SOMATOSTATIN IN MUCOSA OF STOMACH AND DUODENUM IN GASTRODUODENAL DISEASE

Transcription

1 /78/ $02.00/0 GASTROENTEROLOGY 75: Cpyright 1978 by the American Gastrenterlgical Assciatin Vl. 75 N.1 Printed in U.S A. SOMATOSTATN N MUCOSA OF STOMACH AND DUODENUM N GASTRODUODENAL DSEASE J. A. P. CHAYVALLE M.D. F. DESCOS M.D. C. BERNARD B.Sc. A. MARTN M.D. C. BARBE M.D. AND C. PARTENSKY M.D. NSERM U 45 and Centre d'endscpie Digestive Pavilln H Bis and Service de Chirurgie Pavilln 0 Hpital Eduard Herrit Lyn France n rder t study the distributin f smatstatin in the upper digestive tract in man bipsies were taken thrugh endscpy r at surgery frm the fundus antrum and dudenal bulb in 15 subjects with n gastrdudenal lesin 12 patients with severe antral and/r fundic atrphy in the sampling area 28 patients with an active dudenal ulcer and 14 patients with a nnmalignant gastric ulcer. The specimens were extracted in 2 N acetic acid and tested fr smatstatin cntent with a specific radiimmunassay. n the cntrl subjects the smatstatin cncentratin (nangrams per milligram f wet weight) was 0.60 ± 0.12 in the fundus 1.68 ± 0.33 in the antrum and 1.35 ± 0.30 in the dudenal bulb. Atrphy f the gastric mucsa was assciated with a reductin f the smatstatin cncentratin in the fundus and the antrum. N significant variatin was bserved in the present series f patients with gastric ulcer. Dudenal ulcer was assciated with a reductin f the smatstatin cncentratin in the antrum (P < 0.02). These results indicate that smatstatin is widely distributed frm fundus t dudenal bulb in adult human subjects and that lwer antral cncentratins are bserved in patients with dudenal ulcer. nitially islated frm bvine hypthalamus smatstatin (grwth hrmne release-inhibiting hrmne) was subsequently detected by immunflurescence in sme cells f the gastric and dudenal mucsa in man2 and by radiimmunassay in the upper digestive tract in rat. 3 N infrmatin n the physilgical r pathphysilgical rles f this peptide is yet available. Hwever the fact that synthetic smatstatin inhibits the release f several digestive hrmnes4--7 and the gastric 4 Hand pancreaticj J excrine secretins suggests that the endgenus peptide may be imprtant fr the cntrl f these mechanisms. n rder t investigate the distributin f smatstatin in the mucsa f the upper digestive tract in man the peptide cntent f mucsal specimens frm stmach Received August Accepted December This paper was presented in part at the Research Frum f the French Sciety f Gastrenterlgy Lausanne December 1976 the French Sciety f Endcrinlgy Paris January 1977 and the American Gastrenterlgical Assciatin Meeting in Trnt Can ada May Address requests fr reprints t: J. A. P. Chayvialle M.D. Department f Surgery University f Texas Medical Branch Gal vestn Texas The authrs thank Prfessr V. Mutt Prfessr J. C. Brwn and Dr. R. E. Chance fr the gift f peptides Dr. L. Pradayrl fr methdlgical advice Prfessr E. C. Saubier fr the surgical samples Dr. F. Berger and Dr. R. Trucht fr the histlgical cntrl f the specimens Dr. J. Orgiazzi Prfessr J. Turniaire M. Faivre and Dr. C. Gharib fr helping with the crss-reactivity studies. and prximal dudenum was measured radiimmunchemically in cntrl subjects and in patients with peptic ulcer. Methds Tissue Sampling Endscpic bipsies were btained after an vernight fast with an Olympus gastrdudenscpe GF-D2 (Olympus Crpratin f America New Hyde Park N. Y.) withut premedicatin. Grups f three specimens were taken fr smatstatin assay in the dudenal bulb (mean weight ± SE: 4.0 ± 0.12 mg) 3 cm befre the pylrus (4.5 ± 0.12) and 3 cm belw the cardia (5.0 ± 0.14). The bipsies were taken frm the psterir wall in the subjects with n lesin and frm the wall facing the lesin in the patients with peptic ulcer. One r tw specimens were simultaneusly cllected in the same area fr histlgical cntrl in additin t the bipsies required by the current clinical status. Surgical bipsies were taken 1 cm belw the pylrus (3 samples 47.6 ± 3.5 mg) 1 and 5 cm abve the pylrus (8 samples ± 2.5) and 3 and 8 cm abve the limit between antrum and fundus (5 t 10 bipsies accrding t the extent f the resectin 50.8 ± 3.1). All samples were immediately frzen n Dry ce and kept at -40 C until being prcessed. Subjects Endscpy. Bipsies were btained frm 52 subjects submitted t gastric endscpy and histlgical cntrl f the gastric mucsa fr diagnstic purpses. N macrscpic lesin was detected in 22 subjects subsequently segregated in tw grups accrding t the histlgical reprt frm tw pathlgists unaware f the data n smatstatin; 15 f them shwed n marked abnrmalities f the gastric mucsa (cntrls 5 fe- 13

2 14 CHAYVALLE ET AL. Vl. 75 N.1 males and 10 males mean age 43.2; range 22 t 70 years) whereas grss reductin f the nrmal gland ppulatin assciated with metaplasia and with varius degrees f inflammatin in the antral and/r fundic sampling areas was reprted in the 7 ther subjects (atrphy 2 females and 5 males mean age 50.6 range 40 t 73). An active uncmplicated dudenal ulcer was detected r cnfirmed in 21 patients (1 female and 20 males mean age 46.4 range 26 t 73); the cmmn histlgical picture in this grup included a nrmal fundic mucsa and mild t marked inflammatin f the antral mucsa but n severe atrphy. Nine patients had a nnmalignant gastric ulcer as shwn by multiple bipsies (2 females and 7 males mean age 51.2 range 31 t 76); mucsal alteratins including varius degrees f inflammatin atrphy and metaplasia were recrded at histlgy in this grup. Surgery. Specimens were btained frm 12 patients in whm a subttal gastrectmy was perfrmed fr a dudenal ulcer (7 males age range 24 t 51 years) r a benign gastric ulcer (5 males 42 t 48 years). Five additinal specimens were cllected frm patients with a gastric carcinma (3 males and 2 females age range 38 t 72 years) in whm the gastric bipsies taken at a minimal distance f 3 cm frm the edge f the tumr shwed severe atrphy f the glands and n tumr spread. Extractin Prcedure Smatstatin was extracted after a slight mdificatin f the methd f Arimura et al. 3 The bipsies were weighed while thawing and were immediately immersed in 200 Ll f biling distilled water fr 10 min. They were then hmgenized in 2 N acetic acid with a Kntes tissue grinder (size AA) (T. M. Kntes Vineland N. J.). The fine suspensin was left under agitatin fr 16 hr at 4 C and lyphilized. The dry residue was suspended in 0.05 M ammnium acetate buffer at ph 5.5 and centrifuged at 2000 rpm at 4 C fr 1 hr. Smatstatin was assayed in the supernatant fluid. Cntrl experiments were perfrmed t test the validity f this prcedure. The immunreactivity f the synthetic cyclic tetradecapeptide was tested befre and after heating at 100 C fr 10 min. The recvery f the peptide was estimated by adding and 8 ng f synthetic cyclic smatstatin t five grups f 14 aliquts f a hmgenate f gastric mucsa subsequently submitted t the extractin prcedure. N attempt was made t study the stability f smatstatin in tissues kept at rm temperature because all bipsies were immediately frzen. The variability f the smatstatin cncentratin frm bipsy t bipsy was estimated frm the cefficient f variatin fr the grups f three bipsies taken at the different levels in the cntrl subjects. Radiimmunassay fr Smatstatin Synthetic cyclic and synthetic linear smatstatin und 1- tyrsyl smatstatin were purchased frm Sern Pharm. Prap. GmbH (Freiburg/Breisgau West Germany); chlramine T and ethylenediamine tetraacetic acid disdium salt (EDTA) frm E. Merck (Darmstadt West Germany); bvine albumin frm Pviet Prd. B.V. (Amsterdam the Netherlands); 1- ethyl-3-(3-dimethylaminprpyl)carbdiimide HCl frm Sigma Chemical Cmpany (St. Luis M.); carbxymethyl cellulse CM 52 and diethylaminethyl cellulse DE 52 frm Whatman Ltd. (Maidstne England); S4 frm C.E.A. (Saclay France); G-25 Sephadex frm Pharmacia (Uppsala Sweden); synthetic human gastrin 1-17 frm mperial Chemical ndustries (Macclesfield England); dnkey antirabbit serum frm Wellcme (Beckenham England). The smatstatin antiserum was btained frm a New Zealand white rabbit twice injected with synthetic cyclic smatstatin (0.1 mg) cnjugated t bvine albumin (0.5 mg) thrugh carbdiimide cndensatin 12 using ethyl-cd (5 mg). The specificity f the antiserum was tested by incubating the fllwing hrmnes at the 100-ng per tube level: highly purified prcine vasactive intestinal peptide prcine chlecystkinin and prcine secretin (Prfessr V. Mutt) gastric inhibitry peptide (Prfessr J. C. Brwn) synthetic human gastrin 1-17 a partially purified preparatin f enterglucagn (Dr. D. Bataille) substance P (Bachem) bvine pancreatic plypeptide (Dr. R. E. Chance) adrencrtictrphic hrmne (Ciba) human grwth hrmne (Kabi) human chrinic gnadtrphin (SH) bvine insulin bvine prinsulin human mncmpnent insulin and bvine glucagn (Nv) bvine thyrtrpin (Armur) human fllicle-stimulating hrmne (LER 1366) human luteinizing hrmne (LER 960) luteinizing hrmne-releasing hrmne (Hffman) thyrtrpin-releasing hrmne (Rche) lysine-8-vaspressin (Sandz) arginine-vaspressin (Ferring) xytcin (Sandz) and angitensin (Ciba). 1-Tyrsyl smatstatin was labeled with after a slight mdificatin f the chlramine T methd. 1:3 T 1 Lg f peptide in 0.4 M phsphate buffer ph 7.5 were added in turn 0.5 mci f Lg f chlramine T and 20 Lg f sdium metabisulfite 15 sec later. The reactin mixture was then applied n a 0.6- by 5-cm CM 52 clumn equilibrated in 0.1 M glycine-hcl buffer ph 4.0. The idinated peptide was eluted thrugh a linear ph gradient frm 4.0 t 2.6. The mst immunreactive fractins as tested vernight in excess antiserum were diluted and stred at -40 C. Serial dilutins f idinated 1- tyrsyl smatstatin were incubated in rutine cnditins t test the immunreactivity fthe tracer. All assays were set up in 50 mm ammnium acetate buffer ph 5.5 with 1% hrse serum 1 mg f sdium azide per ml and 5 mm ethylenediaminetetraacetate (EDTA). Synthetic cyclic smatstatin was used as standard. The separatin f free frm antibdy-bund peptide was perfrmed with a duble antibdy prcedurel using nnimmune rabbit serum (final 1:2400) and a dnkey antirabbit serum (final 1:250). The tracer abut 1.8 pg per tube as estimated frm self-displacement studies and the secnd antibdy were added 24 and 48 hr respectively after the standard and the first antiserum. The within-assay and between-assay variatins were estimated by assaying 20 unknwn samples twice in the same assay r in tw different assays. Assay f Samples The mucsal extracts were tested at three dilutins in duplicate in rder t cmpare the reactivity f human smatstatin t that f the standard. Spare aliquts were tested at ther dilutins when necessary. All assays included samples frm the varius clinical grups. Results were expressed as nangram equivalents f synthetic cyclic smatstatin per milligram f fresh mucsa. ndividual mean values at each level tested were taken fr calculatin. The Mann Whitney U-test was used t cmpare the crrespnding values in the cntrls and the three clinical grups. Gel Filtratin Studies Fractins f dudenal antral and fundic mucsal extracts frm 3 cntrl subjects and 3 dudenal ulcer patients were pled t a final vlume f 1.8 ml arid applied n a 2- by 50-cm G25 medium Sephadex clumn equilibrated in 0.2 M acetic acid with 1% hrse serum and calibrated with bvine albumin synthetic cyclic smatstatin and 125. Fur-milliliter fractins were cllected and lyphilized. The residue was suspended in ammnium acetate buffer and centrifuged. Smatstatin was assayed in the supernatant fluid.

3 July 1978 SOMATOSTATN N GASTRODUODENAL MUCOSA 15 Ten surgical bipsies frm the antrum (ttal wet weight 723 mg) and prximal dudenum (247 mg) were extracted and the supernatant was chrmatgraphed as abve. Fractins 15 t 30 crrespnding t the immunreactivity eluted near the vid vlume were lyphilized suspended in ammnium acetate buffer centrifuged and pled. Aliquts (0.1 ml were either applied n a 0.6- by 100-cm G25 fine Sephadex clumn equilibrated in 0.2 M acetic acid with 1% hrse serum r incubated with 0.2 ml f 12 M urea fr 2 hr at 20 C and subsequently applied n the same clumn preladed with 1.5 ml f 8 M urea. The 0.5-ml fractins were lyphilized and tested fr smatstatin cntent. Gastrin mmunreactivity in Endscpic Specimens Cntrl experiments shwed that the recvery f synthetic human gastrin 1-17 added t tissue extracts was less than 15% in the present extractin cnditins. Hence the measurement f the gastrin cntent was restricted t fundic and antral endscpic specimens in rder t cntrl the reliability f tissue sampling at the gastric level in the endscpy patients. The antigastrin serum (28 C) was btained frm a rabbit immunized against synthetic human gastrin 2-17 (.C..) cnjugated t bvine albumin thrugh carbdiimide cndensatin. 12 Synthetic human gastrin 1-17 was used as standard and fr idinatin with by the chlramine T methd13 the tracer being purified by anin exchange chrmatgraphy.15 The separatin f free frm antibdy-bund hrmne was perfrmed with the same duble antibdy system as used fr the smatstatin assay. The characteristics f the gastrin assay are listed in table 1. Results Smatstatin assay. n the cnditins used fr the idinatin f -tyrsyl smatstatin 10 t 20% f the idine was incrprated int the peptide (fig. 1). After purificatin mre than 80% f the tracer was precipitated vernight in excess antiserum with a nnspecific binding f less than 5% (fig. 1). The slpes f the inhibitin curves btained when incubating serial dilutins f synthetic cyclic smatstatin and f tyrsyl smatstatin were nt dissimilar (fig. 2). Fr standard experiments the antismatstatin serum was used at a final dilutin f 1: Nne f the ther hrmnes tested interfered at the level f 100 ng per tube. The reactivity f synthetic linear smatstatin TABLE 1. Characteristics f the gastrin assay used fr the measurement f immunreactive gastrin in antral and fundic specimens frm endscpy patients Specificity f gastrin antiserum 28 C (mlar basis): Synthetic gastrin 1-17 (.C..) 1.0 Natural gastrin 1-17" 1.0 Synthetic gastrin Natural gastrin 1-34" 0.42 Natural gastrin Highly purified prcine chlecystkinin (Prf. V Mutt) Sensitivity Precisin (8 replicates CVb) Within-assay variatin Between-assay variatin (20 samples CV) 2.5 pg 3.8% 9.3% 13.4% " Curtesy f Dr. J. H. Walsh Center fr Ulcer Research and Educatin Ls Angeles Califrnia. CV cefficient f variatin. was 0.64 (D 50 cyclic frm = 1.0; fig. 3). The sensitivity f the assay was 25 pg per ml. The within-assay and between-assay variatins were respectively 9.0 and 12.3% (cefficient f variatin). The recvery f sma tstatin in the cnditins f extractin was 89.6 ± 2.3% (mean ± SE). Heating the standard t 100 C fr 10 min prduced n significant alteratin f its immunreactivity (fig. 3). Serial dilutins f synthetic cyclic smatstatin and f human mucsal extracts yielded parallel inhibitin curves (fig. 4). The mean (±SE) cefficients f variatin fr the grups f bipsies btained at endscpy in the cntrl grup were 33.4 ± 5.9% (dudenum) 24.4 ± 5.0% (antrum) and 37.8 ± 6.9% (fundus). Smatstatin in mucsal extracts. The validity f e " (280) l it a 18 h.. 80 n.. e r!i >i ; :! M J t 5 E 8 20 l * e; i i i F RAe TON S (2ML ) FG. 1. Elutin prfile f idinatin mixture n 0.6- by 5-cm CM 52 clumn. Starting buffer 0.1 M glycine-hcl ph 4.0. Arrw initiatin f linear ph gradient frm 4.0 t 2.6. Left axis radiactivity eluted per fractin. Right axis percentage f radiactivity bund vernight in excess antiserum. H '" N STU / TRACER DLUTON * * PG SOMATOSTATN / ML FG. 2. nhibitin curves btained with serial dilutins f (e) synthetic cyclic smatstatin and (*) idinated 1-tyrsyl smatstatin. Undiluted tracer preparatin: 3 x 10 6 cpm per m!. 80 i

4 16 CHAYVALLE ET AL. Vl. 75 N.1 * LNEAR CYCLC ::> a 40 '" z 0 CYCLC. 10Q C H E. 0) a \ it. \ \ '" 0 it. 0) a 20 g: *. H 0 '" 10 u '" ". 0 '" "0" '* PG SOMATOSTATN / ML FG. 3. nhibitin curves btained with serial dilutins f linear smatstatin and cyclic smatstatin befre and after heating at 100 C fr 10 min.!i 5 4 OQ Z... H / SAMPLE DLUTON i < "' "\ '" 0 30 '. 0- "\ "+ 40. " '\ '<:. ' '\ '" STD i '.." '.... '. '\ 20 '." "+ '+ i. '. 'A "<' "'- Of) N ' - fi <.J..: 10 fi P pg SOMATOSTATN / ml. '+ " A.'" '.. FG. 4. Cmparative immunreactivities f (STD) synthetic cyclic smatstatin and acetic extracts f human fundic (") antral (e) and dudenal (+) mucsa tested at 1:2 r 1:4 serial dilutins. tissue sampling at the antral and fundic levels in the endscpy subjects was cnfirmed by the clear-cut difference between the mean gastrin cncentratins in these tw areas (table 2). Smatstatin was detected in all specimens (fig. 5). n cntrls the highest cncentratin was bserved in the antrum (1.68 ± 0.33 ng per mg). The value in the prximal dudenum was slightly lwer (1.35 ± 0.3). Smatstatin was als present in the fundic mucsa at a cncentratin f abut ne-third the antral level (0.60 ± 0.12). n patients with severe atrphy f the antral and/r fundic mucsa in the sampling areas the smatstatin TABLE 2. Mean (±SE) cncentratins f immunreactive gastrin (nangrams per milligram f wet weight) in antral and fundic bipsies cllected in endscpy patients" Antrum Fundus Cntrl Atrphy Dudenal ulcer Gastric ulcer 2.2 ± 0.3 (37) 1.0 ± 0.19 (13) 1.98 ± 0.2 (51) 2.3 ± 0.32 (28) ± (28) ± (13) ± (49) ± (27) " Number f bipsies tested in each grup is indicated in parentheses. C A DU GU O'j D 0.4 p< c 0 D C:J " > p< l;'... D 0.8 p< 0.01 ANTRUM 0.4!O... '" 0 LJ u 1.6 a '" D DUODENUM [J - D FG. 5. Mean ± SE smatstatin cncentratins (nangrams per milligram f wet weight) in dudenal antral and fundic bipsies cllected frm 15 cntrl subjects (C) 12 patients with atrphy f the gastric mucsa in the sampling areas (A) 28 subjects with a dudenal ulcer (DU) and 14 patients with a benign gastric ulcer (GU) cntent was 0.41 ± 0.08 ng per mg in the antrum (-75.6% frm cntrl P < 0.01) and 0.24 ± 0.05 in the fundus (-60% P < 0.01). The dudenal cntent (1.21 ± 0.15) was nt different frm the value in the cntrl grup. The dudenal ulcer patients shwed n significant variatin f the smatstatin cncentratin in the dudenum and in the fundus. The mean antral cntent in this grup was 0.92 ± 0.09 ng per mg (-45% frm cntrl P < 0.02) the mean value recrded in the endscpy patients (0.87 ± 0.10 n = 21) being nt different frm the cncentratin in the surgical specimens (1.08 ± patients). The mean smatstatin cncentratins in the gastric ulcer patients were 1.69 ± 0.16 ng per mg in the dudenum 1.03 ± 0.23 in the antrum and 0.79 ± 0.23 in the fundus. Nne f these values was significantly different frm thse in the cntrl grup. Gel filtratin studies. When chrmatgraphed n G25 Sephadex the pls f dudenal antral and fundic mucsal extracts frm cntrl subjects and frm dudenal ulcer patients yielded similar elutin patterns

5 July 1978 SOMATOSTATN N GASTRODUODENAL MUCOSA 17 DUODENUM ANTRUM FUNDUS Z f- «f- Ul f- «Ul z l A S t -l c " 1. 0 Z -l -l. DU F RAe T ON S (4 ml) FG. 6. Elutin patterns f pls f dudenal antral and fundic extracts frm 3 cntrl subjects (C) and 3 patients with dudenal ulcer (DU) n a 2- by 50-cm G25 medium Sephadex clumn equilibrated in 0.2 M acetic acid with 1% hrse serum. The elutin vlumes f bvine albumin synthetic cyclic smatstatin and are shwn abve the tp middle diagram. (fig. 6). The mst immunreactive fractins were eluted at the level f and slightly behind the elutin zne f the synthetic cyclic tetradecapeptide. n sme samples abut 15% f the immunreactivity was detected near the vid vlume. Similar results were btained when 0.5 M acetic acid was used fr elutin. Rechrmatgraphy f fractins 15 t 30 crrespnding t the smatstatin eluted befre the tetradecapeptide vlume n a 2- by 50-cm G25 medium Sephadex clumn gave a majr peak f immunreactivity eluted slightly behind the cyclic smatstatin n a 0.6- by 100- cm G25 fine Sephadex clumn whether the rechrmatgraphed sample was preincubated with cncentrated urea r nt (fig. 7). Discussin Several radiimmunassay systems have been reprted fr the measurement f the smatstatin cncentratin in tissues. H8 The present assay was sensitive enugh fr the estimatin f smatstatin in bipsy specimens frm the human gastric and dudenal mucsa; the sensitivity f the present system culd have been increased by using tracer preparatins with higher specific activities but mild xidatin cnditins were rather chsen fr the idinatin f -tyrsyl smatstatin in rder t retain the immunreactivity f this synthetic peptide. As a cnsequence self-displacement experiments indicated that the tracer and the cyclic tetradecapeptide used as standard had similar immunreactivities as the substance(s) detected in mucsal extracts frm human stmach and dudenum. n cntrast t gastrin the acetic acid extractin ensured BSA ST 1! 06 i\j \ tilr.. /l \ firl 1\ t1 fl 1\ EFflUENT VOLUME (ml) FG. 7. Rechrmatgraphy (2 samples: --and ) f fractins 15 t 30 frm a pl f antral and dudenal bipsies chrmatgraphed accrding t figure 6. G25 fine Sephadex clumn (0.6 by 100 cm) equilibrated in 0.2 M acetic acid with 1% hrse serum. The elutin vlumes f bvine albumin synthetic cyclic smatstatin and 120dine are shwn at tp f the graph. adequate recvery f smatstatin. The main prblem encuntered in this study was the variability f the smatstatin cntent in bipsies taken at ne level in each individual althugh all samples were assayed by grups in rder t minimize the errr caused by inter-

6 18 CHAYVALLE ET AL. Vl. 75 N.1 assay variatins. This suggests that the distributin f smatstatin-prducing cells in the gastric and dudenal mucsa is nt unifrm. mmuncytchemical studies cnducted in man2. 19 and radiimmunlgical studies perfrmed in rats have shwn that smatstatin is detected in the stmach and the dudenum f these species the peptide being preferentially lcated in the antrum. This is cnfirmed by the present results. Hwever at variance with the results btained in rats3. 17 the smatstatin cncentratin in the mucsa f the dudenal bulb was clse t the value recrded in the antrum in the present cntrl subjects. Whether rat and man differ in this respect is uncertain. Bipsies frm the dudenal bulb nly were cllected thrugh the present study s that the pssibility f a smatstatin gradient alng the dudenum cannt be ruled ut. n cntrast t the distributin f gastrin substantial amunts f smatstatin were detected in the fundic mucsa f cntrl subjects. n view f the numerus effects f exgenus smatstatin n the excrine and endcrine secretins f the upper digestive tract the diffuse distributin f smatstatin frm fundus t dudenal bulb may thus reflect a wide range f physilgical-endcrine r paracrine - actins f the endgenus peptide. nvestigatins n the smatstatin cell ppulatin in patients with atrphy f the gastric mucsa have nt been reprted yet. Histlgically antral smatstatin cells are mainly lcated in the midpart f the mucsa2 but the preferential lcatin f these cells in the fundus has nt been specifically described. n the present study 7 f the endscpy subjects with n macrscpic lesins and 5 patients perated n fr a gastric carcinma shwed prfund atrphy f the gastric mucsa in the znes where the bipsies were taken fr smatstatin measurement. Althugh it is impssible at present t estimate the cntributin f factrs ther than lcal histlgy t the reductin f the mucsal smatstatin cntent the fact that the peptide cncentratins recrded at the fundic and antral levels in these patients were clearly lwer than the values in cntrls suggests that atrphic changes f the gastric mucsa are assciated with a reductin fthe tissue smatstatin cntent. Whether this variatin is attributable t increased release f the peptide r t a reductin f the smatstatin cell ppulatin will await studies investigating bth the density f these cells and their functinal state at the time f sampling. Sensitive detectin methds allwing fr the measurement f circulating smatstatin if any are needed t ascertain pssible abnrmalities f the metablism f this peptide in patients with peptic ulcer. n a preliminary histlgical study the rati f smatstatin cells t gastrin cells in the antral mucsa was fund t be increased in patients with gastric ulcer which was partly accunted fr by a reductin f the gastrin cell ppulatin and nrmal r decreased in dudenal ulcer patients with a nrmal r increased acid secretin respectively.20 n the present study the smatstatin cncentratins in the patients with gastric ulcer tended t be higher at the dudenal level and lwer in the antrum than the crrespnding values in cntrls but neither variatin reached significance when the series was cmpleted. n the 28 unselected dudenal ulcer patients a 40% reductin f the smatstatin cncentratin was bserved at the antral level. Whether this variatin simply reflects the antral mucsal inflammatin cmmnly bserved in these patients as well as in ther studies r a specific alteratin f the metablism f smatstatin will have t be delineated thrugh studies crrelating mucsal smatstatin cntent t acid secretin rate gastrin release and pathlgy f the antral mucsa. Whatever the mechanism will prve t be the reductin f the smatstatin cncentratin bserved in the present dudenal ulcer patients tgether with the decreased ptency f exgenus smatstatin n acid secretin and gastrin release bserved in ther studies23 indicates that smatstatin deserves further investigatin as t its relatin t the pathphysilgy f dudenal ulcer. When acetic extracts f gastric mucsa and pancreas frm rats were chrmatgraphed n G25 Sephadex sme immunreactivity was eluted in the vid vlume:l suggesting that varius mlecular frms f the peptide might be present in these tissues. n a subsequent study the "big" smatstatin detected in rat pancreas was fund t cnvert int a smaller mlecular species when the tissue extracts were incubated in 8 M urea. 24 Using similar chrmatgraphic cnditins we fund that part f the immunreactivity detected in human mucsal extracts was eluted near the vid vlume. Hwever the simple rechrmatgraphy f these fractins with and withut preincubatin in cncentrated urea yielded a majr immunreactive peak near the elutin vlume f the tetradecapeptide thus cnfirming that mst if nt all big smatstatin is an artifact attributable t nncvalent binding f the peptide t larger mlecules. n the present study the main immunreactive peak detected in extracts f human gastric and dudenal mucsa was eluted slightly behind the vlume f the synthetic cyclic tetradecapeptide. This may indicate that the natural human and synthetic peptides have slightly different charges r cnfiguratins. REFERENCES 1. Brazeau P Vale W Burgus R et al: Hypthalamic peptide that inhibits the secretin f immunreactive pituitary grwth hrmne. Science 179: Plak JM Pearse AGE Grimelius L et al: Grwth-hrmne release-inhibiting hrmne in gastrintestinal and pancreatic D-cells. Lancet 1: Arimura A Sat H Dupnt A et al: Smatstatin: abundance f immunreactive hrmne in rat stmach and pancreas. Science 189: Blm SR Mrtimer CH Thrner MO et al: nhibitin f gastrin and gastric acid secretin by grwth-hrmne releaseinhibiting hrmne. Lancet 2: Raptis S Dllinger HC Vn Berger L et al: Effects f smatstatin n gastric secretin and gastrin release in man. Digestin 13: Knturek SJ Tasler J Obtulwicz W et al: Effect f grwth hrmne release inhibiting hrmne n hrmnes stimulating excrine pancreatic secretin. J Clin nvest 58:

7 July 1978 SOMATOSTATN N GASTRODUODENAL MUCOSA Schlegel W Raptis S Harvey RF et al: nhibitin f chlecystkinin-pancrezymin release by smatstatin. Lancet 2: Knturek SJ Tasler J Cieszkwski M et al: Effect f grwth hrmne release-inhibiting hrmne n gastric secretin mucsal bld flw and serum gastrin. Gastrenterlgy 70: Creutzfeldt W Lankisch PG Flsch UR: nhibitin by smatstatin f pancreatic juice and enzyme secretin and gallbladder cntractin in man induced by secretin and chlecystkininpancrezymin administratin. Dtsch Med Wchenschr 100: Bden G Sivitz MC Owen OE et al: Smatstatin suppresses secretin and pancreatic excrine secretin. Science 190: Dmschke S Dmschke W Rsch W et al: nhibitin by smatstatin f secretin-stimulated pancreatic secretin in man: a study with pure pancreatic juice. Scand J Gastrenter12: Gdfriend TL Levine L Fasman GD: Antibdies t bradykinin and angitensin: a use f carbdiimides in immunlgy. Science 144: Hunter WM Greenwd FC: Preparatin f idine-131-labelled human grwth hrmne f high specific activity. Nature 194: Mrgan CR Lazarw A: mmunassay f insulin using a twantibdy system. Diabetes 13: Stadil F Rehfeld JF: Preparatin f 125 -labelled synthetic human gastrin fr radiimmunassay. Scand J Clin Lab nvest 30: Arimura A Sat H Cy DH et al: Radiimmunassay fr GHrelease inhibiting hrmne. Prc Sc Exp Bi Med 148: Krnheim S Berelwitz M Pimstne BL: A radiimmunassay fr grwth hrmne release-inhibiting hrmne: methd and quantitative tissue distributin. Clin Endcrinl 5: Patel YC Ra K Reichlin S: Smatstatin in human cerebrspinal fluid. N Engl J Med 296: Dubis MP Paulin C Dubis PM: Gastrintestinal smatstatin cells in the human fetus. Cell Tissue Res 166: Plak JM Blm SR McCrssan M et al: Studies n gastric D cell pathlgy (abstr). Gut 17: Hebbel R: Chrnic gastritis: its relatin t gastric and dudenal llcer and t gastric carcinma. Am J Path19: Magnus HA: The pathlgy f simple gastritis. J Pathl Bacteril 58: Knturek SJ Swierczek J Kwiecien N et al: Effect f smatstatin n meal-induced gastric secretin in dudenal ulcer patients (abstr). Gastrenterlgy 72: Dupnt A Alvarad-Urbina G: Cnversin f big pancreatic smatstatin withut peptide bnd cleavage int smatstatin tetradecapeptide. Life Sci 19: