Establishment of Patient-derived Preclinical Models for Invasive Papillary Cholangiocarcinoma

BACKGROUND/AIM

Invasive papillary cholangio-carcinoma (IPC) is a minor subtype of extrahepatic cholangiocarcinoma. However, its etiology and characteristics remain unknown because of the unavailability of in vitro and in vivo models. We aimed to establish a novel preclinical model for translational research of IPC.

MATERIALS AND METHODS

A patient-derived xenograft (PDX) was engrafted in NOG mice and the cell line National Cancer Center human IPC (NCChIPC) was subsequently established from the PDX tumors. Immunohistochemistry and RNA-sequencing were used to determine the retention of original characteristics of patient tissues.

RESULTS

PDX tumors showed successful amplification, and the NCChIPC-derived xenograft largely retained the histopathological features of the original tumor with CK19, MUC1 and MUC5AC expression. Transcriptome analysis showed a high correlation between patient and preclinical models. Additionally, anticancer drugs response was analyzed in the NCChIPC PDX.

CONCLUSION

These novel preclinical models here will help elucidate IPC etiology and facilitate translational research.

Development of Patient-Derived Preclinical Platform for Metastatic Pancreatic Cancer: PDOX and a Subsequent Organoid Model System Using Percutaneous Biopsy Samples

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal malignant tumor and more than 50% patients are diagnosed at metastatic stage. The preclinical model systems that reflect the genetic heterogeneity of metastatic tumors are urgently needed to guide optimal treatment. This study describes the development of patient-derived preclinical platform using very small sized-percutaneous liver gun biopsy (PLB) of metastatic pancreatic cancer, based on patient-derived xenograft (PDX)-mediated tissue amplification and subsequent organoid generation. To increase the success rate and shorten the tumor growth period, patient-derived orthotopic xenograft (PDOX) model was developed to directly implant threadlike PLB samples into the pancreas. The engraftment success rate of PDOX samples from 35 patients with metastatic PDAC was 47%, with these samples showing the potential to metastasize to distant organs, as in patients. The PDOX models retained the genetic alterations and histopathological features of the primary tumors. Tumor organoids were subsequently generated from first passage cancer cells isolated from F1 tumor tissue of PDOX that preserve the epithelial cancer characteristics and KRAS mutations of primary tumors. The response to gemcitabine of PDOX-derived organoids correlated with clinical outcomes in corresponding patients as well as PDOX models in vivo, suggesting that this PDOX-organoid system reflects clinical conditions. Collectively, these findings indicate that the proposed PDOX-organoid platform using PLB samples assessed both in vitro and in vivo could predict drug response under conditions closer to those found in actual patients, as well as enhancing understanding of the complexity of metastatic PDAC.

Aberrant Crypt Foci in the Background Mucosa of Colorectal Adenocarcinoma

PURPOSE

This study was performed in order to determine the histologic features, incidence & frequency of the Aberrant Crypt Foci (ACFs) including mucosal abnormalities arising in the sporadic colonic cancer.

MATERIALS AND METHODS

We investigated the proximal and distal colonic mucosa surrounding the tumor in 22 cases (right colon 7 cases and left colon 15 cases) of resected colonic adenocarcinoma specimen. The methylene blue- stained colonic mucosa was examined in en face preparations and rolled totally. The rolled colonic mucosa was embedded in paraffin and examined by using 4micrometer thick serial sections.

RESULTS

We found one hundred twenty two ACFs. The 97 foci (78.7%) were simple hypertrophic foci (SH), composed of more elongated and larger crypts than normal with apical branching associated with goblet cell hyperplasia. The 17 foci (13.9%) were hyperplastic foci (HP) resembling hyperplastic polyp, and 7 (5.7%) were adeno matous foci (AD) while 2 (1.6%) were adenomatous foci with dysplasia (Dys). The mean number of ACFs/cm of the examined mucosa were 0.18+/-0.21 and were higher in the left colon than in the right colon (0.22+/-0.24 vs. 0.10+/-0.10). Immunohistochemical stains for p53 and Ki-67 in these foci revealed strong and upper cryptal staining patterns in AD and Dys of ACFs, like that of neoplasia or preneoplastic condition. However, the staining intensities in SH and HP of ACFs were equal to or lower than that of normal crypts.

CONCLUSION

These results suggest that grossly defined ACFs include reactive process and the majority of ACFs are induced by simple reactive alteration without preneoplastic potential; and two types of ACFs (AD and Dys) are more likely to be direct precursors of colon tumors than SH or HP.

T-category reflects the histopathologic characteristics of gallbladder cancer

AIMS

Gallbladder (GB) cancer is a relatively uncommon gastrointestinal malignancy and is known to often result in unfavorable outcomes. Recent advances in aggressive surgical resection have improved the overall survival rate of patients with GB cancer. We aimed to evaluate the outcomes and prognostic factors of GB cancer following a surgical resection with curative intent.

METHODS

Between March 2001 and March 2009, 89 patients with GB cancer underwent surgical resection with curative intent at the National Cancer Center of Korea. We then conducted a retrospective analysis of clinicopathologic data.

RESULTS

Nineteen patients underwent simple cholecystectomy and 70 patients underwent extended cholecystectomy. Tumor-free resection margins were obtained in 84 cases. The 1-, 3- and 5-year disease-specific survival rates in the 89 patients were 85.8%, 68.0% and 64.1%, respectively. By multivariate analysis, only the T-category was significant (p < 0.001). The T-category showed a close correlation with all of the other histopathologic factors which were significant in univariate analysis.

CONCLUSION

The T-category of GB cancer represents not only the depth of the primary tumor but also the aggressiveness of its histopathologic nature.

Comparative study of the subserosal versus submucosal dye injection method for sentinel node biopsy in gastric cancer

AIMS

To determine the most efficient injection method for a sentinel node (SN) biopsy in gastric cancer.

METHODS

Gastric adenocarcinoma patients without serosal invasion and distant metastasis were prospectively enrolled in this study. Isosulfan blue was injected into the subserosa (SS) of the first set of 71 consecutive patients and an intraoperative endoscopic submucosal (SM) injection of the same dye was injected into the second set of 50 consecutive patients. After the biopsy of blue-stained SNs, a gastrectomy with a D2 lymphadenectomy was performed. All dissected lymph nodes were evaluated for metastasis. The results of the SN biopsies were compared between the SS and SM dye injection methods.

RESULTS

Detection rate (0.92 vs 0.94), mean number of SNs (2.5 vs 2.9) and sensitivity (0.61 vs 0.46) of the SN biopsies were not significantly different between the SS and SM injection methods (P>0.05). The operation time was significantly shorter in the SS than the SM injection method (159.7 vs 172.7 min, P=0.030).

CONCLUSIONS

Both injection methods were equally efficient in their roles for a SN biopsy in gastric cancer. However, the SS injection method was more preferable due to its easy technique and short operation time.

Thymidine phosphorylase expression in tumour cells and tumour response to capecitabine plus docetaxel chemotherapy in non-small cell lung cancer

BACKGROUND

Thymidine phosphorylase (TP) is the key enzyme for capecitabine activation in tumour cells.

AIMS

To examine whether TP expression in tumour cells and stroma is predictive of the tumour response to capecitabine plus docetaxel chemotherapy in patients with advanced non-small cell lung cancer (NSCLC).

METHODS

Tumour samples were available from 30 of 39 patients enrolled in a previous phase II study of capecitabine/docetaxel chemotherapy in patients with advanced NSCLC. Stromal and tumour cell TP expression was evaluated by immunohistochemistry using monoclonal antibody PD-ECGF.

RESULTS

High tumour cell TP expression was found in 13 of 30 cases and was negatively associated with stromal TP expression (p = 0.000). High stromal TP expression was found in 16 of 28 cases and was strongly associated with intense macrophage infiltration (p = 0.002), suggesting that macrophages are the major component of TP expression in the stroma. Tumour response to capecitabine/docetaxel was significantly associated with high tumour cell TP expression (p = 0.004) and low stromal TP expression (p = 0.009). Moreover, high tumour cell TP expression was significantly associated with severe hand-foot syndrome, a toxic side effect of capecitabine (p = 0.01). Improved survival was seen for high tumour cell and low stromal TP expression, although results were not significant (p = 0.6 and 0.3, respectively).

CONCLUSIONS

In advanced NSCLC, TP expression in tumour cells and stroma is associated with tumour response to capecitabine/docetaxel chemotherapy, and might be a useful predictor of tumour response to capecitabine based chemotherapy. A large scale prospective study is needed to confirm the prognostic significance of TP expression in NSCLC.

Idiopathic multilocular thymic cyst: CT features with clinical and histopathologic correlation

OBJECTIVE

We performed this study to describe the CT features of idiopathic multilocular thymic cysts with clinical and histopathologic correlation.

CONCLUSION

Multilocular thymic cysts typically manifest on CT as unilocular or multilocular cystic thymic masses, often with soft-tissue attenuation components. CT cannot be used to distinguish neoplastic from nonneoplastic soft-tissue components.

Two imported cases of cutaneous larva migrans

Cutaneous larva migrans (CLM) is a rare serpiginous cutaneous eruption caused by accidental penetration and migration in the skin with infective larvae of nematode that normally do not have the human as their host. Although CLM has a worldwide distribution, the infection is most frequent in warmer climates. More recently, they have been increasingly imported from the tropics or subtropics by travelers. We experienced two patients who had pruritic serpiginous linear eruption in their skin for a few weeks after traveling to the endemic areas (Brazil and Thailand, respectively). After the treatment with albendazole, the skin lesions resolved with post-inflammatory hyperpigmentation. We report herein two cases of cutaneous larva migrans successfully treated with albendazole.

Water extract of 1:1 mixture of Phellodendron cortex and Aralia cortex has inhibitory effects on oxidative stress in kidney of diabetic rats

Enhanced activity of the lipid peroxidation and oxidative damages have been implicated in the pathogenesis of diabetic kidney complications. We explored to determine whether these changes in diabetic kidney could be prevented by water extract of mixture of Phellodendron cortex and Aralia cortex (P55A). Greatly elevated content of thiobarbituric acid reactive substances (TBARS) and carbonylated protein in kidneys of diabetic rats were significantly reduced by P55A treatment. In addition, abnormally low ratio of GSH/GSSG in diabetic kidneys was elevated to almost normal levels by the treatment with P55A. These results suggest that P55A extracts exert antioxidant effect by reducing lipid peroxidation and protein carbonylation as well as by elevating the ratio of GSF/GSSG in diabetic kidney.

Expression of tenascin-C in astrocytic tumors: its relevance to proliferation and angiogenesis

BACKGROUND

The expression and distribution of the extracellular matrix protein tenascin-C (TN-C) may be enhanced in human astrocytomas. The purpose of this study is to evaluate the expression of TN-C according to histological malignancy of tumor cells and its relevance to neoplastic angiogenesis in human astrocytic tumors.

METHODS

Between 1994 and 1998, 52 astrocytic tumor specimens including 4 pilocytic astrocytomas, 13 astrocytomas, 3 anaplastic astrocytomas, and 32 glioblastomas were used in this study. A retrospective analysis was performed to evaluate a statistical correlation between TN-C expression and proliferative indices. We characterized the expression of TN-C in neoplastic vessels, around individual tumor cells as a tumor network, and in tumor cells by immunohistochemistry using antibodies against human TN-C. The proliferative indices were also investigated by immunostaining with the MIB-1 antibody against the Ki-67 proliferation antigen.

RESULTS

TN-C immunoreactivity was found to be enhanced in tumor vessels and tumor networks of high-grade astrocytic tumors. The vascular TN-C deposition was greater in high-grade than in low-grade astrocytic tumors (p < 0.05). Its expression was the most intense in glioblastomas. Proliferation indices increased with tumor grade and MIB-1 labeling index (LI) was highest in glioblastomas. Moreover, expression of TN-C in tumor vessels was correlated with proliferative indices.

CONCLUSIONS

Our data show that TN-C in human astrocytic tumors may be identified as a factor contributing to malignant progression. And also, enhanced expression of TN-C in tumor vessels having a high proliferative index indicates that TN-C could be involved in neoplastic angiogenesis.

Posterior tibial neuropathy by a Baker's cyst: case report

Baker's cysts are rare cause of peripheral nerve entrapment and only a few cases of tibial nerve entrapment resulting from the popliteal cyst in the calf muscle have been reported in the literature. We present a case of rheumatoid arthritis complicated by a Baker's cyst with a tibial nerve entrapment. It is important to diagnose a Baker's cyst early and to differentiate it from thrombophlebitis, a popliteal aneurysm, tumor or muscle tear to effect optimal therapy and to obviate a potential neuropathy. Prompt recognition of these cases may save the patients unnecessary procedures and delay in treatment.

Time dependent patient satisfaction with sildenafil for erectile dysfunction (ED) after nerve-sparing radical retropubic prostatectomy (RRP)

PURPOSE

The response to sildenafil after radical retropubic prostatectomy (RRP) has been reported to be approximately 40% by the Sildenafil Study Group. We undertook a study in a large cohort of post-RRP erectile dysfunction (ED) patients in order to examine the relationship between satisfaction with sildenafil and time from surgery to start of sildenafil treatment.

METHODS

Pre- and post-operative erectile function was assessed by the O'Leary Brief Sexual Function Inventory questionnaire. Patient satisfaction with sildenafil before and after sildenafil treatment was assessed by the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) questionnaire. Between April and October 1998, EDITS questionnaires were given to 579 patients who had undergone RRP between 1994 and 1998. 316 (55%) patients returned questionnaires. Of these, 198 (63%) had sildenafil treatment and completed post-treatment questionnaires and were included in the study group.

RESULTS

In the study group, mean age was 61y. Pre-operatively, 92% had erections sufficient for vaginal penetration, 95% had bilateral nerve-sparing (NS) RRP. There was a significant increase in the treatment satisfaction rate with increasing time from surgery. Between zero and six months after surgery, the treatment satisfaction rate was 26%, which improved with time, peaking at 60% between 18 months and 2y. Self-perceived erectile function as determined by post-RRP pre-sildenafil treatment O'Leary questionnaires was not as predictive of response to sildenafil as time from surgery.

CONCLUSIONS

The response to sildenafil appears to be dependent upon the interval between RRP and the start of sildenafil. The treatment satisfaction rate was found to peak at 60% between 18 months and 2y. Early nonresponders to sildenafil should not be disheartened, as they will more likely later respond.

Expression of cyclin D1 and cyclin E in human gastric carcinoma and its clinicopathologic significance

Cyclin D1 and cyclin E are the mammalian G1 cydins that are both required and rate limiting for entry into S phase. Alterations in cell cycle regulators and subsequent deregulation of the cell cycle are frequently involved in tumorigenesis and/or tumor progression. We investigated the expression of cyclin D1 and cyclin E protein in 84 gastric carcinoma by immunohistochemical staining and also the relevance of each cyclin expression to the clinical outcomes. Overexpression of cyclin D1 and cyclin E was noted in 21 of 84 (25.0%) and 34 of 84 (40.5%) gastric cancer tissues, respectively. There was a significant correlation between overexpression of cyclin E and lymph node metastasis (p=0.003), recurrence (p=0.043), disease free survival (p=0.0378) and overall survival (p=0.0319), but no correlation was noted between overexpression of cyclin D1 and other clinicopathologic variables. These findings suggest that overexpression of cyclin E and cyclin D1 is a frequent finding in gastric cancer and immunohistochemical analysis for cell cycle regulators, especially cyclin E might be a useful prognostic indicator in gastric cancer.

Eosinophil-induced chronic hepatitis

Chronic hepatitis associated with hypereosinophilia has been very rarely reported worldwide. A 7-month-old male infant presented with a high fever, cough, non-projectile vomiting and hepatomegaly. The eosinophil count of the peripheral blood increased up to 21,500/mm3 (49% of WBC). The infant had a history of frequent contact with a neighbor keeping a pigsty. The pathologic examinations of the liver showed severe porto-periportal necroinflammation with marked eosinophilic infiltration, giant cell transformation and ballooning degeneration of hepatocytes, and degranulation of the eosinophils. Bone marrow showed increased eosinophils and decreased myeloid series. Pericardial effusion and bilateral pulmonary consolidation were noted. Corticosteroid aggravated the clinical symptoms of the infant. Anthelmintic treatment significantly normalized the eosinophil count and liver function tests, but cardiopulmonary manifestations continued.

Poorly differentiated ("insular") carcinoma of the thyroid gland--two cases report

Poorly differentiated ("insular") carcinoma of the thyroid shares insular, trabecular, and solid histological patterns that are different from those of papillary, follicular, medullary, and anaplastic varieties. This tumor is situated morphologically and biologically in the intermediate position between the well differentiated (papillary and follicular) and the totally undifferentiated (anaplastic) thyroid tumors. We report two cases of insular carcinoma of the thyroid, occurring in 39-year-old and 52-year-old women. Grossly, these cases showed a lobulated mass with fibrous septa. The histologic finding showed characteristic "insular" growth pattern with focal follicular or papillary areas. Thyroglobulin was demonstrated within cytoplasmic paranuclear vacuoles of the neoplastic cells. Calcitonin and amyloid were not demonstrated. The aspiration cytology showed high cellularity, low grade of atypia, presence of clusters, nests, and trabeculae of cells with poorly outlined cytoplasm. The ultrastructural finding showed primordial cells having cytoplasmic organelles such as rough endoplasmic reticulum, mitochondria, and free ribosomes. We believe that its separation from other types of thyroid carcinoma will lead to a more accurate estimate of its biologic behavior and a more appropriate therapeutic approach.

Enhanced anti-tumour effects of acriflavine in combination with guanosine in mice

The anti-tumour activity of acriflavine in combination with guanosine has been evaluated in solid or ascitic tumour-implanted animal models. Guanosine is known to potentiate the anti-tumour effects of some chemotherapeutic agents. Administration of acriflavine (15 mg kg-1 day-1, i.m., 14 days) to ICR mice subcutaneously implanted with Ehrlich carcinoma resulted in approximately 30% inhibition in tumour growth. In contrast, minor tumour growth inhibition was observed in animals treated with guanosine at the same daily dose. Treatment of animals with both acriflavine and guanosine (AG60, 1:1, w/w) at 30 mg kg-1 resulted in approximately 65% inhibition in tumour growth rate. Whereas treatment with acriflavine or guanosine resulted in 70% or 30% decrease in tumour weight, respectively, treatment of tumour-implanted mice with AG60 (30 mg kg-1) resulted in a 96% decrease in tumour weight, relative to control, 14 days after tumour-cell implantation. Dose-related inhibition in tumour growth rate was also observed in animals treated with AG60, with maximum (65%) inhibition noted at a dose of 30 mg kg-1 (ED50 23 mg kg-1). Suppression of body weight increase and elevated plasma glucose levels by acriflavine or AG60 indicated that glucose utilization might be impaired. The anti-tumour effect of AG60 was also determined in CDF1 mice intraperitoneally implanted with Ehrlich ascitic tumour. Ehrlich ascitic tumour proliferation was completely suppressed by AG60 (30 mg kg-1, i.p.). Microscopic analyses of intraperitoneal touch-prints revealed that AG60 was more effective in suppressing tumour proliferation than acriflavine alone. Fluorescent microscopic examinations demonstrated that acriflavine avidly bound with Yac-1 cell plasma membrane, leading to morphological changes in the cells, such as bleb formations, swelling and ballooning. The time-related changes in tumour cell morphology by acriflavine or AG60 might represent energy depletion, followed by osmotic lysis as a result of cationic influx. Enhanced anti-tumour activity of acriflavine in combination with guanosine might be explained by the blocking of nutrient transport through selective acriflavine binding with plasma membrane and by concomitant guanosine perturbation of cellular ATP production. This study demonstrates that guanosine enhances the anti-tumour effects of acriflavine against a variety of cancer cells without serious adverse effects, providing a preclinical basis for potential application of this combination against cancer proliferation.

Microcystic meningioma. A case report

Microcystic meningioma is a distinct morphological variant of meningioma, characterized by loose texture and microcysts with formation of large extracellular spaces containing edematous fluid. The tumor cells have stellate and vacuolated cytoplasm with long cytoplasmic processes. We experienced a case of typical microcystic meningioma occurring in the falx cerebri adjacent to the left superior parasagittal sinus in a 41-year-old man. The tumor showed the typical histologic features with a few nests of meningothelial whorls. The tumor cells showed diffuse immunoreactivity for vimentin, epithelial membrane antigen (EMA), and S-100 protein. Ultrastructural study confirmed the meningiomatous nature of the tumor.

Atretic encephalocele/myelocele--case reports with emphasis on pathogenesis

Atretic encephaloceles or myelomeningoceles are frequently solid due to hamartomatous proliferation of fibrous tissue and blood vessels. Because of the fibrous nature of the tumor with no cystic cavity and unusual location with no connection to CNS, they are frequently regarded as insignificant hamartomas. Apart from this terminology, they are also described as cutaneous meningiomas or hamartomas with ectopic meningothelial elements by the presence of meningothelial cells. We report a case of atretic encephalocele in the parietal scalp of an 8 year-old boy and a case of myelomeningocele in the posterior mediastinum of a 31 year-old woman. The terms atretic encephalocele and myelomeningocele are more appropriate for these cases because they include their pathogenesis and the non-neoplastic nature of the lesion.

A case of Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is presumably caused by a slow infectious pathogen or prion. The principal clinical features of Creutzfeldt-Jakob disease are dementia, pyramidal and extrapyramidal symptoms and signs, cerebellar dysfunction, and myoclonus. The patient rapidly deteriorates, declines to a vegetative state, becomes comatous, and is ultimately dead within several months. The authors present a case of Creutzfeldt-Jakob disease, proved by clinical findings, typical serial EEG, and pathologic features.

Fibrous hamartoma of infancy manifested as multiple nodules--a case report

Fibrous hamartoma of infancy is an uncommon benign fibrous proliferation, usually presenting as a solitary nodule. A rare example of multiple fibrous hamartoma of infancy is described. Two masses which developed in the upper arm of a 10-month-old boy were successfully excised, and one month later three small nodules 2 cm below the previous operation field appeared. It will be further elucidated whether multiple forms and early recurrence are related or not as cases accumulate.

A national study on biopsy-confirmed thyroid diseases among Koreans: an analysis of 7758 cases

In order to determine the incidence and to understand recent trend of thyroid neoplasm and other thyroid diseases among Korean, a nation-wide collection of biopsy-confirmed and surgically removed thyroid lesions from 30 pathology laboratories of university and general hospitals was made over a 3-year-period from 1986 to 1988. These tumors and tumor-like lesions of the thyroid were classified according to the WHO classification. Results of this study were compared with those of the previous in Korea and other countries. Among the 7758 collected cases from 7449 patients, adenomatous goiter was the most common, comprising 2681 cases (34.6%), followed by follicular adenoma, 1868 cases (24.1%) and papillary carcinoma, 1474 cases (19%). Neoplastic condition comprised 48.8% (3786 cases). Of malignant tumors, papillary carcinoma was the most frequent accounting for 79.8%. The female to male ratio was 7.5:1 with female predominance. This female predominance was noted in all but two thyroid diseases. Medullary carcinoma showed equal distribution in both sexes, and two cases of malignant lymphoma developed in males. Thyroid diseases were common at the 3rd to 6th decades with peak incidence at the 4th decade. The right lobe of the thyroid was more frequently involved than the left lobe (1.6:1). The diagnoses were made largely on the surgically excised specimen (85.3%). Multiplicity of the lesions revealed single lesion in 64%, multiple and diffuse lesion in 36% of cases investigated. Average size of the lesion was in the range of 1-5 cm in diameter (62%).

Indirect involvement of delta opioid receptors in cholecystokinin octapeptide-induced analgesia in mice

Sulfated cholecystokinin octapeptide (CCK-8; Asp-Tyr-SO3H-Met-Gly-Trp-Met-Asp-Phe-NH2) produced analgesia in mice when administered i.c.v. and tested in the acetic acid-induced writhing assay. The ED50 was found to be 0.03 nmol/mouse which was about 3, 24 and 714 times more potent than morphine. [D-Pen2,D-Pen5]enkephalin and U50,488H [trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrolidinyl)cyclohexyl] benzeneacetamidel], respectively. When administered i.t., CCK-8 produced partial analgesia of up to 22 to 23% at low doses ranging from 15 to 60 ng/mouse and hyperalgesia at doses over 120 ng/mouse. Naloxone, an opioid antagonist, inhibited the analgesia induced by CCK-8 (i.c.v. and i.t.) but potentiated hyperalgesia induced by CCK-8 (i.t.). Apparent pA2 value for CCK-8 (i.c.v.) against naloxone (s.c.) was 5.88 which was significantly different from those for morphine-naloxone and U50,488H-naloxone but was not significantly different from that for [D-Pen2,D-Pen5]enkephalin-naloxone. Studies using highly selective opioid antagonists showed that CCK-8-induced analgesia was significantly antagonized by the delta receptor antagonist, ICI154,129 [(Allyl)2-Tyr-gly-gly-psi-(CH2S)-Phe-Leu] but not by beta-funaltrexamine, a highly selective mu receptor antagonist or nor-binaltorphimine, a highly selective kappa receptor antagonist. Opioid receptor binding study using [3H]-[D-Ala2,D-Leu5]enkephalin (+unlabeled [D-Ala2,MePhe4,Gly-ol5]enkephalin) in mouse brain membrane preparations revealed that there were no changes in the maximum binding or Kd of delta opioid binding sites in the presence of CCK-8 (1 microM) in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)