NEUROPEPTIDE Y AND NEUROTENSIN
Neuropeptide-Y is a 36 aminoacid peptide found in high concentration in brain and in sympathetic neurons it causes hypotension increased feeding respiratory depression vasoconstriction of cerebral blood vessels positive inotropic and chronotropic actions on the heart
Neurotensin is a tridecapeptide found in circulation and in gastrointestinal tract it causes vasodilatation hypotension hyperglycemia inhibition of gastric acid secretion and inhibition of gastric motility it also causes hypothermia analgesia and secretion of many hormones
EICOSANOIDS: PROSTAGLANDINS
These are the most prevalent autacoids found in almost every tissue as well as body fluids they are produced in response to astonishingly diverse stimuli in minute quantities and produce a remarkably broad spectrum of effects that embrace practically every biological function prostaglandins have been named so because they were first isolated form the semen of the sheep and that of human prostate gland
chemically they are 20-carbon unsaturated fatty acids containing 5 carbon cyclopentane ring there are number of different prostaglandins and are named as A B C D E F etc depending on the constituent of cyclopentane ring Each type of prostaglandin if possess one double bond in the hydrocarbon chain they are again classified as PG E1 or A1 if there are two double bonds they are classified as PG E2 OR A 2OR B2 and so on similarly they may be PG E3 or PG F3 etc
ALL prostaglandine are synthesized from essential esterified fatty acids these get activated to form arachidonic acid this is the rate limiting step from arachidonic acid different prostaglandins are synthesized with the help of enzyme prostaglandin synthetase
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