Ch 5 Hormones - Endocrine vs neurocrine function At a...

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Endocrine vs. neurocrine function At a typical synapse, the presynaptic neuron releases neurotransmitter onto one target cell. An endocrine cell releases its hormone into the blood stream.
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The one to many nature of endocrine communication
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Protein hormones
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Some protein hormones
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Amine and Steroid hormones Epinephrine (adrenaline) Norepinephrine (NE) Thyroid hormones Melatonin Gonadal: Estrogens (e.g., estradiol) Progestin (e.g., progesterone) Androgens (e.g., testosterone Adrenal Glucocorticoids (e.g., cortisol) Mineralocorticoids (e.g., aldosterone)
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Receptors on the plasma membrane Protein/peptides Most amine hormone Epinephrine Norepinephrine Melatonin These receptors generally involve a second messenger system with cyclic AMP (cAMP) or cyclic GMP (cGMP).
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Receptors in the cytoplasm Steroid hormones: Gonadol Estrogens Progestins Androgens Adrenal Glucocorticoids Mineralocorticoids Also, one amine hormone: Thyroid hormone When the cytoplasmic receptor binds hormone, it moves into the nucleus, where it affects gene expression.
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Not so simple Therefore, steroid hormones act slowly. Also, when steroid-receptor complexes form they alter gene expression and subsequently protein production, producing long-lasting effects. Some steroids act on more than one receptor – called receptor isoforms – with functional differences. And, steroid receptor cofactors may be necessary for the cell to respond to the steroid- receptor complexes in cell-specific ways. For example, steroid receptor cofactor-1 (SRC-1) and CREB-binding protein (CBP) play a role in sexual dimorphism in the brain. And, steroids can also have a nongenomic effect – a rapid, brief effect involving neuronal membrane receptors! Likewise, allosteric modulation occurs when steroids interact with receptors for other molecules; for instance, the endogenous transmitter for the benzodiazapine binding site on GABA receptors may be alloprenanolone, classified as a neurosteroid because it is produced in the brain
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  • Fall '07
  • shaine
  • anterior pituitary gland

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