Preexposure to a nonaggressive opponent prevents low-intensity, social-conflict analgesia in mice

In a first experiment, exposure of DBA/2 mice to a small number of attack bites by a C57BL/6 mouse resulted in low-intensity analgesia as assessed by the tail-flick test. The analgesia dissipated within 10 min and was insensitive to naloxone (10 mg/kg, sc) but was antagonized by the irreversible opioid antagonist beta-chlornaltrexamine (5 mg/kg, sc). In a second experiment, preexposure to a nonaggressive C57BL/6 opponent prevented low-intensity analgesia induced by a small number of attack bites 24 hr later. The preexposure effect was abolished by naloxone (10 mg/kg, sc) given before the nonaggressive confrontation. This suggests that the release of endogenous opioids during preexposure interferes with the subsequent activation of endogenous opioid-mediated pain control mechanisms.     

Internalization of sst2, sst3, and sst5 receptors: effects of somatostatin agonists and antagonists.

The uptake of radiolabeled somatostatin analogs by tumor cells through receptor-mediated internalization is a critical process for the in vivo targeting of tumoral somatostatin receptors. In the present study, the somatostatin receptor internalization induced by a variety of somatostatin analogs was measured with new immunocytochemical methods that allow characterization of trafficking of the somatostatin receptor subtype 2 (sst2), somatostatin receptor subtype 3 (sst3), and somatostatin receptor subtype 5 (sst5) in vitro at the protein level. METHODS: Human embryonic kidney 293 (HEK293) cells expressing the sst2, sst3, or the sst5 were used in a morphologic immunocytochemical internalization assay using specific sst2, sst3 and sst5 antibodies to qualitatively and quantitatively determine the capability of somatostatin agonists or antagonists to induce somatostatin receptor internalization. In addition, the internalization properties of a selection of these agonists have been compared and quantified in sst2-expressing CHO-K1 cells using an ELISA. RESULTS: Agonists with a high sst2-binding affinity were able to induce sst2 internalization in the HEK293 and CHO-K1 cell lines. New sst2 agonists, such as Y-DOTA-TATE, Y-DOTA-NOC, Lu-DOTA-BOC-ATE (where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; TATE is [Tyr3, Thr8]-octreotide; NOC is [1-NaI3]-octreotide; and BOC-ATE is [BzThi3, Thr8]-octreotide), iodinated sugar-containing octreotide analogs, or BIM-23244 were considerably more potent in internalizing sst2 than was DTPA-octreotide (where DTPA is diethylenetriaminepentaacetic acid). Similarly, compounds with high sst3 affinity such as KE108 were able to induce sst3 internalization. In sst2- or sst3-expressing cell lines, agonist-induced receptor internalization was efficiently abolished by sst2- or sst3-selective antagonists, respectively. Antagonists alone had no effect on sst2 or sst3 internalization. We also showed that somatostatin-28 and somatostatin-14 can induce sst5 internalization. Unexpectedly, however, potent sst5 agonists such as KE108, BIM-23244, and L-817,818 were not able to induce sst5 internalization under the same conditions. CONCLUSION: Using sensitive and reproducible immunocytochemical methods, the ability of various somatostatin analogs to induce sst2, sst3, and sst5 internalization has been qualitatively and quantitatively determined. Whereas all agonists triggered sst2 and sst3 internalization, sst5 internalization was induced by natural somatostatin peptides but not by synthetic high-affinity sst5 agonists. Such assays will be of considerable help for the future characterization of ligands foreseen for nuclear medicine applications.     

Microbial exposure of rural school children, as assessed by levels of N-acetyl-muramic acid in mattress dust, and its association with respiratory health

BACKGROUND: Endotoxin exposure has been shown to be associated with a decreased prevalence of atopic sensitization and symptoms. Yet endotoxin represents only a part of the indoor microbial exposure. Muramic acid, a constituent of peptidoglycan, is present in gram-negative and gram-positive bacteria in the environment and may therefore serve as an additional marker of microbial exposure. OBJECTIVE: To study the factors determining the level of indoor exposure to muramic acid/peptidoglycan, as well as its potential association with respiratory health. METHODS: In 553 farm and nonfarm school children from Austria, Switzerland, and Germany, mattress dust muramic acid concentrations were determined, and health was assessed by using IgE measurements and questionnaire information. RESULTS: The muramic acid concentration was found to be significantly higher in dust from farm children's mattresses than in dust from nonfarm children's mattresses (157 vs 131 ng/mg). Children with higher mattress dust muramic acid concentrations had a significantly lower prevalence of wheezing (odds ratio of highest vs lowest tertile of muramic acid concentration, 0.3; 95% CI, 0.1-0.9), regardless of farming status and endotoxin exposure. The association for asthma was similar, and no association was found with atopic sensitization. CONCLUSION: Next to endotoxin, muramic acid provides us with an independent marker of microbial exposure. Unlike endotoxin, muramic acid was inversely associated with wheezing rather than with atopic sensitization.     

Selective kainic acid lesions in cultured explants of rat hippocampus

Summary The influence of the excitotoxin kainic acid (KA) on cultivated explants of rat hippocampus was investigated. Addition of 3 M KA to the culture medium over 24–48 h induced a destruction of the pyramidal cells in the CA3 region, whereas the CA1 pyramidal cells and the granule cells were left undamaged. Higher concentrations (10–100 M) of KA destroyed also the latter cell groups. The selectivity of the KA lesion at 3 M was further indicated by the fact that the acetylcholinesterase-positive neurons in the hippocampus were not destroyed through KA administration and that the stereoisomer dihydrokainic acid was ineffective in inducing lesions. Application of tetrodotoxin did not protect the CA3 pyramidal cells from KA lesion, whereas -glutamylaminomethylsulphonic acid (GAMS) only offered a very small, statistically not significant, protection. Baclofen protected the cultures slightly from KA lesions but not when added together with GAMS. Possible mechanisms responsible for the KA lesions in these cultures are discussed.Supported in part by a grant from the Swiss National Foundation for Scientific Research (No. 3.528.-0.83)     

Autoradiography of 14C-choline uptake in endplates and skeletal muscle of mice

Summary The uptake of ¹⁴C-choline into the axonal part of the motor endplate and muscle of mouse diaphragms was investigated by autoradiography. With i. v. doses of 0.1 g/g choline chloride, the uptake into the nerve endings is fast (<2 min) and into muscle slower (>2 min). With higher doses (1.0 g/g) the uptake into muscle tissue is accelerated.The radioactivity in the endplates decreases with a halflife time of 20 min and remains constant in the muscle fibres over 60 min. Denervation by cutting the phrenic nerve reduces the uptake into endplates by 40% within 14 h, but probably induces uptake into regenerating Schwann cells during 30 days. Some compounds with choline-like structure (hemicholinium-3, decamethylen-dicholine, triethyl-choline) reduce the high-affinity uptake of choline into the nerve endings with sublethal doses, whereas tetraethylammonium and N-hydroxyethyl-4-(1-naphthylvinyl)-pyridinium, an inhibitor of cholinacetyltransferase, are less active. Half lethal doses of cocaine, imipramine and reserpine have no significant action on uptake of choline into the endplates. Chlorpromazine slightly diminishes the uptake into endplates. Chlorpromazine and imipramine reduce uptake into the muscle fibres.     

Behavioral effects of hashish in mice

The acute and subchronic effects of hashish extract (20 mg ⁹-THC/kg) on the social interactions between two drug-treated residents and an untreated intruder male were investigated. In this analysis 28 different behavioral elements were recorded.A single drug application suppressed all categories of behavior, except submissive behavior and flight, in dominant and subordinate residents. Treated animals were less active than controls and immobility was very frequent. An elevated total activity, due to an increase in non-social activities, was observed in the untreated intruder males of this group. Social investigation as well as submissive behavior and flight were reduced in these animals.On introduction of an untreated male after the fourth drug treatment of the residents, the drugged males showed tolerance to the sedative and most of the other behavioral effects of the drug, and intruder males behaved quite normally.The formation of a dominant-subordinate relation within the group was influenced neither by a single nor by repeated drug treatment.The acute and subchronic effects of hashish extract on social, especially aggressive behavior of males are compared to those described in previous papers and the variation in the results of the different studies is discussed.     

Cellular detection of sst2A receptors in human gastrointestinal tissue

BACKGROUND AND AIMS: Many neuroendocrine gastrointestinal tumours express receptors for the regulatory peptide somatostatin. Among the five existing somatostatin receptor (sst) subtypes, sst2A is the most frequently expressed in these tumours. However, little information is available about the cellular location of sst2A in corresponding non-neoplastic epithelial tissues. METHODS: We searched for sst2A immunoreactive cells in non-neoplastic gastrointestinal tissues, and evaluated their number and immunohistochemical characteristics with neuroendocrine markers. RESULTS: The gastric antrum showed numerous sst2A cells, situated in the epithelium, corresponding to gastrin containing neuroendocrine cells, while the gastric corpus was largely devoid of sst2A cells, including enterochromaffin-like cells. The remaining foregut, namely the duodenum and proximal jejunum, also contained a large number of sst2A cells, all being neuroendocrine cells and many of them characterised as gastrin cells. Sst2A cells were also detected in the midgut, in low numbers in the epithelium of the distal jejunum and ileum, but not in the appendix vermiformis, the caecum, or the hindgut, despite the large number of neuroendocrine cells present in this area. In addition, sst2A cells were found in the whole gastrointestinal tract in the myenteric and submucosal plexus. CONCLUSIONS: While sst2A receptors on antral gastrin cells presumably mediate somatostatin inhibition of gastrin secretion, the effects of somatostatin on motility and ion transport in the lower gastrointestinal tract may be mediated by sst2A receptors in the neural plexus. These data provide a molecular basis for the physiological actions of somatostatin in human gastrointestinal tissue.     

Neurotensin receptors: a new marker for human ductal pancreatic adenocarcinoma

Background/Aims—New imaging possibilities forearly diagnosis of the devastating exocrine pancreatic adenocarcinomaswould be highly welcome. Recently, pancreatic neuroendocrine tumours have been successfully visualised in vivo on the basis of their highdensity of receptors for the regulatory peptide somatostatin. Unfortunately, exocrine pancreatic tumours do not express sufficient amounts of somatostatin receptors. Therefore overexpression of other regulatory peptide receptors in these tumours needs to be found.
Methods—Receptors for the regulatory peptideneurotensin were evaluated in vitro by receptor autoradiography in 24 ductal pancreatic adenocarcinomas, 20 endocrine pancreatic cancers, 18cases of chronic pancreatitis, and 10 normal pancreatic glands.
Results—Some 75% of all ductal pancreaticadenocarcinomas, most of them differentiated, were neurotensin receptorpositive, whereas endocrine pancreatic cancers did not expressneurotensin receptors. No neurotensin receptors were found in chronicpancreatitis or normal pancreatic tissues, including pancreatic acini,ducts, and islets.
Conclusions—The selective and high expression ofneurotensin receptors in ductal pancreatic adenocarcinomas could formthe molecular basis for potential clinical applications, such as in vivo neurotensin receptor scintigraphy for early tumour diagnosis, radiotherapy with radiolabelled neurotensin analogues, and chemotherapy with neurotensin receptor antagonists.

Keywords:neurotensin receptors; ductal pancreatic carcinomas; chronic pancreatitis; endocrine pancreatic tumours; in vivoscintigraphy; regulatory peptides

     

Environmental determinants of atopic eczema phenotypes in relation to asthma and atopic sensitization

BACKGROUND: There is still uncertainty about the determinants of atopic eczema (AE). To explain the heterogeneity of the disease, different phenotypes of AE have been suggested. METHODS: The cross-sectional PARSIFAL study included 14 893 school-age children of farmers or children attending Steiner schools and their respective reference groups. A detailed questionnaire was completed, and house dust was collected for the measurement of endotoxin and glucans. Atopic sensitization was defined by allergen-specific IgE levels in the serum. RESULTS: In multivariate analyses, helping with haying was the only variable related to a farming environment having a consistent inverse association with both current symptoms and a doctor's diagnosis of AE [aOR = 0.65 (95% CI: 0.46-0.93) and 0.73 (0.51-1.05)], respectively. Severe lower respiratory tract infections (LRTI) in the first 2 years of life and usage of antibiotics ever were found to be positively related only to asthma-associated AE, whereas the effect of LRTI on AE without asthma had an opposite effect. Levels of beta(1-->3)-glucans in mattress dust were inversely related to a doctor's diagnosis of asthma-associated AE [aOR = 0.75 (0.57-0.98)], and endotoxin levels to current symptoms of asthma-associated AE [aOR = 0.73 (0.57-0.94)]. CONCLUSIONS: The analyses of the PARSIFAL study revealed two different phenotypes of AE, depending on the association with asthma and wheezing ever. With regard to the hygiene hypothesis, help with haying, exposure to beta(1-->3)-glucans and endotoxin were found to be inversely associated with the AE phenotype associated with asthma and wheezing.