Neurotensin Changes Propulsive Activity into a Segmental Motor Pattern in the Rat Colon

BACKGROUND/AIMS: Neurotensin is a gut-brain peptide with both inhibitory and excitatory actions on the colonic musculature; our objective was to understand the implications of this for motor patterns occurring in the intact colon of the rat. METHODS: The effects of neurotensin with concentrations ranging from 0.1-100 nM were studied in the intact rat colon in vitro, by investigating spatio-temporal maps created from video recordings of colonic motility before and after neurotensin. RESULTS: Low concentration of neurotensin (0.1-1 nM) inhibited propagating long distance contractions and rhythmic propagating motor complexes; in its place a slow propagating rhythmic segmental motor pattern developed. The neurotensin receptor 1 antagonist SR-48692 prevented the development of the segmental motor pattern. Higher concentrations of neurotensin (10 nM and 100 nM) were capable of restoring long distance contraction activity and inhibiting the segmental activity. The slow propagating segmental contraction showed a rhythmic contraction—relaxation cycle at the slow wave frequency originating from the interstitial cells of Cajal associated with the myenteric plexus pacemaker. High concentrations given without prior additions of low concentrations did not evoke the segmental motor pattern. These actions occurred when neurotensin was given in the bath solution or intraluminally. The segmental motor pattern evoked by neurotensin was inhibited by the neural conduction blocker lidocaine. CONCLUSIONS: Neurotensin (0.1-1 nM) inhibits the dominant propulsive motor patterns of the colon and a distinct motor pattern of rhythmic slow propagating segmental contractions develops. This motor pattern has the hallmarks of haustral boundary contractions.

Function and mechanism of neurotensin (NTS) and its receptor 1 (NTSR1) in occurrence and development of tumors / 中国中药杂志

As a neuropeptide, neurotensin (NTS) is widely expressed in central and peripheral nervous system, which is mainly mediated byneurotensin receptor1 (NTSR1) to activate the related downstream signaling pathways. After summarized the function and mechanism of NTS/NTSR1 in various malignant tumors, we found that NTS/NTSR1 played essential roles during tumor initiation and development. NTS/NTSR1 regulates tumor initiation, proliferation, apoptosis, metastasis and differentiation mainly through three pathways, including IP3/Ca2+ /PKC/MAPKs pathway, MMPs/EGFR/MAPKs (PI3K/Akt) pathway, or Rho-GTPsaes and non-receptor tyrosine kinase pathway. Besides, NTS/NTSR1 is also regulated by some upstream pathways and some traditional Chinese medicine preparations and traditional Chinese medicine therapies. In this article, we summarized the function of NTS/NTSR1 and its mechanisms, and discussed the prospective in its application to clinical diagnosis and drugs targeting.

Establishment and application of human CHO/NTR1 system / 药学学报

Neurotensin receptor-1 (NTR1), which can stimulate the intracellular cascade signal pathway, belongs to the large superfamily of G-protein coupled receptors. NTR1 is related to the occurrence and development of several kinds of diseases. In order to screen the inhibitors for the cancers associated with NTR1 protein, we established a CHO (Chinese hamster ovary) cell line in which human neurotensin receptor-1 was highly expressed. The method is to construct the recombinant plasmid which was lysed with the hNTR1 gene and transfect it into CHO cells. After selected with G418, the cell line was evaluated by Western blotting analysis and calcium flux assays. Through the calcium flux assays on FlexStation 3, we got the EC50 value of neurotensin peptide which is the natural NTR1 agonist, and the IC 50 value of SR48692 which is the known NTR1 antagonist. The established human CHO/NTR1 cell line can be used to study the profile of NTR1 biological activity and further screen of NTR1 antagonists and agonists.

Binding chemistry and molecular heterogeneity of neurotensin binding protein(s)/receptor in adult chicken tissues.

The study focuses on the importance of Tyr11 amino acid (AA) and subsequent stereochemistry involved in the binding process of neurotensin (NT) with its receptor (NTR)/binding protein(s) as well as the size heterogeneity. Using the binding of 125I-NT with several chicken tissues, it is identified that one of the crucial factors behind all high affinity (Kd ~10 pM) interactions is due to phenolic-OH (Φ-OH) at the para (p) position of Tyr11 within RRPYIL-CO2H (NT8-13) sequence. Replacing the p-OH only in Tyr11 by substituting with p-Cl, p-F and p-NH2 results in significant change of the binding affinity (Kd); p-OH ≈ p-NH2 (~10 pM), p-Cl (~100 pM), p-F (~120 pM). Interestingly, p-NH2 equals to p-OH displaying the highest affinity. Experiments conducted by binding several of the 125I-azido–NT analogs having azido group attached at different positions within the NT molecule have further confirmed the necessity of RRPYIL sequence for high affinity ligand-receptor interaction. The role of Tryp11 in place of Tyr11 in addition to the results above establishes a significant possibility of H–bonding occurring between p-OH of NT and NTR inside the docking space. Photo labeling of the liver tissue by substituted 125I-Y3-azido-NT analogs shows several specifically labeled bands with considerable range of molecular weight (Mr ~90-30 kDa) variations. These results indicate the existence of molecular heterogeneity concerning the sizes of NTR or else any NT binding proteins in the avian tissues. Further, the study has revealed that besides liver, several other chicken tissues also express similar specific high affinity binding (Kd ~20 pM) with varying capacities (Bmax). The order for Bmax is: liver (1.2 pMol/mg) gall bladder (1.03 pMol/mg) > spleen (0.43 pMol/mg) > brain (0.3 pMol/mg) > colon lung (0.15 pMol/mg). In all cases, the binding was reduced by GTPgS (ED50 ~ 0.05 nM), NEM (ED50 ~ 0.50 mM) and NaCl (ED50 ~30 mM), indicating the existence of NTR identical to the mammalian type-1.

An Association Study of Neurotensin Receptor Gene's Polymorphism with Schizophrenia / 신경정신의학

OBJECTIVES: Neurotensin (NT), of which functions are evoked by its interaction with neurotensin receptors (NTR), coexists with mesolimbic dopamine and regulates endogenous dopamine release. Recent studies have shown that NT with NTR exerts neuroleptic-like activity within the central nervous system and may play an important role in the pathogenesis and in the treatment of schizophrenia. We have examined the genetic association between schizophrenia and tetranucleotide repeat polymorphism in the 3'-flanking region of the NTR gene to investigate the possible contribution of the NTR gene to the schizophrenia susceptibility. METHODS: Among 23 alleles identified, the subjects were 120 patients (male 91, female 29) with schizophrenia and 106 normal healthy controls (male 84, female 22). They were unrelated native Korean. PANSS was used to determine positive or negative subgroup in the schizophrenic patients.Using polymerase chain reaction and polyacrylamide gel electrophoresis, tetranucleotide repeat polymorphism (CCTT and CTTT) in the 3'-flanking region of NTR gene was observed. For a comparison of NTR gene's allelic frequencies between patients with schizophrenia and normal healthy controls, chi-square test and Bonferroni's correction was performed. RESULTS: The frequency of A10 allele (base pair size=399) was significantly higher in normal healthy controls than schizophrenia (x2=16.4902, df=1, p<.000). In the comparison between schizophrenic patients with negative symptoms and normal controls, the frequency of A10 allele was significantly higher in normal healthy control subjects than patients with schizophrenia (x2=21.33, df=1, p<0.001). In the case of male, the frequency of A10 allele of schizophrenia was significantly higher than normal controls (x2=13.71, df=1, p<0.001). CONCLUSIONS: NTR gene was negatively associated with schizophrenia. NTR gene's tetranucleotide repeat polymorphism may provide some protective function against schizophrenia.