IPHY 4440 1st Edition Lecture 14Outline of Last Lecture Feedback loopsOutline of Current Lecture II. Nonapeptide hormones III. Chemical structureIV. Functions of nonapeptidesV. Nonapeptides and behaviorVI. Other behavioral effectsVII. Pineal glandVIII. Melatonin SynthesisIX. Pineal gland functionsX. ReproductionXI. Adv. Of melatonin (melatonin therapyCurrent LectureI. Nonapeptide hormones A. Chemistry of nonapeptides1. Oxytocin-like + smooth muscle2. Vasopressin-like antidiuretic Not going to be the same exact as OXY and vasopressin but the structure and activity will be LIKE it Oxytocin like peptide: simulate contraction of smooth muscles Vasopressin: to inhibit the excretion of water by promoting the retention of water in your body B. OXY: neutral peptide (If charged will disrupt the smooth muscle), will increase reproductive smooth muscle contraction- Prohormone: prooxyphysinC. Pressins: basic peptides (ARG or LYS) (Positive charge because basic peptides, ability/presence to bind to their receptors), increase vascular smooth muscle contraction and raise blood pressureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. -Raise blood pressure is a pharmacological: only when vasopressin in blood concentration becomes really high in the blood but only during unusual circumstances such as getting your arm cut off so need to constrict blood vessels in order to keep that blood pressure goingBut physiologically not a normal circumstance bcdoesn’t do that under normal circumstances - pressins: anti-diuretic: water reabsorption physiological - prohormone: propressophysinII. Chemical structureA. Oxytocin: 2 cysteines= Cystine- Amino acid 1) 2) 3) 4) 5) and so on1) and 6) and cysteinescome together to form a cystine and has a tail of 3 amino acids3) and 8) is a neutral aa: makes oxytocin a neutral peptide Aa 3) isotocine to have tocin- like activity This is a sequence of oxytocin B. Arginine vasopressin: basic AA at 8 essential for activity 9 amino acidsDisulfide bond and tail8) Is Arg basic amino acid, in order to have a pressin activity the aa #8 needs tobea basic acid or ArgPhe 3) enhances the activity of arg in position number 8 Arg is not the only vasopressin in mammalsIf sub aa 8 with lysine instead of Arg it will work because is a basic aa (pigs and hippos have lysine)C. Lysine vasopressin: Phe at (3) and Lys at (8)III. Functions of nonapeptidesA. Oxytocin1) Increase reproductive smooth muscle for birth, ejaculation, and orgasm 2) Increase milk letdown by myoepithelial cells of mammary gland (Ducts containing milk, have myoepithelial cells are part muscle/part epithelial, squeeze milk out)B. Vasopressin1) increase water reabsorption= antidiuretic hormone that opens water channels called aquaporins2) AVP action in nephron and collecting duct: Responsible for taking back water in kidney filtrate 2 waysTake some water out of filtrate (top lighter part) and back into the bottomVasopressin binds to receptor first stimulates phosphorylation of aquaporin, then go to membrane to suck up water, insert themselves in membrane to letwater in Vasopressin canstim transcription of aquaporin * Alcohol inhibits AVP Decreases AVP so cannot contain urine which leads to a big dehydration headache IV. Nonapeptides and behaviorPrairie Vole, Microtusochrogaster are monogamous - NT and NM go to parts of brain that control emotion, cognition, trust, bonding2 prairie good examples: monogamous form life long bonds which is unusual for rodents - If go out to trap these creatures; Find that the majority of them are monogamous pairs; The meadow voles: closely related cousins, not monogamous - Distribution of OXY Receptors: Monogamous Prairie vole vs. Nonmonagomous Meadow vole: Localized in differentparts of brain (OXY is the key to their monogamous behavior OXY signal diff in both species)V. Other behavioral effectsA. Oxytocin: Lordosis in rats, mice hamstersEwes to nurture young(Introduction to maternal behavior)C. Vasopressin: increase in paternal behavior and increase in aggression toward strange males Key note: The behavioral effects of OXY and AVP are due to their roles as neurotransmitters or neuromodulators, NOT as neurohormones!VI. Pineal gland (Not part of HP axes but still important role)A. Anatomy: Forebrain: = telencephalon + diencephalon (posterior part)B. Diencephalon: Center (thalamus), floor (hypothalamus, roof (epithalamus) pineal C. Pineal= epiphysis: secretes melatonin during dark-Pinealocytes: endocrine cells that make melatonin, Supporting cells not making hormones: neuroglial cellD. photophase= lightE. Scotophase= darkXII. Melatonin SynthesisBegins with an amino acid tryptophan 5-hydroxytryptophan serotonin (NAT=enzyme)N-acetylserotonin (HIOMT=enzyme) melatonin * Melatonin is a biogenic amine so starts with an amino acid tryptophan Serotonin is a biogenic amine so enzyme converting amino acid into a biogenic amine= decarboxylase (get rid of acid part) in between 5-hydroxy and serotonin Rate-limiting enzyme: NAT because has to go up, increased during dark phaseNOT HIOMT: always enough floating around during synthesis VII. Pineal Functions1) Endogenous rhythms (SCN): Mammal cerebral hemisphere covers pineal gland2) Mammal pineal lost photoreceptor structure*Master clock that dictates our 24 hours circadian cycle : SCN cant get rid of it because always running/cranking will tell you when it thinks its light/dark, hungry/not hungryMelatonin acts in concert with SCN: helps keep our endogenous rhythm on track Pineal gland cannot pick up lights bc lost photoreceptor so need to pick it up elsewhere.. Our eyes 3) light decrease sympathetic activation decrease NE decrease melatonin secretion4) darkness increase sympathetic activation increase NE increase melatoninsecretion - Darkness to retina: receives signal of darkness; Pathway in which electrical signals travel: RHT; Then goes to the spinal chord to ganglion - Part of sympathetic pathway/autonomic (spinal chord, preganglionic) Light/dark cycle coming out of sympathetic so the neurotransmitter that comes out of SCG must be norepinephrine travels back to brain to reach pineal gland stimulates it and releases melatonin VIII. Reproductiona) Puberty onset: indirect evidence in humans suggest it is anti-pubertyb) Seasonal Breeding: Anti-reproductive in
View Full Document