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.

How Leptin Controls the Drive to Eat

A complex set of brain based systems modulate feeding to maintain constant body weight. The adipose derived-hormone, leptin, plays a crucial role in this control by acting on diverse leptin receptor (LepRb)-expressing neurons in the hypothalamus and brainstem to modify behavior and metabolism. In addition to controlling energy expenditure and satiety, leptin controls motivation and the reward value of food by regulating two interconnected systems: hypocretin (HCRT) neurons and the mesolimbic dopamine (MLDA) system. Modest/acute decreases in leptin levels, as associated with mild caloric restriction, increase MLDA activity and overall food-seeking behavior; in contrast, severe starvation or complete leptin deficiency blunt MLDA activity, along with motivation and associated behaviors. Lateral hypothalamic (LHA) LepRb neurons project to dopamine (DA) neurons in the ventral tegmental area, where neurotensin (NT) release augments MLDA function; these LepRb(NT) cells also innervate HCRT neurons to control Hcrt expression and inhibit HCRT neurons. Ablation of LepRb in these cells abrogates the control of HCRT cells by leptin and decreases activity and MLDA function. We propose that this neural pathway regulates the MLDA, activity, and motivation in response to leptin and nutritional status.

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.

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.

The Effect of Autonomic Nerve System on Neurotensin Induced Motility in Isolated, Vascularly Perfused Rat Colon

BACKGROUND/AIMS: Although neurotensin (NT) stimulates colon motility and the passage of intestinal contents, the associated mechanism of action remains unclear. The objective of this study was to investigate the effects of NT on colon motility using isolated rat colon. METHODS: Intraluminal pressure was measured at both the proximal and distal portions of the isolated colon. An isolated rat colon was perfused with Krebs solution via the superior mesenteric artery. After stabilization, NT was administered in concentrations of 14, 28, 138 and 276 pM. After pretreatment with phentolamine, propranolol, hexamethonium, atropine or tetrodotoxin, NT was administered at a concentration of 276 pM, and then the intraluminal pressure was monitored. RESULTS: NT significantly increased colon motility at concentrations of 14, 28, 138, and 276 in the proximal colon (25.1+/-6.5%, 175.4+/-117.0%, 240.8+/-115.1% and 252.3+/-110.6%, respectively) and in the distal colon (35.6+/-11.8%, 97.5+/-35.1%, 132.7+/-36.7% and 212.1+/-75.2%, respectively). The stimulant effect of NT was more potent in the proximal colon, in a concentration-dependent manner (P<0.05). The stimulant effect of NT was significantly inhibited by atropine at both the proximal and distal colon and by tetrodotoxin at the proximal colon, but not by tetrodotoxin at the distal colon and not by propranolol, phentolamine, or hexamethonium at both the proximal and distal colon. CONCLUSIONS: NT increased colon motility at both the proximal and distal portions of the rat colon. The effects were more prominent at the proximal portion. The results of this study suggest that the stimulant action of NT may be mediated by local cholinergic muscarinic receptors.

Effect of neuropeptide Y and neurotensin on diurnal rhythm of blood pressure and target organ damage for essential hypertension / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effect of plasma neuropeptide Y (NPY), neurotensin (NT) and their relationships on the diurnal rhythm of BP and target organ damage for essential hypertension.</p><p><b>METHODS</b>Ambulatory BP monitoring (ABPM) for 24 hours was performed in ninety patients with essential hypertension and thirty healthy subjects. The patients were divided into two groups: 55 dippers and 35 non-dippers according to the ABPM results. Plasma NPY and NT levels in subjects were measured at 8:00, 16:00 and 2:00 o'clock by using radioimmunoassay method. Target organ functions were measured.</p><p><b>RESULTS</b>The plasma NPY level was higher and NT was lower in patients with hypertension those in normal controls (P < 0.001). Compared with dippers, non-dippers had a higher NPY and a lower NT plasma levels, especially appearing at 2:00 o'clock. The patients with left ventricular hypertrophy, stroke or kidney damage had a higher NPY and a lower NT levels compares with those without target organ damage.</p><p><b>CONCLUSION</b>The changes in plasma NPY and NT may contribute to disturbance of the diurnal rhythm of blood pressure in patients with essential hypertension, especially in those with target organ damages, which may serve as a pathophysiologic mechanism for target organ damages in hypertension.</p>

Effect of Acriflavine-Guanosine Compound (AG60) Treatment on the Gastrointestinal Endocrine Cells of Mouse Inoculated with Ehrlich Carcinoma Cells / 대한해부학회지

To study the tumor-suppression effect of a newly developed anti-tumor agent AG60 [ acriflavine (1) : guanosine (1) composition, Taerim Pharm. Co., Seoul, Korea], each Ehrlich carcinoma (107 cells)-inoculated mouse received the subcutaneous injection of 0.2 ml of saline, 5mg/kg of AG60, and 30 mg/kg of AG60, every other day for two weeks. Animals were sacrificed, and stomach, duodenum, appendix vermiformis and rectal tissues were resected and fixed in 10% neutral formalin. Tissue blocks were washed, dehydrated, embedded and cut in 6 microgram-thick sections. For immunocytochemistry, the streptavidine-biotin-peroxidse method was used with a InnoGenex (San Ramon, Calif., USA) staining kit. The tissues were incubated with rabbit antisera against somatostatin (Biogenesis, Poole, England, UK) diluted 1 : 300, secretin (Biogenesis, Poole, England, UK) diluted 1 : 2,400, neurotensin (Biogenesis, Poole, England, UK) diluted 1 : 2,600, or motilin (Biogenesis, Poole, England, UK) diluted 1 : 1,000 for 24 hour at 4dreeges C, followed by incubation in biotinylated antirabbit IgG and horseradish peroxidase-streptavidin conjugate for 1 hour at room temperature. The antigen-antibody reaction sites were visualized by incubating the sections with diaminobezidine tetrahydrochloride (DAB) for 5~15 minutes at room temperature. After mounting in canada balsam, they were examined in a Leica DM RB microscope. The number of the immunoreactive cells in the area of gastrointestinal mucosae (mean number of immunoreactive cells per 0.25mm2) were observed and calculated. The results are as follows : 1. In the fundic gland of normal mouse, somatostatin immunoreactive cells were detected (18.5+/-0.71), but neurotensin, secretin, or motilin immunoreactive cells were not found. In the duodenal mucosa of normal mouse, somatostatin immunoreactive cells were detected (7.0+/-0.10), but neurotensin, secretin or motilin immunoreactive cells were rarely found. 2. Immunoreactivity of somatostatin, secretin, neurotensin or motilin cells was not found in appendix vermiformis and rectum of normal mouse. 3. On immunocytochemical study, somatostatin immunoreactive cells in the fundic glands of normal, experimental control, AG60 (5mg/kg)-treated, AG60 (30 mg/kg)-treated and 5-fluorouracil (60 mg/kg)-treated groups were 18.5+/-0.71, 10.0+/-4.20, 11.5+/-0.71, 13.5+/-2.10, 11.5+/-2.71, respectively. 4. On immunocytochemical study, somatostatin immunoreactive cells in the duodenal mucosae of normal, experimental control, AG60 (5 mg/kg)-treated, AG60 (30 mg/kg)-treated and 5-fluorouracil (60 mg/kg)-treated groups were 7.0+/-2.10, 0.5+/-2.71, 3.0+/-1.41, 0.5+/-0.71, 2.50+/-0.71, respectively. 5. On immunocytochemical study, secretin immunoreactive cells in the duodenal mucosae of normal, experimental control, AG60 (5 mg/kg)-treated, AG60 (30 mg/kg)-treated and 5-fluorouracil (60 mg/kg)-treated groups were rarely found. 6. On immunocytochemical study, neurotensin and motilin immunoreactive cells in the duodenal mucosae of normal groups were detected, but immunoreactivies were not detected in experimental control, AG60 (5 mg/kg)-treated, AG60 (30 mg/kg)-treated or 5-fluorouracil (60 mg/kg)-treated groups.

Application of reaction time ruler set in occupational and environmental health

In the present study, a simple and very cheap apparatus, in comparison with other sophisticated and expensive imported ones, was used. The cost of this apparatus is L.E. 115 and the cost of the imported ones is about $ 9,000. The study was conducted on 100 male furnace workers exposed to infrared radiation with a mean age of 39.6 +/- 12.0 and a mean education level of 4.75 + 2.80 workers in one of the factories; in addition to 100 male workers with a mean age of 40.2 +/- 12.6 with a mean education level of 4.71 +/- 12.72 as control subjects, who were not exposed to infrared radiation in the same factory in Helwan. A subjective symptoms questionnaire, listing the most common discomforts or troubles in behaviors, the feeling and the sensation, was administrated. The questionnaire chosen for the test battery was developed at the Institute of Occupational Health [Helsinki]. The simple reaction time ruler set assessment for 100 male furnace workers exposed and 100 male workers not exposed showed mean and standard deviation of 277 and 86 for the exposed subjects as well as 220 and 67 for the control group, the difference was statistically significant

Expression of neurotensin/neuromedin N precursor in murine mast cells

We have cloned the mouse neurotensin/neuromedin N (NT/N) gene from the murine mast cell line C1.MC/C57.1 for the first time. The murine NT/N cDNA clone consisted of 765 nucleotides and coded for 169 peptide residues with an N-terminal signal peptide, and the C-terminal region contained of one copy of neurotensin (NT) and one copy of neuromedin N (NN). Total of four Lys-Arg dibasic motifs were present; one each at the middle of the open reading frame, at the N-terminal of NN, at the C-terminal of NT, and between NN and NT. Amino acid sequence analysis of the mouse NT/N revealed 90% homology to that of the rat NT/N gene. NT/N is expressed in routine mast cell lines (C1.MC/C57.1 and P815), but not in murine bone marrow-derived mast cells (BMMCs), murine macrophage cell line (RAW 264.7), nor in murine T cell line (EL-4). NT/N mRNA in C1.MC/C57.1 is highly inducible by IgE cross-linking, phorbol myristate acetate, neurotensin, and substance P. Following the treatment of demethylating agent, 5-azacytidine (5-azaC), the NT/N gene was induced in BMMCs in response to IgE cross-linking. 5-azaC-treated BMMCs did not express the NT/N gene without additional stimuli. These findings suggested that the regulation of NT/N gene expression was dependent on the effects of not only gene methylation but also enhancer and/or repressor proteins acting on the NT/N promoter.

Neurotensin enhances gastric motility in antral circular muscle strip of guinea-pig

Many reports suggest that neurotensin (NT) in the gastrointestinal tract may play a possible role as a neurotransmitter, a circulating hormone, or a modulator of motor activity. NT exerts various actions in the intestine; it produces contractile and relaxant responses in intestinal smooth muscle. This study was designed to investigate the effect of NT on motility of antral circular muscle strips in guinea-pig stomach. To assess the role of Ca2+ influx in underlying mechanism, slow waves were simultaneously recorded with spontaneous contractions using conventional intracellular mircoelectrode technique. At the concentration of 10-7 M, where NT showed maximum response, NT enhanced the magnitude (863 +/- 198%, mean +/- SEM, n = 13) and the frequency (154 +/- 10.3%, n = 11) of spontaneous contractions. NT evoked a slight hyperpolarization of membrane potential, tall and steep slow waves with abortive spikes (278 +/- 50%, n = 4). These effects were not affected by atropine (2 micrometer), guanethidine (2 micrometer) and tetrodotoxin (0.2 micrometer). NT-induced contractile responses were abolished in Ca2+-free solution and reduced greatly to near abolition by 10 micrometer of verapamil or 0.2 mM of CdCl2. Verapamil attenuated the effects of NT on frequency and amplitude of the slow waves. Taken together, these results indicate that NT enhances contractility in guinea-pig gastric antral circular muscle and Ca2+ influx through the voltage-operated Ca2+ channel appears to play an important role in the NT-induced contractile mechanism.

Changes of neuropeptides immunoreactivity according to dehydration in paraventricular nuclei / 대한해부학회지

Dehydration induced an increase in plasma osmotic pressure that causes the release of the neurohypophysial hormone (Vasopresin, Oxytocin) which are synthesized in neurons of the paraventricular (PVN) and supra optic (SON) nuclei in the hypothalamus. On the other hand, PVN which plays an important role as an integration site for the neuroendocrine and autonomic nervous system neurons responded to osmotic stimulation. In this experiment, we studied that the change of several neuropeptidies (AVP: arginine vasopressin, CRF: cor-ticotrophin releasing factor, GAL: galanin, NT: neurotensin. NPY: neuropeptide Y) immunoreactivity in the PVN according to the dehydration. The body weight of the rats decreased during dehydration and various changes were detected in hypothalamic neuropeptidies immunoreactivity.Our results show that: 1. Dehydration significantly increased AVP, CRF and GAL immunoreactivity in the PVN. 2. Dehydration slowly decreased NT immunoreactivity in the PVN. 3. NPY immunoreactive cell bodys were appeared during dehydration which did not observed in PVN at normal group.

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.

Hormonas gastrointestinales en la estimulación enteral mínima en neonatos prematuros enfermos / Gastrointestinal hormone and minimal enteral feeding in sick premature infants

Objetivo. Medir la respuesta hormonal con estimulación enteral mínima (EEM) en prematuros enfermos. Metología. Fueron 41 pacientes, con peso al nacimiento <1800 g, distribuidos en: grupo I (temprano) con inicio del estímulo en menos de cinco días de edad (n=26), y grupo II (tardío) entre 10 y 14 días (n=15). Se hicieron mediciones basales de cuatro hormonas gastrointestinales (gastrina, PIG, motilina y neurotensina y se inició la estimulación con fórmula para prematuros diluida, comenzando un un mL cada dos horas e incrementando un mL diario hasta alcanzar aproximadamente 120 mL como volumen total, y se registraron las mediciones de las hormonas. Resultados. No hubo diferencia intergrupos en peso, edad gestacional, trofismo y estancia hospitalaria. Hubo diferencias intragrupos entre las mediciones basal y final en todas las hormonas en ambos grupos. Los resultados por subgrupos de edad gestacional (menores y mayores de 32 semanas) y eutróficos e hipotróficos mostraron diferencial basal-final. En relación con peso al nacer y volumen de leche de la EEM, los resultados fueron variables. No hubo complicaciones con el uso del EEM. Conclusiones. El EEM favorece la secreción hormonal gastrointestinal en prematuros enfermos aun administrado tardíamente. El EEM no incrementó las complicaciones abdominales. El peso, la edad gestacional, y el grado trofismo no se asocian a la magnitud de la secreción hormonal

Distribution of Neuropeptide mRNA-Containing Neurons and Changes of Their Gene Expression in the Rat Periaqueductal Gray in a Neuropathic Pain Model / 대한해부학회지

The distribution of enkephalin, dynorphin, substance P and neurotensin in the periaqueductal gray[PAG] has been well established by immunohistochemical methods. However, there is little information about the regional distribution of these neuropeptide mRNA-containing neurons in the PAG. The present study was undertaken [1] to elucidate the distribution of these neuropeptide mRNA-containing neurons and to determine of the PAG, [2] to know how peptide expression relates to the proposed functional subdivisions of the PAG and [3] to know how neuropeptide mRNA levels in the PAG change following peripheral neuropathy The results obtained are as follows ; 1. Preproenkephalin[pENK] mRNA-containing neurons are found mostly in the ventrolateral portion at all levels of the PAG. 2. Prodynorphin[pDYN] mRNA-containing neurons are concentrated mostly in the ventrolateral portion at the caudal level of the PAG. 3. Preprotachykinin[pTAK] mRNA-containing neurons are localized mainly in the ventrolateral portion at all levels of the PAG. There is small numbers of pTAK mRNA-containing neurons in the dorsolateral and dorsal portion at all levels of the PAG. 4. Proneurotensin[pNT] mRNA-containing neurons are concentrated mostly in the medial part of ventrolateral portion of the caudal and mid PAG. 5. Peripheral neuropathy induces an increase of pNT mRNA levels in the PAG, while pENK, pDYN and pTAK mRNAs levels show no change. The present results indicate that the pENK, pDYN, pTAK or pNT mRNA-containing neurons are found mainly in the ventrolateral PAG, the area where analgesia is most easily produced and that neurotensin in the PAG may play an important role in modulating chronic neuropathic pain.

Comparison of the effect of hypothalamic neuropeptides upon luteinizing hormone secretion by cultured rat anterior pituitary cells

Bovine median eminence contains a factor difference from gonadotropin-releasing hormone (GnRH) than increases basal luteinizing hormone (LH) secretion and potentiates GnRH-stimulated LH release. We compared the effect of hypothalamic neuropeptides on basal and GnRH-stimulated LH secretion using rat pituitary cells under static incubation conditions to determine if any of them mimics the LH-releasing activity no attributable to GnRH present in bovine median eminence extracts. Both, galanin and eurotensin (10(-9)-10(-5)) stimulated basal LH secretion in a dose-response manner. Galaninincreased 3-4 fold and neurotensin doubled the basal LH secretion. The GnRH antagonist Nal-Glu 10(-6) M abolished the effect of 10(-7) M GnRH and 10(-5)M neurotensin, but did not block the LH-releasing activity of galanin. Leucin-enkephalin, beta-endorphin, substance P and neuropeptide Y (NPY) did not alter basal LH secretion. Neuropeptides produced three types of response on GnRH-stimulated LH release. First...

Anti-implantation role for substance P and neurotensin in rat.

Substance P (SP) and neurotensin (NT), two structurally related peptides with contrasting biological actions, have been shown to have some role in peripheral reproductive processes. Intrauterine microinjection of SP or NT on day 4 or 5 of pregnancy in the rat significantly reduced the number of viable fetuses, weight and glycogen content of the uterus. The number of viable fetuses, uterine weight or glycogen content were not modified when SP/NT was microinjected on day 8, 9, 10 or on day 14, 15 and 16. The results indicate that the peptides possibly exert a direct local alteration in uterine vascular permeability causing failure in implantation.

Behavioral effects of neurotensin applied to periventricular structures of rats

Neurotensin (NT), n active neuropeptide, and bicuculline, a GABA-A receptor antagonist, were microinjected into the rat hypothalaamus (MH) or the dorsal periaqueductal gray matter (DPAG). Bicuculline (80 pmol) produced behavioral activation which included jumping and NT (1-20 nmol) caused a dose-dependent behavioral activation accompanied by catalepsy rather than jumping. These results suggest that the behavioral activation produced by NT may be due to an interaction of the neuropeptide with specific receptors while its cataleptic effect may be attributed to the blockade of dopamine receptors

Neuro-hormônios do trato gastrintestinal / Neurohormones of the gastrointestinal tract

Os autores fazem um breve estudo acerca da neuroendocrinologia do tubo digestivo. Verificam que diversos hormônios podem potencializar ou inibir açöes fisiológicas agindo sobre um órgäo-alvo comum, situado no trato gastrintestinal. Constatam também a existência de síndromes poliendócrinas capazes de produzir níveis séricos elevados de praticamente todos os peptídeos citados, ampliando-se o conceito e extensäo do sistema APUD. Concluem que o mecanismo etiopatogênico de diversas doenças gastrintestinais näo admite explicaçöes simplistas, ou o emprego de práticas terapêuticas, clínicas ou cirúrgicas tidas como definitivas, pois as anormalidades encontradas na estrutura fisiológica do tubo digestivo estäo relacionadas a distúrbios hormonais complexos e ainda obscuros em vários pontos pesquisados