Bombesin-like peptide recruits disinhibitory cortical circuits and enhances fear memories.

Disinhibitory neurons throughout the mammalian cortex are powerful enhancers of circuit excitability and plasticity. The differential expression of neuropeptide receptors in disinhibitory, inhibitory, and excitatory neurons suggests that each circuit motif may be controlled by distinct neuropeptidergic systems. Here, we reveal that a bombesin-like neuropeptide, gastrin-releasing peptide (GRP), recruits disinhibitory cortical microcircuits through selective targeting and activation of vasoactive intestinal peptide (VIP)-expressing cells. Using a genetically encoded GRP sensor, optogenetic anterograde stimulation, and trans-synaptic tracing, we reveal that GRP regulates VIP cells most likely via extrasynaptic diffusion from several local and long-range sources. In vivo photometry and CRISPR-Cas9-mediated knockout of the GRP receptor (GRPR) in auditory cortex indicate that VIP cells are strongly recruited by novel sounds and aversive shocks, and GRP-GRPR signaling enhances auditory fear memories. Our data establish peptidergic recruitment of selective disinhibitory cortical microcircuits as a mechanism to regulate fear memories.

Synthesis, preclinical, and initial clinical evaluation of integrin αVß3 and gastrin-releasing peptide receptor (GRPR) dual-targeting radiotracer [68Ga]Ga-RGD-RM26-03.

Integrin receptor αvß3 and gastrin-releasing peptide receptor (GRPR) expression of tumors could be detected using PET imaging with radiolabeled Arg-Gly-Asp (RGD) and the antagonistic bombesin analog RM26, respectively. The purpose of this study was to investigate the dual receptor-targeting property of the heterodimer RGD-RM26-03 (denoted as LNC1015), demonstrate the tumor diagnostic value of [68Ga]Ga-LNC1015 in preclinical experiments, and evaluate its preliminary clinical feasibility. METHODS: LNC1015 was designed and synthesized by linking cyclic RGD and the RM26 peptide. Preclinical pharmacokinetics were detected in a PC3 xenograft model using microPET and biodistribution studies. The clinical feasibility of [68Ga]Ga-LNC1015 PET/CT was performed in patients with breast cancer, and the results were compared with those of 18F-fluorodeoxyglucose (FDG). RESULTS: [68Ga]Ga-LNC1015 had good stability in saline for at least 2 h, and favorable binding affinity and specificity were demonstrated in vitro and in vivo. The tumor uptake and retention of [68Ga]Ga-LNC1015 during PET imaging were improved compared with its monomeric counterparts [68Ga]Ga-RGD and [68Ga]Ga-RM26 at all the time points examined. In our initial clinical studies, the tumor uptake and tumor-to-background ratio (TBR) of primary and metastatic lesions in [68Ga]Ga-LNC1015 PET/CT were significantly higher than those in [18F]FDG PET/CT, resulting in high lesion detection rate and tumor delineation. CONCLUSION: The dual targeting radiotracer [68Ga]Ga-LNC1015 showed significantly improved tumor uptake and retention, as well as lower liver uptake than [68Ga]Ga-RGD and [68Ga]Ga-RM26 monomer. The first-in-human study showed high TBRs in patients, suggesting favorable pharmacokinetics and high clinical feasibility for PET/CT imaging of cancer.

Radiopharmaceuticals Targeting Gastrin-Releasing Peptide Receptor for Diagnosis and Therapy of Prostate Cancer.

The high incidence and heavy disease burden of prostate cancer (PC) require accurate and comprehensive assessment for appropriate disease management. Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) cannot detect PSMA-negative lesions, despite its key role in PC disease management. The overexpression of gastrin-releasing peptide receptor (GRPR) in PC lesions reportedly performs as a complementary target for the diagnosis and therapy of PC. Radiopharmaceuticals derived from the natural ligands of GRPR have been developed. These radiopharmaceuticals enable the visualization and quantification of GRPR within the body, which can be used for disease assessment and therapeutic guidance. Recently developed radiopharmaceuticals exhibit improved pharmacokinetic parameters without deterioration in affinity. Several heterodimers targeting GRPR have been constructed as alternatives because of their potential to detect tumor lesions with a low diagnostic efficiency of single target detection. Moreover, some GRPR-targeted radiopharmaceuticals have entered clinical trials for the initial staging or biochemical recurrence detection of PC to guide disease stratification and therapy, indicating considerable potential in PC disease management. Herein, we comprehensively summarize the progress of radiopharmaceuticals targeting GRPR. In particular, we discuss the impact of ligands, chelators, and linkers on the distribution of radiopharmaceuticals. Furthermore, we summarize a potential design scheme to facilitate the advancement of radiopharmaceuticals and, thus, prompt clinical translation.

Gastrin-releasing peptide receptor antagonist RC-3095 inhibits Porphyromonas gingivalis lipopolysaccharide-accelerated atherosclerosis by suppressing inflammatory responses in endothelial cells and macrophages.

OBJECTIVE: Porphyromonas gingivalis (P. gingivalis), one of the major periodontopathogens, is associated with the progression and exacerbation of atherosclerosis. In this study, we aimed to investigate whether the gastrin-releasing peptide receptor antagonist, RC-3095, could attenuate P. gingivalis LPS-induced inflammatory responses in endothelial cells and macrophages, as well as atherosclerosis in an ApoE-/- mouse model treated with P. gingivalis LPS. METHODS: The effect of RC-3095 on P. gingivalis LPS-induced endothelial inflammation was examined using HUVECs and rat aortic endothelium. THP-1 cells were polarized into M1 macrophages by exposure to P. gingivalis LPS, with or without RC-3095. The effect of RC-3095 on atherosclerosis progression was assessed in high-fat-fed male ApoE-/- mice through injections of P. gingivalis LPS, RC-3095, or a combination of both. RESULTS: RC-3095 significantly reduced P. gingivalis LPS-induced leukocyte adhesion to endothelial cells and aortic endothelium by suppressing NF-κB-dependent expressions of ICAM-1 and VCAM-1. In addition, RC-3095 inhibited the P. gingivalis LPS-induced polarization of M1 macrophages by blocking the MAPK and NF-κB signaling pathways. Moreover, RC-3095 decreased the area of atherosclerotic lesions in ApoE-/- mice, which was accelerated by P. gingivalis LPS injection, and lowered the expressions of ICAM-1 and VCAM-1 in the aortic tissue of mice with atherosclerosis. CONCLUSIONS: RC-3095 can alleviate P. gingivalis LPS-induced endothelial inflammation, macrophage polarization, and atherosclerosis progression, suggesting its potential as a therapeutic approach for periodontal pathogen-associated atherosclerosis.

The cckOMA syndrome and its relation to the Zollinger-Ellison syndrome: a diagnostic challenge.

OBJECTIVE: Among patients with enteropancreatic neuroendocrine tumor syndromes only one case with a cholecystokinin (CCK) secreting tumor has been reported. She had significant hyperCCKemia leading to a specific syndrome of severe diarrheas, weight loss, repeated duodenal ulcers and a permanently contracted gallbladder with gallstones. There are, however, reasons to believe that further CCKomas exist, for instance among Zollinger-Ellison patients with normal plasma gastrin concentrations. The present review is a call to gastroenterologists for awareness of such CCKoma patients. METHOD: After a short case report, the normal endocrine and oncological biology of CCK is described. Subsequently, the CCKoma symptoms are discussed with particular reference to the partly overlapping symptoms of the Zollinger-Ellison syndrome. In this context, the diagnostic use of truly specific CCK and gastrin assays are emphasized. The discussion also entails the problem of access to accurate CCK measurements. CONCLUSION: Obviously, the clinical awareness about the CCKoma syndrome is limited. Moreover, it is also likely that the knowledge about the necessary specificity demands of diagnostic gastrin and CCK assays have obscured proper diagnosis of the CCKoma syndromes in man.

Omeprazole taken once every other day can effectively prevent aspirin-induced gastrointestinal mucosal damage in rats.

BACKGROUND: Proton-pump inhibitors (PPIs) prevent aspirin-associated gastric and duodenal mucosal damage. However, long-term use of PPIs can lead to various adverse reactions, such as gastric polyps and enterochromaffin-like cell hyperplasia. Current research indicates that the abovementioned adverse reactions are mainly related to hypergastrinemia. We investigated whether low-frequency administration of omeprazole could effectively repair aspirin-induced mucosal damage and reduce the increase in gastrin levels associated with long-term use of PPIs. METHODS: Sprague‒Dawley rats were divided into four treatment groups: daily aspirin, daily aspirin and omeprazole once every day (qd), daily aspirin and omeprazole once every other day (qod), and daily aspirin and omeprazole once every three days (1/d3). After 15 days of feeding, blood samples were collected, and the stomachs of sacrificed rats were subjected to macroscopic, histological, and immunohistochemical studies. Moreover, in clinical practice, patients with peptic ulcers caused by aspirin took a standard dose of omeprazole (20 mg) every other day. Two months later, gastroscopy was performed to examine the healing of the ulcers. RESULTS: Both the omeprazole qd and omeprazole qod administrations effectively prevented aspirin-induced gastric peptic ulcers, with no significant difference between the two groups in the inhibition of parietal cell secretion of gastric acid and cell apoptosis. However, omeprazole 1/d3 failed to completely prevent aspirin-induced gastric mucosal injury. Notably, the gastrin levels, cell proliferation ability and cholecystokinin B receptor expression of the omeprazole qd group were significantly higher than those of the omeprazole qod group. In clinical work, patients with peptic ulcers caused by aspirin were given a standard dose of omeprazole every other day, and their ulcers healed after 2 months, as observed by gastroscopy. CONCLUSIONS: Omeprazole administration once every other day can effectively prevent aspirin-induced peptic ulcers and reduce hypergastrinemia, which may reduce the long-term adverse effects of PPI treatment.

B12 deficiency-related glossitis is highly associated with high gastrin-17 and low pepsinogen I.

BACKGROUND: The causes of vitamin B12 (B12) deficiency are varied and mainly related to gastric disorders. Glossitis is a common oral manifestation of B12 deficiency and is often first seen by dentists. This study aimed to investigate the correlation between B12 deficiency-related glossitis (B12-def glossitis) and gastric serum biomarkers [gastrin-17(G17), pepsinogen I (PGI), pepsinogen II (PGII), and anti-Helicobacter pylori (H. pylori) antibodies], and preliminarily discuss the etiology of B12-def glossitis. METHODS: A cross-sectional study was conducted in patients complaining of glossodynia, burning sensation, or severe recurrent oral ulcers, but patients with a history of gastrectomy were excluded. All subjects underwent a uniform oral examination and hematological tests. RESULTS: Of 243 patients, 133 with B12-def glossitis were in the case group, and 110 with other oral mucosal diseases (non-glossitis) and normal B12 levels were in the control group. In the case group, 84.2% (112/133) showed high G17 and low PGI levels (G17hi PGIlow ). Univariate logistic regression showed that G17hi PGIlow was a high-risk factor for B12-def glossitis (OR: 92.44; 95% CI: 35.91, 238.02). Subgroup analyses in the case group showed that the G17hi PGIlow group presented with lower B12 levels and a lower positive rate of anti-H. pylori antibodies compared to the non-G17hi PGIlow group. CONCLUSION: Gastric serum biomarkers in patients with B12-def glossitis generally showed G17hi PGIlow , suggesting possible atrophy of gastric corpus and fundus mucosa. The G17hi PGIlow and non-G17hi PGIlow groups may represent different etiologies of B12 deficiency.

Calcitonin levels in autoimmune atrophic gastritis-related hypergastrinemia.

PURPOSE: Calcitonin (Ct) is currently the most sensitive biochemical marker of C-cell disease (medullary thyroid cancer [MTC] and C-cell hyperplasia), but its specificity is relatively low. Our aim was to examine whether autoimmune atrophic gastritis (AAG) and chronic hypergastrinemia, with or without chronic autoimmune thyroiditis (AT), are conditions associated with increased Ct levels. METHODS: Three groups of patients were consecutively enrolled in this  multicentric study: group A consisted of patients with histologically-proven AAG (n = 13; 2 males, 11 females); group B fulfilled the criteria for group A but also had AT (n = 92; 15 males, 77 females); and group C included patients with AT and without AAG (n = 37; 6 males, 31 females). RESULTS: Median Ct levels did not differ between the three groups. Ct levels were undetectable in: 8/13 cases (61.5%) in group A, 70/92 (76.1%) in group B, and 27/37 (73.0%) in group C. They were detectable but ≤ 10 ng/L in 4/13 (30.8%), 20/92 (21.7%) and 7/37 (18.9%) cases, respectively; and they were > 10 ng/L in 1/13 (7.7%), 2/92 (2.2%) and 3/37 (8.1%) cases, respectively (P = 0.5). Only three patients had high Ct levels (> 10 ng/L) and high gastrin levels and had an MTC. There was no correlation between Ct and gastrin levels (P = 0.353, r = 0.0785). CONCLUSIONS: High gastrin levels in patients with AAG do not explain any hypercalcitoninemia, regardless of whether patients have AT or not. This makes it mandatory to complete the diagnostic process to rule out MTC in patients with high Ct levels and AAG.

Effects of remimazolam tosilate on gastrointestinal hormones and gastrointestinal motility in patients undergoing gastrointestinal endoscopy with sedation: a randomized control trial.

PURPOSE: To investigate the impacts of remimazolam tosilate on gastrointestinal hormones and motility in patients undergoing gastrointestinal endoscopy with sedation. METHODS: A total of 262 American Society of Anesthesiologists Physical Status I or II patients, aged 18-65 years, scheduled for gastrointestinal endoscopy with sedation, were randomly allocated into two groups (n = 131 each): the remimazolam tosilate group (Group R) and the propofol group (Group P). Patients in Group R received 0.2-0.25 mg/Kg remimazolam tosilate intravenously, while those in Group P received 1.5-2.0 mg/kg propofol intravenously. The gastrointestinal endoscopy was performed when the Modified Observer's Assessment of Alertness/Sedation scores were ≤3. The primary endpoints included the endoscopic intestinal peristalsis rating by the endoscopist; serum motilin and gastrin levels at fasting without gastrointestinal preparation (T0), before gastrointestinal endoscopy (T1), and before leaving the Post Anesthesia Care Unit (T2); and the incidences of abdominal distension during Post Anesthesia Care Unit. RESULTS: Compared with Group P, intestinal peristalsis rating was higher in Group R (P < .001); Group R showed increased motilin and gastrin levels at T2 compared with Group P (P < .01). There was a rise in motilin and gastrin levels at T1 and T2 compared with T0 and at T2 compared with T1 in both groups (P < .01). The incidence of abdominal distension was lower in Group R (P < .05). CONCLUSION: Compared with propofol used during gastrointestinal endoscopy with sedation, remimazolam tosilate mildly inhibits the serum motilin and gastrin levels, potentially facilitating the recovery of gastrointestinal motility.

Estrogens influence female itch sensitivity via the spinal gastrin-releasing peptide receptor neurons.

There are sex differences in somatosensory sensitivity. Circulating estrogens appear to have a pronociceptive effect that explains why females are reported to be more sensitive to pain than males. Although itch symptoms develop during pregnancy in many women, the underlying mechanism of female-specific pruritus is unknown. Here, we demonstrate that estradiol, but not progesterone, enhances histamine-evoked scratching behavior indicative of itch in female rats. Estradiol increased the expression of the spinal itch mediator, gastrin-releasing peptide (GRP), and increased the histamine-evoked activity of itch-processing neurons that express the GRP receptor (GRPR) in the spinal dorsal horn. The enhancement of itch behavior by estradiol was suppressed by intrathecal administration of a GRPR blocker. In vivo electrophysiological analysis showed that estradiol increased the histamine-evoked firing frequency and prolonged the response of spinal GRP-sensitive neurons in female rats. On the other hand, estradiol did not affect the threshold of noxious thermal pain and decreased touch sensitivity, indicating that estradiol separately affects itch, pain, and touch modalities. Thus, estrogens selectively enhance histamine-evoked itch in females via the spinal GRP/GRPR system. This may explain why itch sensation varies with estrogen levels and provides a basis for treating itch in females by targeting GRPR.