Neurotensin mRNA Expression Research Articles

Expression of Neurotensin and Its Receptors Along the Intestinal Tract in Type 2 Diabetes Patients and Healthy Controls.

Enteroendocrine N cells secrete neurotensin (NTS). NTS reduces food intake in rodents and may increase insulin release. In humans, postprandial NTS responses increase following Roux-en-Y gastric bypass, associating the hormone with the glucose- and body weight-lowering effects of these procedures. We looked at N cell density and mucosal messenger RNA (mRNA) expression profiles of NTS and NTS receptors in type 2 diabetes (T2D) patients and healthy controls. Using double-balloon enteroscopy, 12 patients with T2D and 12 sex-, age-, and body mass index-matched healthy controls had mucosa biopsies taken from the entire length of the small intestine (at 30-cm intervals) and from 7 anatomically well-defined locations in the large intestine. Biopsies were analyzed using immunohistochemistry and mRNA sequencing. N cell density and NTS mRNA expression gradually increased from the duodenum to the ileum, while negligible NTS-positive cells and NTS mRNA expression were observed in the large intestine. NTS receptor 1 and 2 mRNA expression were not detected, but sortilin, a single-pass transmembrane neuropeptide receptor of which NTS also is a ligand, was uniformly expressed in the intestines. Patients with T2D exhibited lower levels of NTS-positive cells and mRNA expression than healthy controls, but this was not statistically significant after adjusting for multiple testing. This unique intestinal mapping of N cell density and NTS expression shows increasing levels from the small intestine's proximal to distal end (without differences between patients with T2D and healthy controls), while negligible N-cells and NTS mRNA expression were observed in the large intestine. Sortilin was expressed throughout the intestines in both groups; no NTS receptor 1 or 2 mRNA expression were detected.

Improvement in blastocyst quality by neurotensin signaling via its receptors in bovine spermatozoa during in vitro fertilization.

Previously, we reported that neurotensin (NT), which is expressed in the uterus and oviduct, enhanced bovine sperm capacitation and acrosome reactions. As NT mRNA expression in bovine oviducts increases dramatically in the follicular phase, we hypothesized that NT modulates fertilization and subsequent conception in cattle. The objective of this study was to evaluate the effect of NT on embryo development and blastocyst quality. The rate of embryo cleavage was significantly increased by the addition of NT to the fertilization medium. Furthermore, the total number of cells and numbers of cells in the inner cell mass of blastocysts were significantly increased by NT during in vitro fertilization (IVF). These results suggested that NT enhanced the efficiency of early bovine embryo development and blastocyst quality. The expression of NT receptors (NTRs) in sperm, testes, oocytes, and cumulus cells was evaluated to determine whether NT acted via NTRs in sperm alone or in both male and female reproductive cells during IVF. Immunocytochemistry and reverse transcription polymerase chain reaction revealed that NTR1 and NTR2 were expressed in sperm and testes, but not in oocytes and cumulus cells. We propose that NT selectively acts upon sperm via NTR1 and NTR2 during IVF to improve the cleavage rate and quality of blastocysts, which are important determinants of sperm quality for successful conception. This research supports our hypothesis that NT acts as a key modulator of fertilization and conception in cattle. Further studies are necessary to apply our findings to the industrial framework of bovine reproduction.

Expression of Neurotensin and its Receptors in Pituitary Adenomas

The neurotensin (NT) produced in the hypothalamus and in pituitary gonadotrophs and thyrotrophs participates in neuroendocrine regulation. Recently, the involvement of this peptide in normal and neoplastic cell proliferation has been postulated. In the present study, we evaluated the expression of NT and its receptors (NTR1, 2 and 3) in a series of 50 pituitary adenomas [11 growth hormone (GH)-, eight prolactin (PRL)-, four adrenocorticotrophic hormone (ACTH)- and 27 nonfunctioning adenomas]. NT mRNA expression was significantly higher in functioning compared to nonfunctioning adenomas and with normal pituitary. Nonfunctioning pituitary adenomas showed lower expression of NT mRNA than normal pituitary. In the immunohistochemical study of functioning adenomas, NT was colocalised with GH, PRL and ACTH secreting cells. In nonfunctioning adenomas, the NT immunoreactivity intensity was variable among the samples. NTR3 mRNA expression was observed in all examined samples and was higher in the adenomas, both functioning and nonfunctioning, compared to normal pituitary. By contrast, NTR1 and NTR2 mRNA were not detected in either pituitary adenomas or normal tissue. The higher expression of NTR3, as well as the expression of NT by tumoural corticotrophs, lactotrophs and somatotrophs, which are cells types that do not express this peptide in the normal pituitary, suggests that NT autocrine and/or paracrine stimulation mediated by NTR3 may be a mechanism associated with the tumourigenesis of functioning adenomas.

Prostaglandins mediate lipopolysaccharide effects upon cholecystokinin and neurotensin phenotypes in neuroendocrine corticotropin-releasing hormone neurons: in situ hybridization evidence in the rat

Intraperitoneal injection of the endotoxin lipopolysaccharide produces an inflammation accompanied by immune system activation and secretion of cytokines that stimulate the hypothalamo–pituitary–adrenal (HPA) axis to release the anti-inflammatory corticosterone. Upstream in HPA axis are neuroendocrine corticotropin-releasing hormone neurons in the paraventricular nucleus whose multipeptidergic phenotype changes during inflammation: coexisting corticotropin-releasing hormone and cholecystokinin mRNAs are up-regulated whereas neurotensin mRNA expression is induced de novo. These changes may be mediated by prostaglandins released from perivascular and microglial cells in response to circulating cytokines. We examined by quantitative in situ hybridization histochemistry whether blockade of prostaglandin synthesis by indomethacin alters phenotypic expression in paraventricular nucleus neurons after lipopolysaccharide. Because indomethacin also elevated circulating corticosterone, animals were adrenalectomized and corticosterone replaced. Results showed that i.p. indomethacin administration suppressed lipopolysaccharide effects in a phenotype non-specific manner: one injection was sufficient to prevent both the increase in corticotropin-releasing hormone and cholecystokinin mRNAs expression and the induction of neurotensin mRNA expression. Therefore, neuroendocrine corticotropin-releasing hormone neurons with different peptidergic phenotypes appear to respond as a whole in the acute phase response to systemic infection.

The effects of diphenhydramine and SR142948A on periaqueductal gray neurons and on the interactions between the medial preoptic nucleus and the periaqueductal gray

The midbrain periaqueductal gray contains both neurotensin type-1 and type-2 receptors. Behavioral studies have shown that the analgesic effect of neurotensin is mediated through its interaction with the type-2 receptors. These receptors specifically bind the type-1 histamine antagonist, levocabastine. Recently, it has been shown that another histamine-1 antagonist, diphenhydramine, blocks the analgesic effect of neurotensin. In addition, it has been shown that a non-peptide neurotensin antagonist, SR142948A, binds to both types of neurotensin receptors and blocks the analgesic effect of exogenously applied neurotensin. Major afferents to the periaqueductal gray arise from the medial preoptic nucleus of the hypothalamus. This region contains neurotensinergic neurons, and the expression of neurotensin mRNA in this region increases following cold-water swim stress that leads to opioid-independent analgesia. The goal of this study was to determine whether the responses of periaqueductal gray neurons to stimulation of the medial preoptic nucleus are modified by local injection of diphenhydramine and SR142948A. Because the cellular basis of the effects of diphenhydramine on periaqueductal gray neurons had not been reported, we also examined the effects of diphenhydramine on the baseline-firing rate and synaptic transmission using in vivo and in vitro methods. The results of the in vitro studies indicate that diphenhydramine concentrations above 500 nM significantly reduce the baseline firing of the periaqueductal gray neurons without a significant effect on the frequency of postsynaptic potentials. At concentrations below 100 nM, diphenhydramine has little effect on the baseline-firing rate but partially blocks the response to neurotensin. The results of the in vivo studies showed similar effects of diphenhydramine. At high concentrations it inhibited periaqueductal gray neurons, but at low concentrations it had no effect on the baseline-firing rate and it blocked the response to neurotensin and to medial preoptic nucleus stimulation. Unlike diphenhydramine, SR142948A had virtually no effect on the baseline-firing rate but blocked the response to neurotensin and to stimulation of the medial preoptic nucleus. It is concluded that: (1) SR142948A, at a dose that completely blocks the effect of exogenously applied neurotensin on periaqueductal gray neurons, has little effect on their baseline-firing rates. (2) Because of its effect on the baseline-firing rate, only low doses of diphenhydramine can be used as an antagonist of the neurotensin analgesic effect. (3) Responses of periaqueductal gray neurons to medial preoptic nucleus stimulation is, in part, mediated by a neurotensinergic network within the periaqueductal gray.

Ciproxifan, a Histamine H3-Receptor Antagonist/Inverse Agonist, Potentiates Neurochemical and Behavioral Effects of Haloperidol in the Rat

By using double <i>in situ</i> hybridization performed with proenkephalin and H₃-receptor riboprobes on the same sections from rat brain, we show that histamine H₃receptors are expressed within striatopallidal neurons of the indirect movement pathway. The majority (∼70%) of striatal enkephalin neurons express H₃-receptor mRNAs. This important degree of coexpression of proenkephalin and H₃-receptor mRNAs prompted us to explore the effect of H₃-receptor ligands on the regulation of enkephalin mRNA expression in the striatum. Acute administration of ciproxifan, a H₃-receptor antagonist/inverse agonist, did not modify the expression of the neuropeptide by itself but strongly increased the upregulation of its expression induced by haloperidol. This potentiation (1) was suppressed by the administration of (<i>R</i>)-α-methylhistamine, a H₃-receptor agonist, (2) occurred both in the caudate–putamen and nucleus accumbens, and (3) was also observed with a similar pattern on c-fos and neurotensin mRNA expression. Similarly, whereas it was devoid of any motor effect when used alone, ciproxifan strongly potentiated haloperidol-induced locomotor hypoactivity and catalepsy, two behaviors in which striatal neurons are involved. The strong H₃-receptor mRNA expression in enkephalin neurons suggests that the synergistic neurochemical and motor effects of ciproxifan and haloperidol result from direct H₃/D₂-receptor interactions, leading to an enhanced activation of striatopallidal neurons of the indirect movement pathway. The potentiation of the effects of haloperidol by ciproxifan strengthens the potential interest of H₃-receptor antagonists/inverse agonists to improve the symptomatic treatment of schizophrenia.

Ciproxifan, a histamine H3-receptor antagonist/inverse agonist, potentiates neurochemical and behavioral effects of haloperidol in the rat.

By using double in situ hybridization performed with proenkephalin and H3-receptor riboprobes on the same sections from rat brain, we show that histamine H3 receptors are expressed within striatopallidal neurons of the indirect movement pathway. The majority ( approximately 70%) of striatal enkephalin neurons express H3-receptor mRNAs. This important degree of coexpression of proenkephalin and H3-receptor mRNAs prompted us to explore the effect of H3-receptor ligands on the regulation of enkephalin mRNA expression in the striatum. Acute administration of ciproxifan, a H3-receptor antagonist/inverse agonist, did not modify the expression of the neuropeptide by itself but strongly increased the upregulation of its expression induced by haloperidol. This potentiation (1) was suppressed by the administration of (R)-alpha-methylhistamine, a H3-receptor agonist, (2) occurred both in the caudate-putamen and nucleus accumbens, and (3) was also observed with a similar pattern on c-fos and neurotensin mRNA expression. Similarly, whereas it was devoid of any motor effect when used alone, ciproxifan strongly potentiated haloperidol-induced locomotor hypoactivity and catalepsy, two behaviors in which striatal neurons are involved. The strong H3-receptor mRNA expression in enkephalin neurons suggests that the synergistic neurochemical and motor effects of ciproxifan and haloperidol result from direct H3/D2-receptor interactions, leading to an enhanced activation of striatopallidal neurons of the indirect movement pathway. The potentiation of the effects of haloperidol by ciproxifan strengthens the potential interest of H3-receptor antagonists/inverse agonists to improve the symptomatic treatment of schizophrenia.

A 6-Hydroxydopamine lesion of the mesostriatal dopamine system decreases the expression of corticotropin releasing hormone and neurotensin mRNAs in the amygdala and bed nucleus of the stria terminalis

The mesostriatal dopamine (DA) system is known to play a vital role in extrapyramidal motor responses, and animals with a unilateral 6-hydroxydopamine (6-OHDA) lesion of this system have proved useful in studying the behavioral and neurobiological effects of DA depletion. Less is known about the role of this system in modulating emotional responses, although a number of lines of evidence suggest that dopamine influences emotional behavior. During the course of a study involving rats that had a unilateral 6-OHDA lesion, we discovered a hemispheric asymmetry in the levels of corticotropin releasing hormone (CRH) mRNA in the central nucleus of the amygdala (CEA). The present study was performed in order to determine (1) if the lesion resulted in a decrease in CRH mRNA, and/or if there was upregulation on the intact side, (2) if a similar imbalance in CRH mRNA was observed in other brain regions and (3) if levels of other neuropeptide mRNAs were affected by the lesion. Adult male Sprague–Dawley rats were left unoperated or were pretreated with desipramine and then injected unilaterally with 6-OHDA into the medial forebrain bundle to lesion the ascending mesostriatal DA neurons. Animals were killed 15–31 days following surgery and brain sections processed for CRH, neurotensin and enkephalin mRNAs by in situ hybridization. Levels of CRH and neurotensin mRNAs were decreased on the lesioned side in the CEA and oval nucleus of the BST (BSTov) relative to the intact side and to unoperated controls. Levels of enkephalin mRNA in these regions were not affected by the lesion. These effects appeared specific, because the lesion did not alter CRH mRNA expression in the ventral BST, paraventricular nucleus of the hypothalamus or cortex or neurotensin mRNA expression in the CA1 region of the hippocampus. In contrast, and consistent with previous reports, levels of neurotensin and enkephalin mRNAs were upregulated on the lesioned side of the striatum. This study provides evidence that the mesostriatal DA system regulates CRH and neurotensin mRNA in the BSTov and CEA, suggesting that dopamine may be an important modulator of CRH and neurotensin function within these nuclei. Although the precise mechanisms are not clear, and the involvement of noradrenergic systems cannot be precluded, data are consistent with the idea that dopamine, released in response to a stressful experience for example, interacts with CRH and neurotensin in the extended amygdala to affect emotional responsiveness.

Endogenous neurotensin facilitates enterohepatic bile acid circulation by enhancing intestinal uptake in rats.

Initial studies on the digestive hormone neurotensin (NT) showing that intestinal NT mRNA expression and blood levels were altered in rats fed chow containing bile acid (BA) and the BA chelator cholestyramine led us to investigate the role of NT in the enterohepatic circulation of BA. In fasted, anesthetized rats with common bile ducts cannulated for bile collection, intravenous NT infusion (10 pmol. kg(-1). min(-1)) enhanced BA output relative to control over 3 h in animals administered donor bile into the duodenum (30 microl/min). This suggested that the effect of NT was on the return of BA from the intestine to the liver, which is rate determining in the normal process. In rats prepared as described above and administered [(3)H]taurocholate ([(3)H]TC; 5 mM, 1 ml) duodenally, NT infusion (3-10 pmol x kg(-1) x min(-1)) increased the [(3)H]TC recovery rate in bile approximately twofold, whereas sulfated CCK-8 (12-50 pmol x kg(-1) x min(-1)) had no effect. To investigate the roles of endogenous NT and CCK, we administered [(3)H]TC into the rat duodenum or lower jejunum and tested the effect of the NT antagonist SR-48692 (2 nmol x kg(-1) x min(-1)) or CCK-A antagonist lorglumide (100 nmol x kg(-1) x min(-1)). SR-48692 reduced the [(3)H]TC recovery rate by congruent with 50% and congruent with 24% in the duodenum and jejunum, respectively, whereas lorglumide had no effect. These results suggest that NT or a similar peptide is an endogenous regulator of enterohepatic BA cycling, which acts by enhancing BA uptake in the intestine.

Chronic pain increases brainstem proneurotensin/neuromedin-N mRNA expression: a hybridization-histochemical and immunohistochemical study using three different rat models for chronic nociception

The role of neurotensin in the central nervous system is poorly understood. Exogenous neurotensin has potent antinociceptive effects when injected into the midbrain periaqueductal gray (PAG). Although it is present in terminals, fibers and perikarya within the PAG and other midbrain regions known for their antinociceptive circuits, it is not known whether endogenous neurotensin modulates nociception. We examined the midbrain in three different rat models for nociception to learn whether acute or chronic pain altered neuronal levels of the proneurotensin/neuromedin N mRNA (neurotensin mRNA). The models were: adjuvant-induced polyarthritis, adjuvant-induced unilateral paw inflammation, and unilateral peripheral mononeuropathy caused by ligation of the sciatic nerve. Behavioral observations confirmed that the expected symptoms developed as previously described. Within each of the three experimental models, we performed in situ hybridization histochemistry on coronal sections from three midbrain levels that included the rostral one-third of the PAG, the middle one-third of the PAG, and the caudal one-third of the PAG. At the level of the rostral PAG, we found that neither chronic nor acute nociception altered the frequencies or distributions of neurons containing neurotensin mRNA. In contrast, at the levels of the mid- and caudal one third of the PAG, the early effects of the nociceptive lesions differed from the chronic effects. During the acute phase of each model, increases in either the frequency or field area of neurons that were hybridization-positive for neurotensin mRNA were confined to the ventromedial PAG and the dorsal raphe nucleus. As the nociceptive stimuli became chronic, the early increases in neurotensin mRNA-containing neurons at the level of the middle third of the ventral PAG were diminished but remained above control levels, while increases in neurotensin mRNA began to occur in the midbrain tegmentum lateral to the PAG. The most striking increases in neurotensin mRNA expression were observed 16-17 days after the onset of nociceptive stimuli. At the level of the mid-PAG and caudal PAG, increased hybridization signal intensities and neuron frequencies occurred within the nucleus cuneiformis and the lateral tegmental nuclei, including the pedunculopontine and microcellular tegmental nuclei, as well as the deep mesencephalic nuclei. Hybridization-positive neurons in the tegmental nuclei were not observed at early stages of lesion development, but were a consistent feature of caudal midbrains after nociception became chronic.(ABSTRACT TRUNCATED AT 400 WORDS)

Neurotensin Gene Expression and Behavioral Responses Following Administration of Psychostimulants and Antipsychotic Drugs in Dopamine D3 Receptor Deficient Mice

Exposure to psychostimulants and antipsychotics increases neurotensin (NT) gene expression in the striatum and nucleus accumbens. To investigate the contribution of D3 receptors to these effects we used mice with targeted disruption of the D3 receptor gene. Basal NT mRNA expression was similar in D3 receptor mutant mice and wild-type animals. Acute administration of haloperidol increased NT gene expression in the striatum in D3+/+, D3+/− and D3−/− mice. Similarly, acute cocaine and amphetamine induced NT mRNA expression in the nucleus accumbens shell and olfactory tubercle to a comparable extent in D3 mutants and wild-type mice. Daily injection of cocaine for seven days increased NT mRNA in a restricted population of neurons in the dorsomedial caudal striatum of D3+/+ mice, but not in D3−/− and D3+/− animals. No differences were observed between D3 receptor mutant mice and wild-type littermates in the locomotor activity and stereotyped behaviors induced by repeated cocaine administration. These findings demonstrate that dopamine D3 receptors are not necessary for the acute NT mRNA response to drugs of abuse and antipsychotics but appear to play a role in the regulation of NT gene induction in striatal neurons after repeated cocaine. In addition, our results indicate that the acute locomotor response to cocaine and development of psychostimulant-induced behavioral sensitization do not require functional D3 receptors.

Cold water swim stress increases the expression of neurotensin mRNA in the lateral hypothalamus and medial preoptic regions of the rat brain

Stress-induced analgesia is a well-documented phenomenon that occurs in all mammalian species. Forced cold water swim produces a type of stress-induced analgesia that is independent of mu opioid receptors. The neuropeptide neurotensin (NT) has been implicated in mu opioid-independent analgesia (MOIA), but the circuitry of this system is largely unknown. The medial preoptic area (MPO) and lateral hypothalamus (LH) are two regions that are known to modulate pain processing. These two regions also contain neurotensinergic projections to the periaqueductal gray, a region that has been shown to produce MOIA upon injection of NT. The goal of this study was to determine if cold water swim (CWS) stress, which produces MOIA, activates the NT–ergic systems in these two regions. In situ hybridization results indicate that CWS increases the level of NT mRNA within neurons in the MPO and LH, suggesting that these two regions are activated during this process.

Dopamine D-1 regulation of caudate neurotensin mRNA in the presence or absence of the nigrostriatal dopamine pathway

Changes in extrapyramidal dopamine (DA) function significantly alter the activity of striatal neurotensin (NT) systems. Specifically, stimulation of DA D-1 or D-2 receptors increases or decreases striatal NT tissue levels, respectively. In contrast, removal of D-2 receptor basal activity with either an antagonist or lesion of the nigrostriatal DA projection increases striatal NT content. To understand better the significance of these changes in the levels of NT peptide, we determined the effects of treatment with the selective D-1 agonist, SKF 82958, alone or in combination with a lesion of the nigrostriatal DA pathway, on the levels of NT mRNA in various regions of the caudate nucleus. Removal of at least 90% of this DA pathway significantly increased NT mRNA in most, but not all, regions throughout the caudate nucleus. In contrast, four, but not one, administrations of SKF 82958 (2 mg kg −1 dose −1) increased NT mRNA levels in principally middle, but not rostral, caudate regions. Lesioning the nigrostriatal DA pathway enhanced the effects of SKF 82958 so that a lower, single dose (1 mg/kg) of this D-1 agonist also increased NT mRNA levels predominantly in the middle caudate sections. These findings demonstrate that DA D-1 receptors profoundly regulate the striatal expression of NT mRNA in a regionally selective fashion, which appears to be unique from that principally influenced by DA D-2 regulation.

Chronic cocaine increases neurotensin gene expression in the shell of the nucleus accumbens and in discrete regions of the striatum

The effects of chronic cocaine administration on neurotensin (NT) mRNA expression were investigated in the rat brain using in situ hybridization. Adult Wistar rats were injected daily with cocaine (15 mg/kg i.p.) or saline for 10 days. One hour after the last injection, the brains were removed and coronal sections of the nucleus accumbens and striatum processed for in situ hybridization using a 35S-labeled NT mRNA oligonucleotide probe. Repeated administration of cocaine induced a specific increase in the expression of NT mRNA in the shell of the nucleus accumbens whereas no changes were observed in the core compartment. In addition, cocaine enhanced the expression of the NT gene in neurons confined to the posterior dorsomedial striatum, but did not alter this same region in the anterior striatum. A strong increase in NT mRNA expression was also observed in rats treated with cocaine in the ventrolateral region of the striatum, the fundus striati. No modifications were seen in the dorsolateral or ventromedial striatum, the lateral septum, or the olfactory tubercle. These findings demonstrate that cocaine affects NT mRNA expression in discrete populations of neurons confined to the shell of the nucleus accumbens and dorsomedial and ventrolateral striatum of the rat. The shell of the nucleus accumbens is a limbic area considered the locus of the reinforcing and locomotor activating properties of cocaine while the dorsal striatum is implicated in the regulation of motor output, and appears to be involved in the stereotypies induced by cocaine. The specific increases in NT gene expression induced by chronic cocaine suggest that these changes could be physiologically relevant for the behavioral effects of psychostimulant drugs.

Neurotensin transcription is oppositely regulated during development and regeneration.

Our previous work demonstrated that neurotensin mRNA expression was transiently up-regulated during development in the hypoglossal motoneurone. The present study was carried out to examine how neurotensin mRNA expression changes during nerve regeneration. Following either unilateral resection or crushing of the hypoglossal nerve, mRNA expression was detected by non-radioactive in situ hybridization histochemistry using an alkaline phosphatase-labelled oligonucleotide probe. A reduction in neurotensin mRNA was observed on the operated side after the nerve injury. It took around 2 months for NT mRNA levels to return to normal. Similar down-regulation was observed following crushing, but recovery was more rapid than that observed with sectioning, probably due to the extent of nerve damage. This finding indicates that neurotensin transcription is up-regulated during development but, on the contrary, down-regulated during regeneration.

Opposing roles for dopamine D2 and D3 receptors on neurotensin mRNA expression in nucleus accumbens.

Using in situ hybridization histochemistry in rat nucleus accumbens, we show that the dopamine D3 receptor mRNA is expressed in the ventromedial part of the shell subdivision, where its gross distribution matches that of neurotensin mRNA. In addition, hybridization studies at the cellular level show that a large fraction of the neurotensin neurons co-express the D3 receptor mRNA in this restricted area. In contrast, the dopamine D2 receptor mRNA is expressed mainly in the core and marginally in the shell, at the level of the cone. In rats treated by haloperidol and sulpiride, two D2-like receptor antagonists, but not by SCH 23390, a D1-like receptor antagonist, proneurotensin mRNA was increased in the D2 receptor mRNA-rich areas but decreased in the D3 receptor mRNA-rich areas. This suggests that the D2 and D3 receptors control neurotensin mRNA expression negatively and positively, respectively.

Chronic pain increases brainstem proneurotensin/neuromedin-N mRNA expression: a hybridization-histochemical and immunohistochemical study using three different rat models for chronic nociception

The role of neurotensin in the central nervous system is poorly understood. Exogenous neurotensin has potent antinociceptive effects when injected into the midbrain periaqueductal gray (PAG). Although it is present in terminals, fibers and perikarya within the PAG and other midbrain regions known for their antinociceptive circuits, it is not known whether endogenous neurotensin modulates nociception. We examined the midbrain in three different rat models for nociception to learn whether acute or chronic pain altered neuronal levels of the proneurotensin/neuromedin N mRNA (neurotensin mRNA). The models were: adjuvant-induced polyarthritis, adjuvant-induced unilateral paw inflammation, and unilateral peripheral mononeuropathy caused by ligation of the sciatic nerve. Behavioral observations confirmed that the expected symptoms developed as previously described. Within each of the three experimental models, we performed in situ hybridization histochemistry on coronal sections from three midbrain levels that included the rostral one-third of the PAG, the middle one-third of the PAG, and the caudal one-third of the PAG. At the level of the rostral PAG, we found that neither chronic nor acute nociception altered the frequencies or distributions of neurons containing neurotensin mRNA. In contrast, at the levels of the mid- and caudal one third of the PAG, the early effects of the nociceptive lesions differed from the chronic effects. During the acute phase of each model, increases in either the frequency or field area of neurons that were hybridization-positive for neurotensin mRNA were confined to the ventromedial PAG and the dorsal raphe nucleus. As the nociceptive stimuli became chronic, the early increases in neurotensin mRNA-containing neurons at the level of the middle third of the ventral PAG were diminished but remained above control levels, while increases in neurotensin mRNA began to occur in the midbrain tegmentum lateral to the PAG. The most striking increases in neurotensin mRNA expression were observed 16-17 days after the onset of nociceptive stimuli. At the level of the mid-PAG and caudal PAG, increased hybridization signal intensities and neuron frequencies occurred within the nucleus cuneiformis and the lateral tegmental nuclei, including the pedunculopontine and microcellular tegmental nuclei, as well as the deep mesencephalic nuclei. Hybridization-positive neurons in the tegmental nuclei were not observed at early stages of lesion development, but were a consistent feature of caudal midbrains after nociception became chronic.(ABSTRACT TRUNCATED AT 400 WORDS)

Neurotensin mRNA expression in response to haloperidol is decreased in the dorsolateral striatum of aged rats.

Annals of the New York Academy of SciencesVolume 668, Issue 1 p. 339-341 Neurotensin mRNA Expression in Response to Haloperidol Is Decreased in the Dorsolateral Striatum of Aged Ratsa DORCAS J. DOBIE, Corresponding Author DORCAS J. DOBIE Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington 98195Address for correspondence: Dorcas J. Dobie, M. D., Mailstop RP-10, Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195.Search for more papers by this authorKALPANA M. MERCHANT, KALPANA M. MERCHANT Department of Pharmacology, University of Washington, Seattle, Washington 98195Search for more papers by this authorMURRAY A. RASKIND, MURRAY A. RASKIND Department of Pharmacology, University of Washington, Seattle, Washington 98195 G.R.E.C.C., Seattle Veteran's Affairs Hospital, Seattle, Washington 98108Search for more papers by this authorDANIEL M. DORSA, DANIEL M. DORSA Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington 98195 Department of Pharmacology, University of Washington, Seattle, Washington 98195 G.R.E.C.C., Seattle Veteran's Affairs Hospital, Seattle, Washington 98108 Department of Medicine, University of Washington, Seattle, Washington 98195Search for more papers by this author DORCAS J. DOBIE, Corresponding Author DORCAS J. DOBIE Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington 98195Address for correspondence: Dorcas J. Dobie, M. D., Mailstop RP-10, Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195.Search for more papers by this authorKALPANA M. MERCHANT, KALPANA M. MERCHANT Department of Pharmacology, University of Washington, Seattle, Washington 98195Search for more papers by this authorMURRAY A. RASKIND, MURRAY A. RASKIND Department of Pharmacology, University of Washington, Seattle, Washington 98195 G.R.E.C.C., Seattle Veteran's Affairs Hospital, Seattle, Washington 98108Search for more papers by this authorDANIEL M. DORSA, DANIEL M. DORSA Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington 98195 Department of Pharmacology, University of Washington, Seattle, Washington 98195 G.R.E.C.C., Seattle Veteran's Affairs Hospital, Seattle, Washington 98108 Department of Medicine, University of Washington, Seattle, Washington 98195Search for more papers by this author First published: October 1992 https://doi.org/10.1111/j.1749-6632.1992.tb27369.x a This work was supported by NARSAD, Washington State Mental Health Research Institute, National Institutes of Health Grant #K12 AG 00503, and by the Department of Veterans Affairs. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume668, Issue1The Neurobiology of NeurotensinOctober 1992Pages 339-341 RelatedInformation

Expression of neurotensin messenger RNA in a human carcinoid tumor.

Neurotensin (NT), a distal gut peptide, has important regulatory and trophic effects throughout the gut; however the intracellular mechanisms that regulate the gene expression and release of human NT are not known. The purpose of this endeavor was to study a functioning human pancreatic carcinoid cell line (called BON) in vitro that expresses the NT gene, and to study the effect of the cyclic adenosine monophosphate (cAMP) signal-transduction pathway on the expression and release of human NT. RNA was prepared from BON cell line (which has been established in this laboratory); the RNA was analyzed for NT mRNA expression by Northern hybridization with a complementary DNA probe. RNA blot analysis demonstrated that the NT gene is expressed in BON and is transcribed to two mRNAs of 1.0- and 1.5-kb sizes. In the second part of this study, BON cells were treated with either forskolin (FSK), which increases intracellular levels of cAMP, or with serotonin (5-HT), which reduces cAMP in BON cells. Forskolin produced a dose-dependent increase in NT peptide release and, furthermore, FSK (10(-6) mol/L) rapidly increased NT mRNA abundance 1 hour after addition; conversely, 5-HT (10(-5) mol/L) decreased NT mRNA at 1 hour. Neurotensin mRNA levels returned to control values by 3 hours after either FSK or 5-HT, which suggests that the transcript half-life for NT is relatively short. These findings show that the expression and peptide release of human NT is mediated, in part, by the cAMP signal-transduction pathway. Our human carcinoid cell line will provide a useful model to study the in vitro regulation of NT gene expression and peptide release.

Transient expression of neurotensin mRNA in the mitral cells of rat olfactory bulb during development

The transient expression of neurotensin mRNA in the mitral cells of the rat olfactory bulb was demonstrated during the perinatal period using non-radioactive in situ hybridization in which an alkaline phosphatase labelled oligodeoxynucleotide probe was used. The relative cellular content of neurotensin mRNA signal was measured by use of a microdensitometer. Neurotensin mRNA positive cells were observed in the primordium of mitral cells on embryonic day 14 and their mRNA content increased gradually up to the day of birth. During the first postnatal week, the strength of their neurotensin mRNA signal decreased dramatically, and continued to decrease until in the adult olfactory bulb neurotensin mRNA was no longer detectable. This decrease of the neurotensin mRNA content coincided with a parallel decrease of neurotensin immunoreactivity observed in the lateral olfactory tract.