Peptide hormones that induce feelings of fullness or satisfaction help decrease our appetite.
After a meal, a complex network of peripheral peptides suppresses appetite and signal fullness by acting on central targets.
Ingested food passes through the digestive system known as the gastrointestinal tract, also called the GI tract or digestive tract, including the liver, pancreas, and gallbladder. The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. The hollow organs that make up the GI tract are the mouth, esophagus, stomach, small intestine, large intestine, and anus. The liver, pancreas, and gallbladder are the solid organs of the digestive system.
The approximate time of passage for food after intake: mouth to stomach ~10 seconds, food remaining in stomach ~1 to 3 hours, remaining in small intestine for 7 to 9 hours, in cecum, a pouch connected to the junction of the small and large intestines, for 25 to 30 hours, and in the colon for 30 to 120 hours.
The hypothalamus with its arcuate nucleus and its subordinated centers for “satiety,” the paraventricular nucleus, and “hunger,” the lateral hypothalamus, regulates bodyweight.
| The Hypothalamus-Pituitary Complex (wiki commons) | Adult Digestive System (wiki) |
| 
| 
|
Receptors for insulin, glucagon, and adrenaline are involved in ‘signaling with appetite’.
Various gut peptides signal fullness!
Table: Hormones/peptides involved in satiety
| | Hormone | Sequence Information |
| α-MSH | α-Melanocyte-stimulating_hormone | Ac-SYSMEHFRYGKPV-NH2 pdb|1B0Q| A Chain A, PROTEIN (CYCLIC ALPHA MELANOCYTE STIMULATING HORMONE) XCEHXRWCKPVX |
| Amylin | Amylin | KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY-NH2 pdb|8AWT| A Chain A, Islet amyloid polypeptide KCNTATCATQRLANFLVHSGNNFGAILSSTNVGSNTYX pdb|6UCJ| A Chain A, Islet amyloid polypeptide TPIESHQVEK RKCNTATCAT QRLANFLVHS SNNFGAILSS TNVGSNTYGK RNAVEVLKRE PLNYLPLKKK KD |
| Apo A-IV | Apolipoprotein | pdb|1AV1| A Chain A, APOLIPOPROTEIN A-I MLKLLDNWDS VTSTFSKLRE QLGPVTQEFW DNLEKETEGL RQEMSKDLEE VKAKVQPYLD DFQKKWQEEM ELYRQKVEPL RAELQEGARQ KLHELQEKLS PLGEEMRDRA RAHVDALRTH LAPYSDELRQ RLAARLEALK ENGGARLAEY HAKATEHLST LSEKAKPALE DLRQGLLPVL ESFKVSFLSA LEEYTKKLNT Q |
| BNRP | Bombesin/bombesin related peptides Bombesin | Pyr-QRLGNQWAVGHLM-NH2 pdb|2N0B| A Chain A, Neuromedin C (NMC) GNHWAVGHLMX pdb|7W3Z| L Chain L, Gastrin Releasing Peptide PRGNHWAVGHLM-NH2 PRGNHWAVGHLMX |
| Calcitonin-gene-related peptide | Calcitonin | pdb|7TYO| P Chain P, Calcitonin CGNLSTCMLGTYTQDFNKFHTFPQTAIGVGAPX pdb|7TYH| P Chain P, Calcitonin CGNLSTCMLGTYTQDFNKFHTFPQTAIGVGAPX |
| CART | Cocaine and amphetamine regulated transcript | pdb|1HY9| A Chain A, COCAINE AND AMPHETAMINE REGULATED TRANSCRIPT PROTEIN YGQVPMCDAGEQCAVRKGARIGKLCDCPRGTSCNSFLLKCL |
| CCK | Cholecystokinin | pdb|1D6G| B Chain B, cholecystokinin-8 DYMGWMDFX |
| CRF | Corticotropin-releasing_hormone, Corticotropin-releasing factor | pdb|1GO9| A Chain A, CORTICOTROPIN RELEASING HORMONE SEEPPISLDLTXHLXREVLEMARAEQLAQQAHSNRKLMEIIX pdb|6P9X| P Chain P, Corticoliberin SEEPPISLDLTFHLLREVLEMARAEQLAQQAHSNRKLMEII NP_000747.1 corticotropin-releasing hormone preproprotein [Homo sapiens] MRLPLLVSAG VLLVALLPCP PCRALLSRGP VPGARQAPQH PQPLDFFQPP PQSEQPQQPQ ARPVLLRMGE EYFLRLGNLN KSPAAPLSPA SSLLAGGSGS RPSPEQATAN FFRVLLQQLL LPRRSLDSPA ALAERGARNA LGGHQEAPER ERRSEEPPIS LDLTFHLLRE VLEMARAEQL AQQAHSNRKL MEIIGK |
| Enterostatin | Enterostatin | VPDPR |
| GLP-1 | Glucagon-like_peptide-1 Keywords=glucagon Glucagon-is-a-glucose-releasing-hormone | HSQGTFTSDYSKYLDSRRAQDFVQWLMNT pdb|3IOL| B Chain B, Glucagon HAEGTFTSDVSSYLEGQAAKEFIAWLVKGRG |
| Leptin (protein); | Leptin, Keywords=Leptin | pdb|8AVF| A Chain A, Leptin AHHHHHHPGG PGSENLYFQG GSTGGVPIQK VQDDTKTLIK TIVTRINDIS HTQSVSSKQK VTGLDFIPGL HPILTLSKMD QTLAVYQQIL TSMPSRNVIQ ISNDLENLRD LLHVLAFSKS CHLPWASGLE TLDSLGGVLE ASGYSTEVVA LSRLQGSLQD MLWQLDLSPGC |
| OXM | Oxyntomodulin | pdb|9N0E| P Chain P, Oxyntomodulin HSQGTFTSDYSKYLDSRRAQDFVQWLMNTKRNRNNIA |
| POMC | Proopiomelanocortin drugbank/DBCAT001333 The human pro-opiomelanocortin (POMC) is differently processed in different tissues. | BES79389.1 pro-opiomelanocortin [Homo sapiens] MPRSCCSRSG ALLLALLLQA SMEVRGWCLE SSQCQDLTTE SNLLECIRAC KPDLSAETPM FPGNGDEQPL TENPRKYVMG HFRWDRFGRR NSSSSGSSGA GQKREDVSAG EDCGPLPEGG PEPRSDGAKP GPREGKRSYS MEHFRWGKPV GKKRRPVKVY PNGAEDESAE AFPLEFKREL TGQRLREGDG PDGPADDGAG AQADLEHSLL VAAEKKDEGP YRMEHFRWGS PPKDKRYGGF MTSEKSQTPL VTLFKNAIIK NAYKKGE pdb|8W8W| L Chain L, alpha-MSH SYSMEHFRWGKPV |
| PP | Pancreatic_polypeptide | pdb|1TZ5| A Chain A, Pancreatic prohormone, neuropeptide Y, Pancreatic prohormone APLEPVYPGDNATPEQMARYYSALRRYINMLTRPRYX |
| PYY | Peptide YY | AAA36433.1 peptide YY [Homo sapiens] MVFVRRPWPA LTTVLLALLV CLGALVDAYP IKPEAPGEDA SPEELNRYYA SLRHYLNLVT RQRYGKRDGP DTLLSKTFFP DGEDRPVRSR SEGPDLW pdb|2DEZ| A Chain A, Peptide YY YPIKPEAPGEDASPEELNRYYASLRHYLNLVTRQRYX |
| Serotonin | Serotonin | |
| Somatostatin | Somatostatin | KAI4033008.1 somatostatin [Homo sapiens] MLSCRLQCAL AALSIVLALG CVTGAPSDPR LRQFLQKSLA AAAGKQELAK YFLAELLSEP NQTENDALEP EDLSQAAEQD EMRLELQRSA NSNPAMAPRE RKAGCKNFFW KTFTSC pdb|2MI1| A Chain A, Somatostatin-14 AGCKNFFWKTFTSC |
| Thyrotropin-releasing hormone | Thyrotropin-releasing_hormone | Pyr-HP-NH2 NP_009048.1 thyrotropin releasing hormone preproprotein [Homo sapiens] MPGPWLLLAL ALTLNLTGVP GGRAQPEAAQ QEAVTAAEHP GLDDFLRQVE RLLFLRENIQ RLQGDQGEHS ASQIFQSDWL SKRQHPGKRE EEEEEGVEEE EEEEGGAVGP HKRQHPGRRE DEASWSVDVT QHKRQHPGRR SPWLAYAVPK RQHPGRRLAD PKAQRSWEEE EEEEEREEDL MPEKRQHPGK RALGGPCGPQ GAYGQAGLLL GLLDDLSRSQ GAEEKRQHPG RRAAWVREPL EE |
| Urocortins | Urocortin | pdb|2RMF| A Chain A, Urocortin DNPSLSIDLT FHLLRTLLEL ARTQSQRERA EQNRIIFDSV |
Reference
Huda MS, Wilding JP, Pinkney JH. Gut peptides and the regulation of appetite. Obes Rev. 2006 May;7(2):163-82. [wiley]