Messengers hormone-like

Peptide-hormones like hypothalamus-pituitary, gastrointestinal, parathyroid, neurohormones, Gfs related peptide-hormones cannot penetrate the plasma membrane and their receptors are located on the cell surface and the signal transport to the nucleus is becoming via a second messenger. The main hormone action seems to be DNA synthesis whereas other including mediation of neurotransmission, enzyme synthesis, regulation and synthesis of structural proteins are responsible for the specific characteristics of differentiated cell. 

Zoeller RT, Dowling ALS, Vas AA. 2000. Developmental exposure to polychlorinated biphenyls exerts thyroid hormone-like effects on the expression of RC3/neurogranin and myelin basic protein messenger ribonucleic acids in the developing rat brain. Endocrinology 141(1) 181-189. 

Steroid hormones like testosterone, progesterone, cortisol, aldosterone, and estradiol are important endocrine chemical messengers that are involved in a vast number of physiological processes including metabolism, inflammation, electrolyte and fluid balance, and secondary sex differentiation (Foster, 2004 Ghayee and Auchus, 2007 Newton and Holden, 2007 Williams-Ashman and... 

A hormone, like a neurotransmitter, is a chemical messenger that carries signals from one cell to another. The difference is neurotransmitters stick close to home, moving in a highly directed way from... 

Not released from glands chemicals acting more quickly than hormones, but like them consequentially. Sometimes all the above set of messenger molecules are described under the endocrine system. Some are released by the peripheral sense receptors. There are many other possible hormones such as glucose and several of the simplest hormones are related to bacterial sensors e.g. NO and some ions (see Chapter 6). 

Catecholamines produced in the brain and in other neural tissues function as neurotransmitters, but epinephrine and norepinephrine are also hormones, synthesized and secreted by the adrenal glands. Like the peptide hormones, catecholamines are highly concentrated within secretory vesicles and released by exocytosis, and they act through surface receptors to generate intracellular second messengers. They mediate a wide variety of physiological responses to acute stress (see Table 23-6). 

Part 1 concludes with a discussion of the actions of insulin. This provides an opportunity to see how regulatory mechanisms, such as phosphorylation dephosphorylation and control by second messengers, enable the body to respond to a hormone which, in many ways, behaves like a growth factor. 

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