (poison)
AMINOACIDS
•(+): GLUTAMATE and aspartate •(-) : GABA and glicine
•Glu, aspartate and glicine have also a role in many celular functions (GABA is only a neurotransmitter) •Glu and glicina come from glucose as a precursor •Glu is the precursor of GABA •Glu (50 % synapses): memory and neuronal death (Alzheimer’s disease) •GABA (25 % synapses)
NEUROPEPTIDES
OPIOID PEPTIDES
•Endogenous ligands: encephaline, β-endorphin, dynorphin, endomorphins
- Papaver somniferum (opio): morphine
•Semisynthetic opioids: heroine
•Receptors: μ (mu), δ (delta) and κ (kappa) •Analgesia •Sedation, euphoria, respiratory deficits, low pressure, gastrointestinal disorders… •Reward (drugs of abuse, mu receptors) •Dysphoria (kappa receptors)
ENDOCANNABINOIDS
- Endogenous cannabis-like substances •Derived from LIPIDS •Natural ligands: ANADAMIDE & 2-arachidonyl glycerol (2-AG) •THC: Δ-9 tetrahidrocannabinol (marihuana)
•Receptors: CB1 and CB •CB1 distribution: brain , peripheral nerve terminals, heart, testis… •CB2 distribution: immune system and glial cells •Endocrine regulation, ingestive behavior, energetic metabolism, nocioception, reproductory behavior, emotional behavior, learning and memory
•CB1 receptors located in terminal bottoms of glutamatergic, GABAergic, dopaminergic and serotoninergic neurons •Regulation of NT release •Retrograde mechanism (from postsynaptic neurons to the presynaptic neurons !)
•NEUROLEPTICS: D2 receptors
•ANTIDEPRESSANTS: 5-HT, NE
•DRUGS OF ABUSE: DA…
•PARKINSON’S DRUGS: DA
•ALZHEIMER’S DRUGS: NE
PSICOPHARMACOLOGY
•Synthesis •Storage •NT release •Postsynaptic receptors -agonists -antagonists •Inactivation: -reuptake -degradation
