{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Psy137Endocrine System

Reuptake from synaptic cleft into presynaptic neurons

Info iconThis preview shows pages 17–30. Sign up to view the full content.

View Full Document Right Arrow Icon
Reuptake from synaptic cleft into presynaptic neurons Monoamine oxidase (MAO)- enzyme that breaks down monoamines intranueronally 2 isoforms: MAO-A & MAO-B Both forms break down DA, but MAO-B found in dopaminergic terminals buttons Also in blood where it deactivates amines thereby preventing dangerous increases in blood pressure Catechol-O-methyltransferase (COMT)- enzyme that breaks down catecholamines extraneuronally Minor factor in catecholamine deactivation
Background image of page 17

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Major SMT’s Monoamines Dopamine (DA) Norepinephrine (NE) Epinephrine (Epi) Histamine Serotonin or 5- Hydroxytryptamine (5- HT) Quarternary Amine Acetylcholine (Ach) Purines Adenosine ATP Amino Acids Gamma Aminobutyric Acid (GABA) Glycine Glutamate Aspartate
Background image of page 18
Large Molecule (Peptide) Neurotransmitters Peptides are usually broken down from large molecules called polypeptides by specific enzymes Peptides-chains of amino acids linked by peptide bonds The polypeptide are synthesized in the rough ER & then it is broken down into propeptides Propeptides migrate to the Golgi where they are packaged into large dense core vesicles (LDCV) which migrate to the axon hillock LDCV’s are actively transported to the butons bypassing vericosities LMT’s are formed en route in the LDCV’s by endoproteases which break down the propeptide into peptides that will be released Release is frequency modulated in that low firing (low frequency of AP’s) results in no release Above a threshold the more AP’s the more LDCV’s get released No reuptake or recycling, peptides are broken down upon release Broken down by pepsidases (non specific)
Background image of page 19

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Figure 2.25 The preprohormone
Background image of page 20
An Example: Pro-opiomelanocortin (POMC)
Background image of page 21

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
LMT’s Many but the best known Substance P Neurokinin A & B Edogenous opioids Beta endorphin Enkephalin Dynorphin Cholecystokinin (CCK)
Background image of page 22
SMT & LMT Synthesis & Storage
Background image of page 23

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Differences in SMT & LMT Reuptake by presynaptic neuron SMT yes LMT no Release with AP arrival SMT-quantal LMT-frequency modulated Broken down by enzymes SMT-neurotransmitter specific LMT-non-specific pepsidases SMT & LMT are co-localized 2 types of signaling SMT alone SMT + LMT Colocalization Ach with Sub P, Galanin DA with enkephalin, CCK, neurotensin GABA with somatostatin, Motilin, neuropeptide Y NE with enkephalin, vasopressin, galanin 5-HT with enkephalin, sub P, thyrotropin releasing hormone
Background image of page 24
Comparison Diagram comparing classic neurotransmitters (LMT) and Neuropeptides (SMT)
Background image of page 25

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Receptors Types of Receptors Ionotropic Ligand-gated ion channel Metabotropic G-protein coupled receptor (GPCR) Enzymatic Protein kinase or phosphatase Cytosolic Hormone receptors
Background image of page 26
Types of Receptors
Background image of page 27

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Ionotropic Receptors Agoinsts binding opens ion channels Influx of Na+ or Ca++ cause membrane depolarization (EPSP) Efflux of K+ or influx of Cl- cause membrane hyperpolarization (IPSP) Response time between 1-5ms
Background image of page 28
GPCR Agonist binding to receptors causes them to couple to a transducer (G-protein) Affects one or more effectors (enzymes) Catalyze precursors into second messengers Can affect Ion channels Pumps Metabolic activity
Background image of page 29

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 30
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}