A systematic review and meta-analysis of germline BRCA mutations in pancreatic cancer patients identifies global and racial disparities in access to genetic testing.

BACKGROUND: Germline BRCA1 and BRCA2 mutations (gBRCAm) can inform pancreatic cancer (PC) risk and treatment but most of the available information is derived from white patients. The ethnic and geographic variability of gBRCAm prevalence and of germline BRCA (gBRCA) testing uptake in PC globally is largely unknown. MATERIALS AND METHODS: We carried out a systematic review and prevalence meta-analysis of gBRCA testing and gBRCAm prevalence in PC patients stratified by ethnicity. The main outcome was the distribution of gBRCA testing uptake across diverse populations worldwide. Secondary outcomes included: geographic distribution of gBRCA testing uptake, temporal analysis of gBRCA testing uptake in ethnic groups, and pooled proportion of gBRCAm stratified by ethnicity. The study is listed under PROSPERO registration number #CRD42022311769. RESULTS: A total of 51 studies with 16 621 patients were included. Twelve of the studies (23.5%) enrolled white patients only, 10 Asians only (19.6%), and 29 (56.9%) included mixed populations. The pooled prevalence of white, Asian, African American, and Hispanic patients tested per study was 88.7%, 34.8%, 3.6%, and 5.2%, respectively. The majority of included studies were from high-income countries (HICs) (64; 91.2%). Temporal analysis showed a significant increase only in white and Asians patients tested from 2000 to present (P < 0.001). The pooled prevalence of gBRCAm was: 3.3% in white, 1.7% in Asian, and negligible (<0.3%) in African American and Hispanic patients. CONCLUSIONS: Data on gBRCA testing and gBRCAm in PC derive mostly from white patients and from HICs. This limits the interpretation of gBRCAm for treating PC across diverse populations and implies substantial global and racial disparities in access to BRCA testing in PC.

SOX2 promotes dedifferentiation and imparts stem cell-like features to pancreatic cancer cells.

SOX2 (Sex-determining region Y (SRY)-Box2) has important functions during embryonic development and is involved in cancer stem cell (CSC) maintenance, in which it impairs cell growth and tumorigenicity. However, the function of SOX2 in pancreatic cancer cells is unclear. The objective of this study was to analyze SOX2 expression in human pancreatic tumors and determine the role of SOX2 in pancreatic cancer cells regulating CSC properties. In this report, we show that SOX2 is not expressed in normal pancreatic acinar or ductal cells. However, ectopic expression of SOX2 is observed in 19.3% of human pancreatic tumors. SOX2 knockdown in pancreatic cancer cells results in cell growth inhibition via cell cycle arrest associated with p21(Cip1) and p27(Kip1) induction, whereas SOX2 overexpression promotes S-phase entry and cell proliferation associated with cyclin D3 induction. SOX2 expression is associated with increased levels of the pancreatic CSC markers ALDH1, ESA and CD44. Importantly, we show that SOX2 is enriched in the ESA(+)/CD44(+) CSC population from two different patient samples. Moreover, we show that SOX2 directly binds to the Snail, Slug and Twist promoters, leading to a loss of E-Cadherin and ZO-1 expression. Taken together, our findings show that SOX2 is aberrantly expressed in pancreatic cancer and contributes to cell proliferation and stemness/dedifferentiation through the regulation of a set of genes controlling G1/S transition and epithelial-to-mesenchymal transition (EMT) phenotype, suggesting that targeting SOX2-positive cancer cells could be a promising therapeutic strategy.

Mesenteric venous collateral vessels mimicking cystic pancreatic neoplasm.

We report an unusual case of intrapancreatic mesenteric venous collateral vessels following partial pancreatic surgical resection resembling pancreatic neoplasm upon greyscale sonographic and unenhanced CT examinations.

Risk of malignancy in resected cystic tumors of the pancreas < or =3 cm in size: is it safe to observe asymptomatic patients? A multi-institutional report.

Recent international consensus guidelines propose that cystic pancreatic tumors less than 3 cm in size in asymptomatic patients with no radiographic features concerning for malignancy are safe to observe; however, there is little published data to support this recommendation. The purpose of this study was to determine the prevalence of malignancy in this group of patients using pancreatic resection databases from five high-volume pancreatic centers to assess the appropriateness of these guidelines. All pancreatic resections performed for cystic neoplasms < or =3 cm in size were evaluated over the time period of 1998-2006. One hundred sixty-six cases were identified, and the clinical, radiographic, and pathological data were reviewed. The correlation with age, gender, and symptoms (abdominal pain, nausea and vomiting, jaundice, presence of pancreatitis, unexplained weight loss, and anorexia), radiographic features suggestive of malignancy by either computed tomography, magnetic resonance imaging, or endoscopic ultrasound (presence of solid component, lymphadenopathy, or dilated main pancreatic duct or common bile duct), and the presence of malignancy was assessed using univariate and multivariate analysis. Among the 166 pancreatic resections for cystic pancreatic tumors < or =3 cm, 135 cases were benign [38 serous cystadenomas, 35 mucinous cystic neoplasms, 60 intraductal papillary mucinous neoplasms (IPMN), 1 cystic papillary tumor, and 1 cystic islet cell tumor], whereas 31 cases were malignant (14 mucinous cystic adenocarcinomas and 13 invasive carcinomas and 4 in situ carcinomas arising in the setting of IPMN). A greater incidence of cystic neoplasms was seen in female patients (99/166, 60%). Gender was a predictor of malignant pathology, with male patients having a higher incidence of malignancy (19/67, 28%) compared to female patients (12/99, 12%; p < 0.02). Older age was associated with malignancy (mean age 67 years in patients with malignant disease vs 62 years in patients with benign lesions (p < 0.05). A majority of the patients with malignancy were symptomatic (28/31, 90%). Symptoms that correlated with malignancy included jaundice (p < 0.001), weight loss (p < 0.003), and anorexia (p < 0.05). Radiographic features that correlated with malignancy were presence of a solid component (p < 0.0001), main pancreatic duct dilation (p = 0.002), common bile duct dilation (p < 0.001), and lymphadenopathy (p < 0.002). Twenty-seven of 31(87%) patients with malignant lesions had at least one radiographic feature concerning for malignancy. Forty-five patients (27%) were identified as having asymptomatic cystic neoplasms. All but three (6.6%) of the patients in this group had benign disease. Of the patients that had no symptoms and no radiographic features, 1 out of 30 (3.3%) had malignancy (carcinoma in situ arising in a side branch IPMN). Malignancy in cystic neoplasms < or =3 cm in size was associated with older age, male gender, presence of symptoms (jaundice, weight loss, and anorexia), and presence of concerning radiographic features (solid component, main pancreatic duct dilation, common bile duct dilation, and lymphadenopathy). Among asymptomatic patients that displayed no discernable radiographic features suggestive of malignancy who underwent resection, the incidence of occult malignancy was 3.3%. This study suggests that a group of patients with small cystic pancreatic neoplasms who have low risk of malignancy can be identified, and selective resection of these lesions may be appropriate.

Doctor-patient communication in surgery: attitudes and expectations of general surgery patients about the involvement and education of surgical residents.

BACKGROUND: Education is a major function of academic medical centers. At these teaching institutions residents provide a substantial amount of care on medical and surgical services. The attitudes of patients about the training of surgical residents and the impact of residents on patients' perceptions of care in a surgical setting are unknown. STUDY DESIGN: Patients admitted to the gastrointestinal surgery service completed a 30-item survey designed for this study. Patients included in the study underwent operations and had a postoperative inpatient hospital stay. We analyzed patients' answers to determine frequency and correlations among answers. RESULTS: Two hundred patients participated in the study during a 7-month period between July 1999 and January 2000. A majority of patients were comfortable having residents involved in their care (86%) and felt it was important to help educate future surgeons (91%). Most did not feel inconvenienced by being at a teaching hospital (71%) and felt they received extra attention there (74%). Patients were more willing to participate in resident education if they expected to have several physicians involved in their care, felt that they received extra attention, or if the teaching atmosphere did not inconvenience them. Despite the stated willingness of patients to help with surgical resident education, 32% answered that they would not want residents doing any of their operation. CONCLUSIONS: Surgical resident education is well received and considered important by patients. Patient orientation to the resident education process is vital to patients' perceptions of care and may render patients more willing to participate in educational activities.

Smad4 mediates activation of mitogen-activated protein kinases by TGF-beta in pancreatic acinar cells.

Transforming growth factor-beta (TGF-beta) inhibits pancreatic acinar cell growth. In many cell types, TGF-beta mediates its growth inhibitory effects by activation of Smad proteins. Recently, it has been reported that Smad proteins may interact with the mitogen-activated protein (MAP) kinase signaling pathways. In this study, we report on the interactions between the TGF-beta and MAP kinase signaling pathways in isolated rat pancreatic acinar cells. TGF-beta activated the MAP kinases extracellular signal-related kinases (ERKs) and p38 in pancreatic acinar cells, but had no effect on c-jun NH2-terminal kinase activity. Activation of MAP kinase by TGF-beta was maximal 4 h after treatment. The ability of TGF-beta to activate ERKs was concentration dependent and dependent on protein synthesis. TGF-beta's stimulation of ERK activation was blocked by PD-98059, an inhibitor of MAP kinase kinase 1, and by adenoviral transfer of dominant negative RasN17. Furthermore, adenoviral-mediated expression of dominant negative Smad4 blocked the ability of TGF-beta to activate acinar cell MAP kinase, demonstrating that this activation is downstream of Smads. The biological relevance of ERK activation by TGF-beta was indicated by demonstrating that inhibition of ERK signaling by PD-98059 blocked the ability of TGF-beta to activate the transcription factor activator protein-1. These studies provide new insight into the signaling mechanisms by which TGF-beta mediates biological actions in pancreatic acinar cells.

Adenovirus-mediated gene transfer of dominant-negative Smad4 blocks TGF-beta signaling in pancreatic acinar cells.

Transforming growth factor-beta (TGF-beta) is a potent inhibitor of pancreatic acinar cell growth. Smad4 is a central mediator in the TGF-beta signaling pathway. To study the effect of Smad4 on pancreatic growth, cell cycle protein expression, and the expression of a TGF-beta-responsive promoter in vitro, we constructed an adenovirus containing dominant-negative COOH terminal truncated Smad4 (AddnSmad4) downstream of the rat elastase promoter. Acinar cells expressed dominant-negative Smad4 within 8 h after infection, and expression persisted for 72 h. Mouse pancreatic acini were infected with either AddnSmad4 or control adenovirus expressing green fluorescent protein, and TGF-beta was added 8 h after infection. Acinar cells were then incubated for 1, 2, or 3 days, and [(3)H]thymidine incorporation was determined. AddnSmad4 significantly reduced TGF-beta inhibition of [(3)H]thymidine incorporation, with maximal effects on day 3. AddnSmad4 also completely blocked TGF-beta-mediated growth inhibition in the presence of basic fibroblast growth factor. We next examined the effects of AddnSmad4 on TGF-beta-induced expression of the cell cycle regulatory proteins p21(Cip1) and p27(Kip1). TGF-beta induced upregulation of p21(Cip1), which was completely blocked by AddnSmad4. AddnSmad4 also inhibited TGF-beta-induced expression of the TGF-beta-responsive luciferase reporter 3TP-Lux. These results show that Smad4 is essential in TGF-beta-mediated signaling in pancreatic acinar cells.

The "serendipitous" surgical cure of the Zollinger-Ellison syndrome in a patient with multiple endocrine neoplasia type 1 despite an unsuspected diagnosis of either disease.

Zollinger-Ellison syndrome (ZES) is a relatively uncommon disease that usually presents with peptic ulcer disease or refractory diarrhea. It occurs as a component of multiple endocrine neoplasia type 1 (MEN-1) syndrome in more than 25% of cases. Surgical management of MEN-1 ZES remains controversial. In this case report, we describe the serendipitous cure of ZES in a patient with recurrent peptic ulcer disease who underwent two surgical procedures. The diagnosis of MEN-1 ZES syndrome was neither suspected nor recognized during either operation. This case is presented to highlight the important principles in the diagnosis and current management of patients with MEN-1 ZES.

Disruption of TGFbeta signaling pathways in human pancreatic cancer cells.

OBJECTIVE: To investigate whether transforming growth factor beta (TGFbeta) signaling is disrupted in human pancreatic cancer cells, and to study the role of TGFbeta receptors and Smad genes. SUMMARY BACKGROUND DATA: TGFbeta is a known inhibitor of pancreatic growth. Disruption of the TGFbeta signaling pathway may play a role in pancreatic cancer development. METHODS: The effect of TGFbeta on the BxPC-3, MiaPaCa-2, and PANC-1 pancreatic cancer cell lines was evaluated by [3H]thymidine incorporation and a TGFbeta-responsive reporter assay. Expression of TGFbeta receptors and Smads 2 and 3 was assessed by cross-linking assays and reverse transcriptase-polymerase chain reaction (RT-PCR). The ability to restore TGFbeta responsiveness was evaluated by transfection of TGFbeta signaling components. RESULTS: TGFbeta produced little inhibition of DNA synthesis and did not activate a TGFbeta-responsive reporter in pancreatic cancer cell lines. 125TGFbeta cross-linking and RT-PCR confirmed the presence of TGFbeta receptors and Smad2 and Smad3 transcripts. Transfection of TGFbeta receptors or Smads 2 and 3 did not restore responsiveness. However, transfection of Smad4 into the BxPC-3 pancreatic cancer cell line restored TGFbeta responsiveness. CONCLUSIONS: Pancreatic cancer cells show loss of TGFbeta responsiveness. Smads 2 and 3 and TGFbeta receptors are not defective in the cell lines studied. Transfection of Smad4 into one of the cell lines restored TGFbeta responsiveness, suggesting an important role for Smad4 in pancreatic cancer. It is likely that other, as yet unidentified genes are important in TGFbeta resistance in pancreatic cancer cells.

Giant peptic ulcer: a surgical or medical disease?

BACKGROUND: Medical management of giant peptic ulcers has traditionally been associated with significant morbidity and mortality rates, dictating the need for surgical intervention. METHODS: To determine if recent advances in therapy has reduced the number of patients who require surgical procedures, we reviewed the medical records of all patients with peptic ulcers of 2 cm or more at our institution from January 1991 to August 1996. RESULTS: We identified 75 patients with giant ulcers who were followed for a mean duration of 36 months. Sixty-three patients (84%) were managed without operation with a good outcome, documented by healing on repeat esophagogastroduodenoscopy and/or resolution of symptoms. Medical management included treatment of Helicobacter pylori infection, stopping nonsteroidal anti-inflammatory drugs, and potent acid suppression. Endoscopic intervention to control bleeding was successful in 7 patients (9%), and 2 patients (3%) were treated successfully with angiographic embolization. Only 12 patients (16%) required surgical intervention: 6 as the result of bleeding, 2 as the result of perforation, 1 as the result of obstruction, and 3 with intractable disease. CONCLUSIONS: In this series of patients with giant peptic ulcers, most patients (84%) were managed without surgical treatment. Our data suggest that improvements in medical therapy have obviated the need for eventual surgical intervention in most patients with giant ulcers.

Adenoviral-mediated gene transfer of a constitutively active retinoblastoma gene inhibits human pancreatic tumor cell proliferation.

BACKGROUND: The development of pancreatic cancer involves an accumulation of genetic changes, including oncogene activation and mutations in tumor suppressor genes important in cell cycle regulation. As a step to developing gene therapies to restore cell cycle control, we hypothesized that adenoviral-mediated gene transfer of a constitutively active, nonphosphorylatable form of the retinoblastoma gene (AdRb) would inhibit human pancreatic tumor cell proliferation. METHODS: Transfection efficiency was assessed by beta-gal staining with an adenovirus expressing the beta-galactosidase gene (AdLacZ). The effect of AdRb on DNA synthesis in pancreatic cancer cell lines was determined by tritiated thymidine incorporation. Western blotting with an antihemagglutinin antibody directed to the hemagglutinin-tagged AdRb construct was performed to confirm transfection of pancreatic cancer cells. Apoptosis was evaluated with a TUNEL assay. RESULTS: Efficient transfection of human pancreatic cancer cell lines was achieved with AdLacZ. AdRb inhibited tritiated thymidine uptake in the cancer cell lines BxPC-3, MIA PaCa-2, and PANC-1. Western blotting confirmed transfection of cancer cells with AdRb. AdRb did not inhibit growth by apoptosis. CONCLUSIONS: Adenoviral-mediated gene delivery of constitutively active Rb produces significant growth inhibition in human pancreatic cancer cell lines and is not a result of apoptosis. Further studies examining the role of Rb in pancreatic cancer are warranted.

Blunt force injury of the abdominal aorta.

OBJECTIVE: To review the clinical presentation, diagnosis, and management of injury to the abdominal aorta after blunt force trauma. DESIGN: This study was a retrospective review. RESULTS: A total of 5,676 patients were admitted to the University of Michigan Medical Center with traumatic injury. Seven had injuries to the abdominal aorta after a blunt force mechanism. Five patients had operative repair of the aortic injury, of which four involved orthotopic graft placement and one had an extra-anatomic bypass. Two patients had the aortic injury repaired by endovascular stent placement in the angiography suite. One patient died, and lower extremity amputations were performed in three patients. CONCLUSIONS: Surgical repair of abdominal aortic injury is preferable for the unstable patient or those with threatened extremities. In the stable patient with viable limbs, treatment with radiologic placement of endovascular stents may provide a nonoperative option for management.

Acetylcholine-induced calcium signaling associated with muscarinic receptor activation in cultured myenteric neurons.

BACKGROUND: Within the enteric nervous system, acetylcholine (ACh) is an important neurotransmitter. Experimental evidence has suggested that in myenteric neurons, calcium plays a key role in the coupling of cholinergic receptors to secretory responses. STUDY DESIGN: We investigated the effects of ACh on intracellular calcium concentration ([Ca2+]i) in individual myenteric neurons using fura-2 microspectrofluorometry. RESULTS: Resting [Ca2+]i in myenteric neurons was 62.5 +/- 3 nM. Acetylcholine produced dose-dependent increases in [Ca2+]i in myenteric neurons. As the concentration of ACh was increased from 0.1 to 100 microM, both the peak [Ca2+]i response as well as the percentage of responding neurons progressively increased, with a maximal effect at 100 microM (347 +/- 31 nM, 95 percent of neurons). The effect of ACh was not sensitive to pertussis toxin (100 ng/mL). Calcium ion (Ca2+) responses to ACh were abolished by removal of extracellular Ca2+ as well as exposure to nifedipine (10 microM). Characterization of the specific muscarinic subtype(s) involved in ACh-mediated Ca2+ transients was performed using the specific antagonists pirenzepine (M1), gallamine (M2), and 4-DAMP (M3). Pirenzepine (1 microM) blocked increases in [Ca2+]i induced by ACh; gallamine (1 microM) and 4-DAMP (1 microM) had no significant effect. Intracellular Ca2+ responses to ACh were not affected by incubation with the phorbol ester tetradecanoylphorbol-13-acetate (1 microM). CONCLUSIONS: These findings suggest that ACh induces increases in [Ca2+]i in myenteric neurons by promoting influx of extracellular Ca2+ through L-type voltage-dependent Ca2+ channels by activation of the M1 muscarinic receptor subtype. The Ca2+ response does not appear to involve a pertussis toxin-sensitive G protein.

Undescended superior parathyroid gland: a potential cause of failed cervical exploration for hyperparathyroidism.

BACKGROUND: The undescended inferior parathyroid gland is a well-established although infrequent embryologic abnormality resulting in an ectopically located gland usually associated with thymic tissue and is found most commonly within the carotid sheath at the level of the carotid bifurcation. Embryologically undescended superior glands (either normal or enlarged), clearly above the level of the upper pole of the thyroid gland and found within or in approximation to the lateral pharyngeal wall, have not been previously described. METHODS: The locations of all parathyroid glands at the time of cervical exploration were carefully examined as to embryologic origin in a combined experience of more than 3000 patients with primary or secondary hyperparathyroidism. RESULTS: Five patients had enlarged abnormal glands located within or in close approximation to the pharyngeal wall. All were above the upper pole of the thyroid gland. Two were identified at reoperation on the basis of localization studies. One gland was found after resection of a massive concomitant cervical goiter. The other two were found after an extensive search for a superior gland. CONCLUSIONS: Undescended superior glands are extremely rare (0.08%). They are located within or in approximation to the pharynx above the level of the thyroid gland with an unusual blood supply, which supports an embryologic rather than acquired cause for their ectopic location.

Ca2+ signaling through secretagogue and growth factor receptors on pancreatic AR42J cells.

Intracellular signaling by an increase in [Ca2+]i was observed in pancreatic AR42J cells in response to agonists whose receptors are G-protein coupled including cholecystokinin (CCK), bombesin, carbachol, substance P, pituitary adenylate cyclase activating peptide (PACAP), bradykinin, ATP, calcitonin gene related peptide (CGRP), and in response to growth factors EGF and FGF whose receptors are tyrosine kinases. The response to growth factors was smaller both in magnitude and in the percentage of cells responding but was independent of extracellular Ca2+. CCK and carbachol induced sizeable increases in inositol phosphates while growth factors did not. The responses to both carbachol and EGF, however, were blocked by the phospholipase C inhibitor U73122. The tyrosine kinase inhibitor, genestein, blocked the response to EGF but not that to CCK. These data are consistent with two types of signaling mechanisms in AR42J cells. Secretagogues act on receptors which couple through G proteins to induce a large amount of inositol phosphate production and subsequent intracellular Ca2+ mobilization. Growth factors act on receptors which signal through tyrosine kinase activity and in this cell type produced limited amounts of inositol phosphate and a smaller increase in intracellular Ca2+.

Bombesin-mediated calcium fluxes in myenteric plexus neurons.

Dual excitation microfluorimetry (Fura-2) was used to measure changes in intracellular calcium ([Ca2+]i) in individual cultured guinea pig myenteric neurons. Bombesin (5-500 nM) induced concentration-dependent increases in [Ca2+]i responses, with a maximal effect at 500 nM (56% of neurons responding, mean peak Ca2+ response 244 +/- 25 nM vs. basal 65 +/- 7 nM). Removal of Ca2+ from the median did not affect the initial [Ca2+]i peak but eliminated the subsequent plateau phase. The [Ca2+]i responses to bombesin was abolished by preincubation with thapsigargin (1 microM), a Ca(2+)-ATPase inhibitor (91 +/- 7% inhibition). [Ca2+]i responses to bombesin were inhibited by U73122 (1 microM), an inhibitor of phospholipase C (84 +/- 6% inhibition).

Nerve growth factor promotes neurite outgrowth in guinea pig myenteric plexus ganglia.

Nerve growth factor (NGF) has important developmental actions in both central and peripheral nervous systems. Primary cultures of neonatal guinea pig myenteric plexus ganglia were used to examine the ability of NGF to stimulate morphological development in enteric neurons. NGF, in the presence of a serum-free medium, produced dose-dependent increases in neurite density, significant at 1 ng/ml and maximal at 100 ng/ml (4.5-fold increase vs. control). Maximum neurite length was also significantly increased at 1 ng/ml, with maximal effects at 100 ng/ml. Coincubation of NGF (50 ng/ml) with monoclonal NGF antibodies abolished increases in both neurite density (128 +/- 19 processes/mm for control, 369 +/- 19 for NGF, 183 +/- 28 for NGF+monoclonal antibodies) and neurite length. Exposure of enteric neurons to low concentrations of NGF (1 ng/ml) was also associated with increased mRNA levels for cytoskeletal genes. alpha-Tubulin mRNA levels were increased 3.9 +/- 0.7 times basal at 48 h. mRNA levels for microtubule-associated protein 2 were increased threefold at 48 h of NGF incubation. NGF demonstrates activities in cultured enteric ganglia that stimulate morphological development.

Dual pathways regulate neurite outgrowth in enteric ganglia.

Primary cultures of guinea pig myenteric plexus ganglia were used to examine the ability of agents that activate adenylate cyclase or mimic intracellular adenosine 3',5'-cyclic monophosphate (cAMP) to stimulate morphological growth. Dose-dependent increases in neurite length and density were produced in enteric neuronal cultures by forskolin (212% of control), cholera toxin (356% of control), or the permeant cAMP analogues 8-bromoadenosine 3',5'-cyclic monophosphate and dibutyryl cAMP. (R)-p-adenosine 3',5'-cyclic monophosphorothioate, an inhibitor of cAMP-dependent kinases, blocked the growth-promoting effects of cAMP analogues but not of nerve growth factor (NGF). Activation of cAMP-dependent signaling pathways also increased production of mRNA for alpha-tubulin and microtubule-associated protein 2. Dual pathways, regulated by NGF and cAMP-dependent protein kinases, influence growth signaling in enteric ganglia.

Prostaglandin E2 stimulation of acetylcholine release from guinea pig myenteric plexus neurons.

Prostaglandins are widely distributed within the gastrointestinal tract and have important effects on gastrointestinal motility. Although actions upon gastrointestinal smooth muscle have been demonstrated for prostaglandins (PG), neural mechanisms may also be important. The effects of PGE2 on acetylcholine (ACh) release were studied using guinea pig myenteric plexus neurons in primary culture. PGE stimulated the release of ACh in a dose-dependent manner, with a median effective dose (ED50) of 0.8 x 10(-6) M. Involvement of L-type calcium channels was implied by the sensitivity of PGE2-stimulated ACh release to omega conotoxin or diltiazem. In addition, ACh release stimulated by PGE2 could be inhibited by co-incubation with dideoxyadenosine or Rp-cAMPS, agents that act upon cyclic adenosine monophosphate (cAMP)-dependent signaling pathways. PGE2 has direct effects upon myenteric neurons to stimulate cholinergic transmission.