Metabolic Effects of Hormones ط Communication among cells and tissues

1. Metabolic Effects of Hormones • ط     Communication among cells and tissues • ط     Classifications of hormones and Eicosanoids • ط     Mechanisms of hormone action  • Hormonal Regulation of fuel metabolism • Physiological and Metabolic Effects of Hormones • Insulin / Glucagon • Epinephrine / Cortisol • ط      Signal transducing receptors •                                            L5 761 -8 

2. Hormones-Receptors • Every process is regulated by one hormone or more: bld pressure, elect. balance, digestion … • Coordination of Metab. is achived by the neuroendocrine system • fig 23.1, Cell sense change => RESPOND => secret messenger => BIND to Receptor => trigger change • All hormones act through specific (selective) receptors bind with high-affinity • Each cell has its own hormone receptors => define responsiveness • 2 different cells with the same type of receptors => may have different hormone action • fig23.4, H-R Binding is divided to (fast-extracellular, cytosolic, nuclear-slow) => Response • The high affinity of receptors allow response to very low conc of hormones

5. Types of Receptors • Ion Channel: change in potential => result in open/shut gate • Enzyme: extracellualr activated by hormones • 2nd Messnger: generated in cell (e.g. cAMP) • No Intrinsic Enz activity: recruits PK in cytosol => passes the signal • Adhesion: on cell surface => interact with mol. In extracellular matrix => • send signal to cytoskeleton • 6.Nuclear: steroid => changes level of expression of one gene or more

6. Chemical Diversity • 1. fig23.4, Table23.1, Several classes distinguished by their chemical structure and mode of action: • Act from surface of cells • Peptides (e.g. INS / Glc) – drived from AAs => Rapid • Amines (e.g. epinephrine, cAMP / Glycogen) – drived from tyrosin & tryptophan • Eicosanoids (e.g. prostaglandine) – 20 carbon polyunsaturated essential FA • Enter the nucleus to act • Steroids (e.g. cortisol, sex hormones) synth from cholesterol • Vit D (e.g. calcitriol) synth from Vit D • Retinoid (e.g. Retinol), synth from Vit A • Thyroid (e.g. T4, T3) synth from thyroglobulin • Steroids (e.g. cortisol), vit D, retinoid, thyroid hormones • Enters the cell and activates cytosolic guanyl cyclase • Nitric oxide (NO) – free radical, synth from Arginine (N2) + O2

7. Chemical Diversity 2.  classification by the way the get from point of release to target cell: Endocrines (e.g. insulin): 2 pionts, secreted hormone (gland) far from target cell and reach through blood Paracrine (e.g. eiconoids): 2 points, secreted hormone reach target cell through extracellular space or canal Autocrine (e.g. ): hormone is secreted by the target cell

8. Regulation of Fuel Metabolism The requirement of min by min adjustment of bld glc near 4.5mM involves combined action of INS, Glg, Epinephrine and cortisol on tissues (liver, muscle, AT) 1. INS (reduces bld glc): signal tissues to uptake bld glc & storage as glycogen & TG fig23.26, Table23.3 2. Glg (increases bld glc/cAMP): signals tissue to produce glc by inhibiting glycolysis & activation of glycogenolysis (in liver) and gluconeogenesis fig23.27, Table23.4

9. Regulation of Fuel Metabolism The requirement of min by min adjustment of bld glc near 4.5mM involves combined action of INS, Glg, Epinephrine and cortisol on tissues (liver, muscle, AT) 3. Epinephrine (fast stress increase fuel/cAMP): neuronal signal (in brain) trigger release leading to O2 uptake (by lung), increase heart beat, raise bld pressure, promoting of O2 and fuels to tissues (muscle) Table23.6 Activates Glycolysis, glycogenolysis and TG lipase 4. Cortisol (long-term stress/change enz amount not regulation): neuronal signal (in barin) triggers release leads to release of stored TH (in AT), stimulates proteolysis (in muscle), stimulating gluconeogenesis, glycogenolysis and TG lipase