Effect of opioid blockade on insulin metabolism in polycystic ovarian disease

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1 Human Reprductin vl.10 n.9 pp , 1995 Effect f piid blckade n insulin metablism in plycystic varian disease A.M.Fulghesu, M.Ciampelli, A.Frtini, F.Cucinelli, M.Guid, A.Carus, A.Lanzne 1 and S.Mancus 2 Department f Obstetrics and Gyneclgy, Cathlic University, L.g A. Gemelli 8, Rme 00168, and 'OASI Institute fr Research, Trina, Italy 2 T whm crrespndence shuld be addressed A ttal f 17 wmen affected by plycystic varian disease (PCOD) were studied t evaluate the invlvement f endgenus piids in the pathphysilgy f the hyperinsulinism in PCOD by administering naltrexne, an ral piid antagnist. An ral glucse tlerance test (OGTT) was perfrmed at baseline (n day 5 f the cycle) and repeated after 6 weeks f naltrexne administratin. Plasma glucse, insulin and cnnecting peptide (c-peptide) cncentratins were evaluated in all samples. Based n their insulinaemic respnse t OGTT, patients were classified as hyperinsulinaemic r nrminsulinaemic. Naltrexne treatment significantly (P < 0.007) reduced the insulin respnse t OGTT in the hyperinsulinaemic grup withut affecting the c- peptide incremental area; in the nrminsulinaemic grup there was a slight, but nt significant, increase in bth c- peptide and insulin incremental areas. The tw grups shwed similar c-peptide incremental areas after naltrexne treatment. There was n significant difference in the c- peptiderinsulin incremental areas mlar rati between the tw grups; after treatment, a significant increase in this rati was bserved in bth grups. When we cnsidered the data as an expressin f the fractinal hepatic extractin f insulin, we fund a lwer value fr hyperinsulinaemic in cmparisn with nrminsulinaemic patients (nt significant), and a significant (P < 0.01) imprvement f this parameter in the hyperinsulinaemic grup after naltrexne administratin. In cnclusin, we suggest that the cntributin t hyperinsulinaemia in PCOD patients may be at least in part due t bth increased pancreatic secretin and reduced hepatic remval f insulin. Chrnic pharmaclgical inhibitin f piid tne culd imprve the insulin plasma cncentratin by acting chiefly n the liver metablism f insulin in hyperinsulinaemic patients. Key wrds: c-peptide/insulin/piids/plycystic varian disease Intrductin Plycystic varian disease (PCOD) is a syndrme characterized by chrnic anvulatin, elevated serum andrgen cncentratins, inapprpriate gnadtrphin secretin (Gldzieher, 1981) and metablic effects such as hyperinsulinism and insulin resistance (Barbieri and Ryan, 1983). Hyperinsulinaemia can be explained by increased insulin secretin. Hwever, befre reaching the periphery, insulin has t traverse the liver where a variable extractin takes place (Plnsky and Rubenstein, 1984), s it is als pssible that abnrmal hepatic metablism f insulin may cntribute t the peripheral hyperinsulinaemia. It is well knwn that insulin and cnnecting peptide (cpeptide) are secreted in equimlar cncentratins by the pancreatic p-cells (Rubenstein et al., 1969). Mrever, in cntrast t insulin, very little amunts f c-peptide are metablized by the liver (Kiihl et al., 1977), whereas the kidney is the majr site f degradatin (Faber et al., 1977). Therefre, the simultaneus determinatin f insulin and c-peptide plasma cncentratins may permit the analysis f the cntributin t the hyperinsulinaemia f pancreatic secretin as well as hepatic insulin remval (Faber et al., 1981). The demnstratin f }-endrphin in human endcrine pancreas (Bruni etal., 1979) and the finding f elevated plasma immunreactive P-endrphin in PCOD patients cmpared with cntrl subjects (Givens et al., 1980; Aleem and Mclntsh, 1984) suggest a pssible invlvement f endgenus piates in glycregulatin. In ur previus studies, we demnstrated that the chrnic inhibitin f piid tne by the piid antagnist naltrexne was able t reduce the insulin respnse t an ral glucse tlerance test (OGTT) in hyperinsulinaemic wmen suffering frm PCOD withut affecting their glycaemic levels (Fulghesu etal., 1993). The aim f this study was t evaluate whether PCOD hyperinsulinism is caused by exaggerated pancreatic secretin and/r reduced hepatic insulin remval, as well as the effect f lng-term treatment with the piid antagnist naltrexne. Materials and methds We studied 17 cnsecutive wmen affected by PCOD, aged years. Infrmed cnsent was btained frm each patient. All the wmen were in gd health, euthyrid and had a nrmal glmerular filtratin rate, as demnstrated by nrmal creatinine clearance levels. Nne f the patients had taken any medicatin knwn t affect carbhydrate metablism fr at least 3 mnths befre the study. All patients had spntaneus nset f puberty and nrmal sexual develpment, and all had been affected by ligmenrrhea with chrnic anvulatin since puberty. N patient shwed evidence f acanthsis nigricans. Obesity was defined as a bdy mass index (BMI) >25 (nrmal range 19-25), calculated accrding t the frmula bdy weight/height 2 (kg/m 2 ). PCOD was diagnsed by clinical findings (presence f amenrrhea r ligmenrrhea and hirsutism), plasma andrgen cncentratins Oxfrd University Press 2253

2 A.M.Fulghesu et al. at the upper limits f r abve the nrmal range (andrstenedine nml/1, teststerne nml/1) and bilaterally nrmal r enlarged varies with at least seven t 10 micrcysts (<5 mm in diameter) at the time f ultrasngraphy and/r laparscpy. A nrmal luteinizing hrmne (LH):fllicle-stimulating hrmne (FSH) rati was nt cnsidered an exclusin criterin. All studies were perfrmed in the fllicular phase n cycle days 5-8 after prgestin-induced menses. The patients were hspitalized; after fllwing a standard carbhydrate diet (300 g/day) fr 3 days and fasting vernight fr h they underwent an OGTT and basal hrmne assay. The patients then left the hspital and had 6-7 weeks f treatment with 50 mg/day naltrexne, an ral narctic antagnist (Antaxne; Simes, Vicenza, Italy). In the absence f spntaneus menstrual bleeding, a prgestin test was repeated after 5 weeks f naltrexne treatment. Fllwing cntinuatin f the treatment, the OGTT and the basal hrmne assay were repeated in a secnd hspitalizatin at menstrual days 6-7. The OGTTs were perfrmed as fllws. At 8:00 a.m. an in-dwelling catheter was inserted in the antecubital vein f ne arm. Basal bld samples were cllected and, after ingestin f 75 g glucse in 150 ml f water within 5 min, at 30, 60, 90, 120, 180 and 240 min. Samples fr glucse were assayed immediately, whereas samples fr the ther determinatins were prmptly centrifuged and the plasma was stred at -20 C until assayed. Insulin, glucse and c-peptide cncentratins were assayed in all bld samples. Furthermre LH, FSH, estradil, 17-hydrxyprgesterne, teststerne, dihydrepiandrsterne (DHEA)-sulphate, andrstenedine, sex hrmne binding glbulin and crtisl plasma cncentratins were als determined in basal cnditins and after naltrexne treatment. All hrmne cncentratins were determined by cmmercial radiimmunassay kits (Radim, Pmezia, Italy). Glucse cncentratins were determined by the glucse xidase technique. Fr each determinatin, all samples frm the same patient were assayed simultaneusly. The intra- and interassay cefficients f variatin were <8 and 15% fr all hrmnes respectively. A nrmal glycaemic respnse t OGTT was defined accrding t the criteria f the Natinal Diabetes Data Grup (1979). All results are expressed as mean ± SD. Insulin, glucse and c- peptide plasma cncentratins were als expressed as area under the curve (AUC) after glucse ingestin, calculated by the trapezidal rule. The patients were classified as nrm- r hyperinsulinaemic accrding t their insulin respnse t the OGTT, cnsidering a cutff value f pml/1 X 240 min fr the AUC, as established by standard prcedures in ur labratry (Lanzne et al., 1991). Hepatic insulin extractin was estimated frm: (i) the c-peptide: insulin mlar ratis in the fasting state and after glucse lading; and (ii) the difference between the incremental areas f c-peptide and insulin divided by the incremental area f c-peptide, as prpsed by ther authrs (Faber et al., 1981; Bnra et al., 1984). The incremental area was calculated by the difference between AUC and basal AUC (basal AUC = area f the curve due t the basal unstimulated secretin and calculated assuming a cnstant value during a 4 h perid). Statistical analysis was perfrmed using the nn-parametric Mann- Whitney test fr tw grup cmparisns; within-grup cmparisns were perfrmed by the Wilcxn matched pairs, signed rank test. Linear regressin analysis was used t analyse pssible crrelatins between endcrine findings. Partial crrelatin was used t describe the relatinship between tw variables while adjusting fr the effects f ne r mre additinal variables. Differences were cnsidered significant at P < Results Based n the insulinaemic respnse t OGTT, patients were classified as hyperinsulinaemic (n = 10; 59%) r nrminsulinaemic (n = 7; 41%). Table I shws the endcrine and metablic parameters in the tw grups at baseline and after 6 weeks f naltrexne therapy. Similar BMI values were fund in the tw grups: the nrminsulinaemic grup included three bese patients (43%) and fur patients f nrmal weight (57%), whereas the hyperinsulinaemic grup included seven bese and three nnbese patients. N differences in hrmne cncentratins were fund in the tw grups, whereas plasma sex hrmne binding glbulin cncentratins were greater in the nrminsulinaemic grup (f < 0.05). N endcrine parameters had changed after lng-term treatment. Als, the BMI did nt change during treatment. N differences in the glmerular filtratin rate were bserved between the grups and in relatin t treatment (creatinine clearance: nrm-pre 98.7 ± 8.3 versus hyper-pre ± 11.5; nrm-pst ± 9.7 versus hyper-pst ± 15.3 ml/min). Cncerning the glycaemic respnse t OGTT, tw patients shwed impaired glucse tlerance (IGT) while the thers had a nrmal glucse tlerance; patients did nt shw a change in their glucse tlerance after therapy. Naltrexne treatment reduced the fasting and AUC insulin plasma levels, nly in the hyperinsulinaemic grup, ablishing the difference between nrm- and hyperinsulinaemic patients. Figure 1A shws the incremental areas f insulin and c- peptide cncentratins in the tw grups befre and after naltrexne administratin. In Figure IB is shwn the mlar rati between the incremental areas f c-peptide and insulin, and fractinal hepatic insulin extractin calculated frm these incremental areas (Faber et al., 1981). It is clearly demnstrated that, in basal cnditins, hyperinsulinaemic patients were characterized by significantly greater values f c-peptide and insulin incremental areas in cmparisn with the nrminsulinaemic grup. Mrever, despite a significant reductin in the insulin incremental area in hyperinsulinaemic patients after naltrexne therapy, n variatin in the c-peptide incremental area (pre = ± versus pst = ± pml/1 X 240 min) was bserved. In the nrminsulinaemic grup, there was a slight, but nt significant, increase in bth c-peptide and insulin incremental areas. In particular, the nrm- and hyperinsulinaemic grups shwed similar c-peptide incremental areas after naltrexne treatment. In the hyperinsulinaemic grup, the c-peptide: insulin incremental areas mlar rati was slightly lwer, but nt significantly, cmpared with the nrminsulinaemic grup. After treatment, a significant increase in this rati was bserved in bth grups. In the nrminsulinaemic patients this change was due principally t a higher c-peptide incremental area after treatment, while in the hyperinsulinaemic grup it was ascribed t a reductin in insulin cncentratin. When we expressed the data as the fractinal hepatic insulin extractin, we btained a lwer, but nt significant, value fr

3 Opiids and insulin metablism in plycystic varian disease Table I. Metablic and endcrine features f the studied plycystic varian disrder patients befre and after naltrexne treatment Nrminsulinaemic (n = 7) Befre treatment After treatment Hyperinsulinaemic (n = Befre treatment 10) After treatment Bdy mass index (kg/m 2 ) Fasting insulin (pml/1) Fasting c-peptide (pml/1) Insulin area under curve (pml/1 x 240 min x 10 3 ) Glucse area under curve (mml/1 x 240 min) Sex hrmne binding glbulin (nml/1) Fllicle stimulating hrmne (IU/1) Luteinizing hrmne (IU/1) Prlactin ( ig/l) Oestradil (pml/1) Crtisl (nml/1) Teststerne (nml/1) Andrstenedine (nml/1) 17-Hydrxyprgesterne (nml/1) DHEA-sulphate (nml/1) 27.7 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 1.70 DHEA = dihydrepiandrsterne. "P < 0.05 between nrminsulinaemic and hyperinsulinaemic grups. b P < between nrminsulinaemic and hyperinsulinaemic grups. C P < within hyperinsulinaemic grup. the hyperinsulinaemic cmpared with the nrminsulinaemic grup, and a significant imprvement f this parameter in the hyperinsulinaemic patients after naltrexne administratin. In basal cnditins, we als fund a significant negative linear crrelatin between the incremental areas f insulin and hepatic insulin extractin (Figure 2). In cntrast, besity was related t neither incremental insulin area nr hepatic extractin. Mrever we als fund a significant (P < 0.002) partial crrelatin between incremental areas f insulin and hepatic insulin extractin, cntrlling fr BMI. Insulin and c-peptide incremental areas were nt related t each ther in basal cnditins, but after naltrexne treatment there was a significant psitive linear crrelatin between these tw parameters (Figure 3) ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 72.5 a ± ± b ± ± 11.90" 5.32 ± ± ± ± ± ± ± ± ± 2.42 Discussin PCOD is characterized by chrnic anvulatin, raised serum andrgen cncentratins and an elevated incidence f besity and hyperinsulinism (Burghen et al., 1984). Hwever, the pattern f exaggerated circulating insulin is represented hetergeneusly in PCO, affecting mst f the bese as well as a significant prprtin f the lean subjects (Barbieri and Ryan, 1983). Several studies have shwn that piates are invlved in glycmetablic hmestasis by acting n insulin and glucagn utput by the endcrine pancreas (Giuglian et al., 1987). Since the circulating cncentratins f B-endrphins seem t be altered in PCOD, a pssible effect f piates n insulin secretin has been suggested (Givens et al., 1987). In ur previus studies (Lanzne et al., 1991; Fulghesu et al., 1993), an acute and lng-term blckade f piate receptrs led t a significant reductin f the insulin respnse t OGTT in hyperinsulinaemic PCOD subjects withut any effect in nrmpst pst ± ± ± ± 54.9 C ± ± ± ± ± ± ± ± ± ± ± 2.70 Figure 1. (A) Insulin incremental area (left) and c-peptide incremental area (right) after basal glucse lading and after naltrexne treatment in hyperinsulinaemic ( ) and nrminsulinaemic patients with plycystic varian disease. (B) c-peptide:insulin incremental area mlar rati (left) and (c-peptide - insulin)/c-peptide incremental area in the same cnditins and in the same grups as in (A). Data are expressed as mean ± SD. c-pep = c-peptide. insulinaemic patients. We have als dcumented that, in this experimental cnditin, the reductin in insulin secretin failed t induce a hrmnal change in such hyperandrgenized patients. In this study, we wanted t explre the pssible mechanism 2255

4 A.M.Fulghesu et al. 0 - ^<> \ ^^\ ^S. r=-0.69 P< i t INSUUN INCREMENTAL AREA (pmul X *) Figure 2. Linear regressin between insulin incremental area and (c-peptide - insulin)/c-peptide incremental area in basal cnditins in the patients studied b r=0.56 />< INSULIN INCREMENTAL AREA (pmt/1 > 240" «10") Figure 3. Linear regressin between insulin incremental area and c-peptide incremental area befre (O) and after ( ) naltrexne treatment in the patients studied. There was a significant psitive linear crrelatin after naltrexne treatment. NS = nt significant \ \ 300 by which piates culd be invlved in the pathphysilgical events f the syndrme. We fund that a chrnic inhibitin f piid tne reduces hyperinsulinaemia in PCOD patients, prbably by influencing hepatic extractin f insulin mre than pancreatic secretin. In fact, despite a significant reductin f insulin secretin, there was n mdificatin f c-peptide secretin after naltrexne treatment. Mrever, the specific parameters f liver insulin metablism were imprved significantly with piid antagnist administratin. It is als pssible that piids influence the metablic clearance f c-peptide. Mst c-peptide is extracted by the kidneys and n significant change in the glmerular filtratin rate was recrded after naltrexne administratin. Furthermre, althugh c-peptide extractin by the liver cannt be excluded, it has been demnstrated that this extractin is at least 50% lwer than that f insulin (Plnsky and Rubenstein, 1984). Thus, even thugh the assumptin f the c-peptide:insulin rati f their mlar cncentratins r their incremental areas may raise sme criticisms in terms f mathematical calculatin (Plnsky and Rubenstein, 1984), it can reasnably be cnsidered as a bilgical index f the hepatic extractin f pancreatic hrmnes. Mrever, since it is generally agreed that altered insulin hepatic remval is related t besity (Faber et al., 1981; Bnra et al, 1984), it is pssible that the reductin f exaggerated insulin secretin with naltrexne in ur patients may be influenced mre by the degree f besity than by insulinaemic levels. The data in ur study culd suggest that in PCOD patients, hyperinsulinism can influence hepatic remval mre than besity. In fact, a significant negative linear crrelatin between insulin incremental area and insulin hepatic extractin was fund, whereas we failed t demnstrate a crrelatin between insulin hepatic extractin and BMI. Mrever, a significant partial crrelatin between insulinaemic levels and insulin liver metablism, cntrlling fr BMI, has been reprted. In cmparisn, nrm- and hyperinsulinaemic patients had similar BMI values and patients did nt recrd a bdy weight mdificatin after naltrexne therapy. In this study, we have als reprted a lack f linear crrelatin between insulin and c-peptide incremental areas in basal cnditins, whereas we have fund a significant psitive linear crrelatin between these tw hrmnes after naltrexne administratin. A hypthesis t explain these data is that in basal cnditins, patients with high fasting and stimulated cncentratins f insulin had an altered liver metablism f insulin, whereas after naltrexne administratin the insulinaemic levels were a direct functin f pancreatic p-cell secretin, as there had been an imprvement f insulin metablism in the liver. It is als well knwn that, in cntrast t c-peptide, insulin has specific receptrs n peripheral tissue cells (Faber et al., 1981), as well as n hepatcyte membranes (Terns and Steiner, 1975). Thus, hyperinsulinaemia culd als be caused by peripheral insulin resistance, which increases the demand t pancreatic p-cells fr the defect t be vercme and euglycaemia t be maintained (Dunaif et al., 1989; Giuglian et al., 1991). It is cnceivable that this situatin leads t the dwnregulatin f hepatic insulin receptrs, which in turn culd be respnsible fr impaired insulin remval (Bnra et al., 1984). Therefre a pssible effect f piid antagnist n peripheral tissue receptrs cannt be excluded. In cnclusin, in this study it is suggested that the hyperinsulinaemia in PCOD patients may be caused by, at least in part, bth increased pancreatic secretin and reduced hepatic remval f insulin. Chrnic pharmaclgical inhibitin f piid tne culd imprve the insulin cncentratin in plasma by acting chiefly n insulin metablism in the liver f such hyperinsulinaemic subjects. Further studies are needed t clarify whether this effect is directly dependent n the blckade f piate receptrs r whether it might als be ascribed indirectly t ther mechanisms. References Aleem, F.A. and Mclntsh, T. (1984) Elevated plasma levels f P endrphins in a grup f wmen with plycystic varian disease. Fertil. Slerii, 42, Barbieri, R.L. and Ryan, K.J. (1983) Hyperandrgenism, insulin resistance and acanthsis nigricans syndrme: a cmmn endcrinpathy with distinct pathphysilgic features. Am. J. Obstet. Gyneci, 147,

5 Opiids and insulin metablism in plycystic varian disease Bnra, E., Zavarni, I., Bruschi, F., Alpi, O., Pezzarssa, A., Guerra, C, Dall'Agli, E., Cscelli, C. and Butturini, U. (1984) Peripheral hyperinsulinemia f simple besity: pancreatic hypersecretin r impaired insulin metablism?/ Clin. Endcrinl. Metab., 59, Bruni, J.F., Watkins, W.B. and Yen, S.S.C. (1979) p Endrphin in the human pancreas. J. Clin. Endcrinl. Metab., 49, Burghen, C.A., Givens, J.R. and Kitabchi, A.E. (1984) Crrelatin f hyperandrgenism with hyperinsulinism in plycystic varian disease. J. Clin. Endcrinl Metab., 20, Dunaif, A., Segal, K.R., Futterweit, W. and Dbrjansky, A. (1989) Prfund peripheral insulin resistance, independent f besity, in plycystic vary syndrme. Diabetes, 38, Faber, O.K., Kehlet, H., Madsbad, S. and Binder, C. (1977) Kinetics f human c-peptide in man. Diabetes, 27, Faber, O.K., Christensen, K., Kehletm, H., Madsbad, S. and Brinder, C. (1981) Decreased insulin remval cntributes t hyperinsulinemia in besity. J. Clin. Endcrinl. Metab., 53, Fulghesu, A.M., Lanzne, A., Cucinelli, F., Carus, A. and Mancus, S. (1993) Lng term naltrexne treatment reduces the exaggerated insulin secretin in patients with plycystic varian disease. Obstet. Gyneci, 82, Giuglian, D., Ceriell, A., Salvatre, T., Paliss, G., D'Onfri, F. and Lefebvre, P. (1987) P-Endrphin infusin restres acute insulin respnses t glucse in type-2 diabetes mellitus. J. Clin. Endcrinl. Metab., 64, Giuglian, D., Czzlin, D., Trella, R., Lefebvre, P.J., Franchimnt, P. and D'Onfri, F. (1991) Persistence f altered metablic respnse t P- endrphin after nrmalizatin f bdy weight in human besity. Ada Endcrinl., 124, Givens, J.R., Wiedemann, E., Andersen, R.M. and Kitabchi, A.E. (1980) P Endrphin and P lipthrpin plasma levels in hirsute wmen: crrelatin with bdy weight. J. Clin. Endcrinl. Metab., 50, Givens, J.R., Kurtz, B.R., Kitabchi, A.E., Tittle, J.B., Karas, T.S., Mirchell, J.A. and Hwes, J.F. (1987) Reductin f hyperinsulinemia and insulin resistance by piate receptr blckade. J. Clin. Endcrinl. Metab., 64, Gldzieher, J.W. (1981) Plycystic varian disease. Fertil. Steril., 35, Kiihl, C, Faber, O.K., Hrnnes, P. and Lindkaer Jensen, S. (1977) C-Peptide metablism and the liver. Diabetes, 27, Lanzne, A., Fulghesu, A.M., Frtini, A., Cutill, G., Cucinelli, F., Di Simne, N., Carus, A. and Mancus, S. (1991) Effect f piate receptr blckade n the insulin respnse t ral glucse lad in plycystic varian disease. Hum. Reprd., 6, Natinal Diabetes Data Grup (1979) Classificatin and diagnsis f diabetes mellitus and ther categries f glucse intlerance. Diabetes, 28, Plnsky, K.S. and Rubenstein, A.H. (1984) C-Peptide as a measure f the secretin and hepatic extractin f insulin. Pitfalls and limitatins. Diabetes, 33, Rubenstein, A.H., Clark, J.L., Melani, F. and Steiner, D.F. (1969) Secretin f prinsulin C-peptide by pancreatic p cells and its circulatin in bld. Nature, 224, Terris, S. and Steiner, D.F. (1975) Binding and degradatin f 125 I-insulin by rat hepatcyte. J. Bil. Chem., 250, Received n December 29, 1994; accepted n June 7,