Duodenocolic fistula healing by pentadecapeptide BPC 157 in rats. A cytoprotection viewpoint.

Using duodenocolic fistula in rats, this study attempts to highlight the particular cytoprotection aspects of the healing of fistulas and therapy potential of the stable gastric pentadecapeptide BPC 157, a cytoprotection mediator (i.e. upgrading minor vessels to induce healing at both fistula's sides). Upon duodenocolic fistula creation (two 'perforated' lesions put together) (assessed at 3, 6, 9, 12, and 15 min), BPC 157, given locally at the fistula, or intragastrically (10 µg/kg, 10 ng/kg), rapidly induces vessel 'recruitment', 'running' toward the defect, simultaneously at duodenum and colon, providing numerous collaterals and branching. The mRNA expression studies done at that time provided strongly elevated (nitric oxide synthase 2) and decreased (cyclooxygenase-2, vascular endothelial growth factor A, nitric oxide synthase (NOS)-1, NOS-3, nuclear factor-kappa-B-activating protein) gene expression. As therapy, rats with duodenocolic fistulas, received BPC 157 10 µg/kg, 10 ng/kg, per-orally, in drinking water till sacrifice, or alternatively, intraperitoneally, first application at 30 min after surgery, last at 24 h before sacrifice, at day 1, 3, 7, 14, 21, and 28. Controls exhibited both defects persisting, continuous fistula leakage, diarrhea, continuous weight loss, advanced adhesion formation and intestinal obstruction. Contrary, all BPC 157-treated rats have closed both defects, duodenal and colonic, no fistula leakage (finally, maximal instilled volume corresponds to healthy rats), no cachexia, the same weight as before surgery, no diarrhea, markedly less adhesion formation and intestinal passage obstruction. Thus, BPC 157 regimens resolve the duodenal/colon lesions and duodenocolic fistulas in rats, and rapid vessels recovery appears as the essential point in the implementation of the cytoprotection concept in the fistula therapy.

Novel insight into Robert's cytoprotection: complex therapeutic effect of cytoprotective pentadecapeptide pentadecapeptide BPC 157 in rats with perforated stomach throughout modulation of nitric oxide-system. Comparison with L-arginine, ranitidine and pantoprazole therapy and L-NG-nitro-L-arginine methyl ester worsening.

Surgically perforated stomach (since direct injury in rats until persisting defect and huge adhesions (day 1, day 7)) fairly represent an unresolved cytoprotection issue, and thereby, we focused resolving of the immediate triad, particular vascular failure (vessels 'disappear'/empty), prolonged bleeding, debilitated defect large widening. Agents (mg/kg) or saline (controls) were given at 1 min post-injury as an abdominal bath (10 ml/rat throughout 2 min). Within 1 - 15 min post-injury period, with cytoprotective BPC 157 (0.01 µg), the rapidly restored vessels 'run' (vessels filled/reappeared) toward the perforated defect, and there is less bleeding, and defect contraction; advanced perforated lesion healing (day 1) to complete healing (day 7), and less adhesions. With pantoprazole (10 mg), early (vessels (worsening), bleeding (prolongation), defect (attenuated widening)) effect means eventual lesions and adhesions severity as in controls. Ranitidine (10 mg) early effect (vessels (improvement), bleeding (less bleeding), defect (eliminated widening, defect not changed)) means final lesions attenuation, but not complete healing, less adhesions. L-NAME (5 mg) early (vessels worsening, less bleeding, attenuated defect widening) and final (lesions aggravation, more adhesions) effect, versus L-arginine (100 mg) early (vessels improvement, more bleeding, attenuated defect widening) and final (lesions attenuation, less adhesions) effect, combined few simultaneously occurring nitric oxide (NO)-system distinct processes. Finally, in the stomach tissue surrounding defect, increased malondialdehyde (MDA)- and decreased NO-values, BPC 157 reversed to the normal healthy values, and mRNA expression studies (Cox2, VEGFa, Nos1, Nos 2, Nos3, Nkap (NF-kappa-B-activating protein gene)), done at that very early post-perforation-time, indicate a way how BPC 157 may act beneficially in the perforated stomach lesion throughout NO- and prostaglandinds-system.

Ethanol gastric lesion aggravated by lung injury in rat. Therapy effect of antiulcer agents.

Hemorrhagic mucosal lesions in the stomach in the rat induced by an intragastrical application of 1 ml of 50 or 75% ethanol were aggravated by preceding lung damage provoked by an intratracheal instillation of pyrogen-free saline or HCl (pH 1.75) or 50-h exposure to 100% oxygen. Due to the particular preceding aggravating circumstances, these lesions were taken to be of a special kind, rather than ordinary. So far, it is not known whether and how antiulcer agents may influence these lesions. Rats received an intratracheal (i.t.) HCl instillation [1.5 ml/kg HCl (pH 1.75)] (lung-lesion), and an intragastric instillation of 96% ethanol (gastric lesion; 1 ml/rat, 24 h after i.t. HCl instillation), and were sacrificed 1 h after ethanol. Basically, in lung injured rats, the subsequent ethanol-gastric lesion was markedly aggravated. This aggravation, however, in turn, did not affect the severity of the lung lesions in the further period, at least for a 1-h observation. Taking intratracheal HCl-instillation as time 0, a gastric pentadecapeptide, GEPPPGKPADDAGLV, M.W.1419, coded BPC 157 (PL-10, PLD-116; 10 microg, 10 ng, 10 pg), ranitidine (10 mg), atropine (10 mg), omeprazole (10 mg), were given [/kg, intraperitoneally (i.p.)] (1) once, only prophylactically [as a pre-treatment (at -1 h), or as a co-treatment (at 0)], or only therapeutically (at +18 h or +24 h); (2) repeatedly, combining prophylactic/therapeutic regimens [(-1 h)+(+24 h) or (0)+(+24 h)], or therapeutic/therapeutic regimens [(+18 h)+(+24 h)]. In general, the antiulcer agents did protect against ethanol gastric lesions regardless of the presence of the severe lung injury, in all of the used regimens. Of note, combining their prophylactic and salutary regimens (at -1 h/+24 h, or at 0/+24 h) may increase the antiulcer potential, and the effect that had been not seen already with single application, became prominent after repeated treatment.

Lung lesions and anti-ulcer agents beneficial effect: anti-ulcer agents pentadecapeptide BPC 157, ranitidine, omeprazole and atropine ameliorate lung lesion in rats.

Anti-ulcer agents may likely attenuate lesions outside the gastrointestinal tract, since they had protected gastrectomized rats (a "direct cytoprotective effect"). Therefore, their therapeutic potential in lung/stomach lesions were shown. Rats received an intratracheal (i.t.) HCl instillation [1.5 ml/kg HCl (pH 1.75)] (lung lesion), and an intragastric (i.g.) instillation of 96% ethanol (gastric lesion; 1 ml/rat, 24 h after i.t. HCl instillation), then sacrificed 1 h after ethanol. Basically, in lung-injured rats, the subsequent ethanol-gastric lesion was markedly aggravated. This aggravation, however, in turn, did not affect the severity of the lung lesions in the further period, at least for 1 h of observation. Taking intratracheal HCl-instillation as time 0, a gastric pentadecapeptide, GEPPPGKPADDAGLV, M.W.1419, coded BPC 157 (10 microg, 10 ng, 10 pg), ranitidine (10 mg), atropine (10 mg), omeprazole (10 mg), were given [/kg, intraperitoneally (i.p.)] (i) once, only prophylactically [as a pre-treatment (at -1h)], or as a co-treatment [at 0)], or only therapeutically (at +18h or +24 h); (ii) repeatedly, combining prophylactic/therapeutic regimens [(-1 h)+(+24 h)] or [(0)+(+24 h)], or therapeutic/therapeutic regimens [(+18 h)+(+24 h)]. For all agents, combining their prophylactic and salutary regimens (at -1 h/+24 h, or at 0/+24 h) attenuated lung lesions; even if effect had been not seen already with a single application, it became prominent after repeated treatment. In single application studies, relative to controls, a co-treatment (except to omeprazole), a pre-treatment (at -1 h) (pentadecapeptide BPC 157 and atropine, but not ranitidine and omeprazole) regularly attenuated, while therapeutically, atropine (at +18 h), pentadecapeptide BPC 157 highest dose and omeprazole (at +24 h), reversed the otherwise more severe lung lesions.

Cysteamine-colon and cysteamine-duodenum lesions in rats. Attenuation by gastric pentadecapeptide BPC 157, cimetidine, ranitidine, atropine, omeprazole, sulphasalazine and methylprednisolone.

Recently, we showed cysteamine-duodenal lesions without gastric acid, since they were induced also in gastrectomized rats, as in naive rats, and they were inhibited by the novel stomach pentadecapeptide BPC 157 as well as standard antiulcer drugs (i.e. cimetidine, ranitidine, omeprazole, bromocriptine, atropine). Therefore, as an advantage of considering cysteamine as a directly acting cytotoxic agent and mentioned agents as direct cytoprotective agents, the present focus was on the ulcerogenic effect of cysteamine and protective effect of gastroduodenal antiulcer agents outside upper gastrointestinal tract (i.e. in colon). Intrarectal administration of the cysteamine (200 or 400 mg/kg b.w) produced severe colon lesions (i.e. transmural inflammation with serosal involvement) in rats (30 min-72 h-experimental period), apparently distinctive from smaller lesions after non-specific irritant enema [diluted HCl solution, pH 3.8 (adjusted to pH of cysteamine solution (pH 3.8)]. All of the tested antiulcer agents were applied simultaneously with cysteamine enema (8 cm from the anus, in a volume of the 1.0 ml/rat) intraperitoneally (i.p.), intragastrically (i.g.) or intrarectally (i.r.). Pentadecapeptide BPC 157 (10 microg or 10 ng/kg b.w.), given in either regimen, previously shown to have, besides others, a particular beneficial activity just in the intestinal mucosa, inhibited these cysteamine colon lesions (assessed after 30 min, 60 min, 180 min, 24 h, 48 h, 72 h following cysteamine in a dose of either 200 or 400 mg/kg i.r.). Cysteamine-colon lesions were also attenuated by standard antiulcer agents (mg/kg b.w.), given i.p., i.g., or i.r., such as ranitidine (10), cimetidine (50), omeprazole (10), atropine (10), together with methylprednisolone (1), and sulphasalazine (50, i.r.), assessed 30 min following application of 200 mg of cysteamine. Finally, standard cysteamine duodenal lesions (assessed 24 h after a subcutaneous application of 400 mg/kg of cysteamine) were also attenuated by these agents application (given in the same doses, i.p., 1 h before cysteamine), with only exception to sulphasalazine. Thus, the extended cysteamine specific ulcerogenic effect, cysteamine colon/duodenum lesion-link and an extenuation of agents protection from upper to lower part of gastrointestinal tract (i.e. stomach pentadecapeptide BPC 157, standard antiulcer agents, cimetidine, ranitidine, atropine, omeprazole) and vice versa (remedies for inflammatory bowel disease) evidenced in the present study may be potentially important for both further experimental and clinical research.

Portal hypertension and liver lesions in chronically alcohol drinking rats prevented and reversed by stable gastric pentadecapeptide BPC 157 (PL-10, PLD-116), and propranolol, but not ranitidine.

Liver lesions and portal hypertension in rats, following chronic alcohol administration, are a particular target for therapy. Portal hypertension (mm Hg) assessed directly into the portal vein, and liver lesions induced by 7.28 g/kg b.w. of alcohol given in drinking water for 3 months, were counteracted by a stable gastric pentadecapeptide BPC 157, GEPPPGKPADDAGLV, M.W. 1419, known to have a beneficial effect in a variety of models of gastrointestinal or liver lesions (10 microg or 10 ng/kg b.w. i.p. or i.g.) and propranolol (10 mg/kg b.w. i.g.), but not ranitidine (10 mg/kg b.w. i.g.) or saline (5 ml/kg b.w. i.p./i.g.; control). The medication (once daily) was throughout either the whole 3 months period (1) or the last month only (2) (last application 24 h before sacrifice). In the background of 7.28 g/kg/daily alcohol regimen similar lesions values were assessed in control rats following alcohol consumption, after 2 or 3 months of drinking. Both prophylactic and therapeutic effects were shown. After a period of 2 or 3 months, in all control saline [intragastrically (i.g.) or intraperitoneally (i.p.)] treated rats, the applied alcohol regimen consistently induced a significant rise of portal blood pressure values over values noted in healthy rats. In rats that received gastric pentadecapeptide BPC 157 or propranolol the otherwise raised portal pressure was reduced to the values noted in healthy rats. Besides, a raised surface area (microm(2)) and increased circumference (microm) of hepatocyte or hepatocyte nucleus [HE staining, measured using PC-compatible program ISSA (VAMS, Zagreb, Croatia)] and an advanced steatosis [scored (0-4), Oil Red staining] (on 100 randomly assigned hepatocytes per each liver), an increased liver weight, all together parallel a raised portal pressure in controls. Some of them were completely eliminated (not different from healthy rats, i.e. portal pressure, the circumference and area of hepatocytes, liver weight), while others were markedly attenuated (values less than in drinking controls, still higher than in healthy rats, i.e. circumference and area of hepatocytes nucleus). On the other hand, ranitidine application attenuated only steatosis development. In summary, despite continuous chronic alcohol drinking, pentadecapeptide BPC 157, and propranolol may prevent portal hypertension as well as reverse already established portal hypertension along with related liver disturbances.

Therapy effect of antiulcer agents on new chronic cysteamine colon lesion in rat.

After demonstration that cysteamine induced duodenal lesions in gastrectomized rats, while a number of antiulcer drugs mitigated these lesions, it was shown that one single intrarectal (i.r.) cysteamine application produced severe colon lesions in acute studies in rats. Thus, the further focus was on the protracted effect of cysteamine challenge (400 mg/kg b.w. i.r.) and therapy influence in chronic experiments in female rats. Regularly, cysteamine colon lesions were markedly mitigated by ranitidine (10), omeprazole (10), atropine (10), methylprednisolone (1), sulphasalazine (50; mg/kg), pentadecapeptide BPC 157 (PL-10, PLD-116; 10 microg or 10 ng/kg). Specifically, after 1 or 3 months following initial challenge (cysteamine 400 mg/kg i.r.) in female rat, the therapy [BPC 157 (PL-10, PLD-116 (10.0 microg or 10.0 ng/kg; i.g., i.p., i.r.), ranitidine, omeprazole, atropine, methylprednisolone, sulphasalazine (i.p.)] reversed the protracted cysteamine colon injury: the 1 week-regimen (once daily application) started after 1 month post-cysteamine, as well as the 2 weeks-regimen (once daily application), which started after 3 months. The effect on recidive lesion was also tested. These cysteamine lesions may reappear after stopping therapy (after stopping therapy for 3 weeks at the end of 2-weeks regimen started in 3 months-cysteamine female rats) in sulphasalazine group, while this reappearance is markedly antagonized in pentadecapeptide BPC 157 (PL-10, PLD-116)-rats (cysteamine-colon lesion still substantially low).

Chronic cytoprotection: pentadecapeptide BPC 157, ranitidine and propranolol prevent, attenuate and reverse the gastric lesions appearance in chronic alcohol drinking rats.

Unlike severe gastric damage acutely induced by ethanol administration in rat, the ulcerogenic effect of chronic alcohol administration (3.03 g/kg b.w. or 7.28 g/kg b.w.) given in drinking water, producing liver lesions and portal hypertension, is far less investigated. Therefore, focus was on the antiulcer effect of the gastric pentadecapeptide BPC 157, GEPPPGKPADDAGLV, M.W. 1419, known to have a beneficial effect in variety of gastrointestinal lesions models (10 microg or 10 ng/kg b.w. i.p. or i.g.), ranitidine (10 mg/kg b.w. i.g.) and propranol (10 mg/kg b.w. i.g.) or saline (5 ml/kg b.w. i.p./i.g.; control). They were given once daily (1) throughout 10 days preceding alcohol consumption, (2) since beginning of alcohol drinking till the end of the study, (3) throughout the last month of alcohol consumption, 2 months after alcohol drinking had been initiated. Gastric lesions were assessed, at the end of 3 months drinking [(1), (2)] or with respect to therapeutic effect of medication before medication or at the end of therapy. Pentadecapeptide BPC 157, ranitidine and propranolol may prevent gastric lesion development if given prophylactically, before alcohol drinking. Likewise, they attenuate the lesion appearance given once daily throughout the drinking period. Importantly, when given therapeutically, they may antagonize otherwise pertinent lesion presence in stomach mucosa of the drinking rats. Thus, these results demonstrate that pentadecapeptide BPC 157, ranitidine and propranol may prevent, attenuate or reverse the gastric lesions appearance in chronically alcohol drinking rats, and may be used for further therapy, while the other studies showed that their effect (except to ranitidine) is parallel with their beneficial effect on liver lesion and portal hypertension.

Gastric pentadecapeptide BPC 157 accelerates healing of transected rat Achilles tendon and in vitro stimulates tendocytes growth.

In studies intended to improve healing of transected Achilles tendon, effective was a stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, M.W. 1419). Currently in clinical trials for inflammatory bowel disease (PLD-116, PL 14736, Pliva), it ameliorates internal and external wound healing. In rats, the right Achilles tendon transected (5 mm proximal to its calcaneal insertion) presents with a large tendon defect between cut ends. Agents (/kg b.w., i.p., once time daily) (BPC 157 (dissolved in saline, with no carrier addition) (10 microg, 10 ng or 10 pg) or saline (5.0 ml)), were firstly applied at 30 min after surgery, the last application at 24 h before autopsy. Achilles functional index (AFI) was assessed once time daily. Biomechanical, microscopical and macroscopical assessment was on day 1, 4, 7, 10 and 14. Controls generally have severely compromised healing. In comparison, pentadecapeptide BPC 157 fully improves recovery: (i) biomechanically, increased load of failure, load of failure per area and Young's modulus of elasticity; (ii) functionally, significantly higher AFI-values; (iii) microscopically, more mononuclears and less granulocytes, superior formation of fibroblasts, reticulin and collagen; (iv) macroscopically, smaller size and depth of tendon defect, and subsequently the reestablishment of full tendon integrity. Likewise, unlike TGF-beta, pentadecapeptide BPC 157, presenting with no effect on the growth of cultured cell of its own, consistently opposed 4-hydroxynonenal (HNE), a negative modulator of the growth. HNE-effect is opposed in both combinations: BPC 157+HNE (HNE growth inhibiting effect reversed into growth stimulation of cultured tendocytes) and HNE+BPC 157(abolished inhibiting activity of the aldehyde), both in the presence of serum and serum deprived conditions. In conclusion, these findings, particularly, Achilles tendon transection fully recovered in rats, peptide stability suitable delivery, usefully favor gastric pentadecapeptide BPC 157 in future Achilles tendon therapy.

Corticosteroid-impairment of healing and gastric pentadecapeptide BPC-157 creams in burned mice.

The amelioration of corticosteroid-impairment of healing by a stable gastric pentadecapeptide BPC-157 (GEPPPGKPADDAGLV, M(w) 1419, currently in early clinical trials for inflammatory bowel disease) was studied in thermally injured mice. Its effects on corticosteroid impaired healing of deep partial skin thickness burns, and burn-gastric lesions were investigated. Male NMRI-Hannover mice (sacrificed at 1-3,7,14 and 21 days following burning 20% of total burn area at the back (open flame for 7s) received intraperitoneally (per kg bw) 6alpha-methylprednisolone (Depo-medrol, 1.0 or 10.0mg), or an equal volume of saline (5.0 ml), once daily, first application 30 min after injury, last 24h before sacrifice. The injury was subsequently treated by topical application of a thin layer of pentadecapeptide BPC-157 cream at three different levels a neutral cream of no treatment. Pentadecapeptide BPC-157 consistently improved given burn healing (both microscopical and tensionmetry assessment), and counteracted corticosteroid-impairment of burn healing. In burn-gastric lesions investigation of the effects of BPC showed an anti-ulcer effect of its own in burned non-corticosteroid-treated mice and potentiated the anti-ulcer effect observed in 6alpha-methylprednisolone-treated mice. Pentadecapeptide BPC-157 inhibited corticosteroid immunosuppression. In vitro, in spleenic cells assessment, animals (sacrificed at day 21) treated with 6alpha-methylprednisolone 1mg showed decreased reactivity to nitrogen in comparison with control, healthy animals, while the addition of BPC-157 (1 microg/g cream) returned cell reactivity to values noted in control healthy animals.

BPC 157 therapy to detriment sphincters failure-esophagitis-pancreatitis in rat and acute pancreatitis patients low sphincters pressure.

Possibly, acute esophagitis and pancreatitis cause each other, and we focused on sphincteric failure as the common causative key able to induce either esophagitis and acute pancreatitis or both of them, and thereby investigate the presence of a common therapy nominator. This may be an anti-ulcer pentadecapeptide BPC 157 (tested for inflammatory bowel disease, wound treatment) affecting esophagitis, lower esophageal and pyloric sphincters failure and acute pancreatitis (10 µg/kg, 10 ng/kg intraperitoneally or in drinking water). The esophagitis-sphincter failure procedure (i.e., insertion of the tubes into the sphincters, lower esophageal and pyloric) and acute pancreatitis procedure (i.e., bile duct ligation) were combined in rats. Esophageal manometry was done in acute pancreatitis patients. In rats acute pancreatitis procedure produced also esophagitis and both sphincter failure, decreased pressure 24 h post-surgery. Furthermore, bile duct ligation alone immediately declines the pressure in both sphincters. Vice versa, the esophagitis-sphincter failure procedure alone produced acute pancreatitis. What's more, these lesions (esophagitis, sphincter failure, acute pancreatitis when combined) aggravate each other (tubes into sphincters and ligated bile duct). Counteraction occurred by BPC 157 therapies. In acute pancreatitis patients lower pressure at rest was in both esophageal sphincters in acute pancreatitis patients. We conclude that BPC 157 could cure esophagitis/sphincter/acute pancreatitis healing failure.

High hepatotoxic dose of paracetamol produces generalized convulsions and brain damage in rats. A counteraction with the stable gastric pentadecapeptide BPC 157 (PL 14736).

We focused on stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, MW 1419, an anti-ulcer peptide efficient in inflammatory bowel disease trials (PL 14736), no toxicity reported) because of its hepatoprotective effects. We investigate a particular aspect of the sudden onset of encephalopathy with extreme paracetamol overdose (5 g/kg intraperitoneally) so far not reported: rapidly induced progressive hepatic encephalopathy with generalized convulsions in rats. BPC 157 therapy (10 microg, 10 ng, 10 pg/kg, intraperitoneally or intragastrically) was effective (microg-ng range) against paracetamol toxicity, given in early (BPC 157 immediately after paracetamol, prophylactically) or advanced stage (BPC 157 at 3 hours after paracetamol, therapeutically). At 25 min post-paracetamol increased ALT, AST and ammonium serum values precede liver lesion while in several brain areas, significant damage became apparent, accompanied by generalized convulsions. Through the next 5 hour seizure period and thereafter, the brain damage, liver damage enzyme values and hyperammonemia increased, particularly throughout the 3-24 h post-paracetamol period. BPC 157 demonstrated clinical (no convulsions (prophylactic application) or convulsions rapidly disappeared (therapeutic effect within 25 min)), microscopical (markedly less liver and brain lesions) and biochemical (enzyme and ammonium serum levels decreased) counteraction. Both, the prophylactic and therapeutic benefits (intraperitoneally and intragastrically) clearly imply BPC 157 (microg-ng range) as a highly effective paracetamol antidote even against highly advanced damaging processes induced by an extreme paracetamol over-dose.

Gastric pentadecapeptide BPC 157 counteracts morphine-induced analgesia in mice.

Previously, the gastric pentadecapeptide BPC 157, (PL 14736, Pliva) has been shown to have several beneficial effects, it exert gastroprotective, anti-inflammatory actions, stimulates would healing and has therapeutic value in inflammatory bowel disease. The present study aimed to study the effect of naloxone and BPC 157 on morphine-induced antinociceptive action in hot plate test in the mouse. It was found that naloxone and BPC 157 counteracted the morphine (16 mg/kg s.c.) - analgesia. Naloxone (10 mg/kg s.c.) immediately antagonised the analgesic action and the reaction time returned to the basic values, the development of BPC 157-induced action (10 pg/kg, 10 ng/kg, 10 microg/kg i.p.) required 30 minutes. When haloperidol, a central dopamine-antagonist (1 mg/kg i.p.), enhanced morphine-analgesia, BPC 157 counteracted this enhancement and naloxone reestablished the basic values of pain reaction. BPC 157, naloxone, and haloperidol per se failed to exert analgesic action. In summary, interaction between dopamine-opioid systems was demonstrated in analgesia, BPC 157 counteracted the haloperidol-induced enhancement of the antinociceptive action of morphine, indicating that BPC acts mainly through the central dopaminergic system.