Receptor mRNA In Rat Brain Research Articles

Arcuate NPY Controls Sympathetic Output and BAT Function via a Relay of Tyrosine Hydroxylase Neurons in the PVN

Neuropepetide Y (NPY) is best known for its powerful stimulation of food intake and its effects on reducing energy expenditure. However, the pathways involved and the regulatory mechanisms behind this are not well understood. Here we demonstrate that NPY derived from the arcuate nucleus (Arc) is critical forthe control of sympathetic outflow and brown adipose tissue (BAT) function. Mechanistically,a key change induced by Arc NPY signaling is a marked Y1 receptor-mediated reduction in tyrosine hydroxylase (TH) expression in the hypothalamic paraventricular nucleus (PVN), which is also associated with a reduction in TH expression in the locus coeruleus (LC) and other regions in the brainstem. Consistent with this, Arc NPY signaling decreased sympathetically innervated BAT thermogenesis, involving the downregulation of uncoupling protein 1 (UCP1) expression in BAT. Taken together, these data reveal a powerful Arc-NPY-regulated neuronal circuit that controls BAT thermogenesis and sympathetic output via TH neurons.

Region‐Specific Expression and Hormonal Regulation of the First Exon Variants of Rat Prolactin Receptor mRNA in Rat Brain and Anterior Pituitary Gland

Recent studies have revealed the occurrence of five first exon variants of the rat prolactin receptor mRNA, suggesting that multiple promoters direct prolactin receptor transcription in response to different regulatory factors. In the present study, regional expression of these first exon variants, as well as two prolactin receptor subtypes generated by alternative splicing, was examined in the brains and anterior pituitary glands of female rats. Expression of the long-form was detected in the choroid plexus, hypothalamus, hippocampus, cerebral cortex and anterior pituitary gland, whereas the short form was detected only in the choroid plexus. E1-3 mRNA, a first exon variant, was detected in the choroid plexus, hypothalamus, and anterior pituitary gland, whereas E1-4 was detected only in the choroid plexus. Other variants were not detectable by the polymerase chain reaction protocol employed in this study. Ovariectomy increased the short form in the choroid plexus and the E1-3 expression in the choroid plexus and pituitary gland, but changes in the long-form and E1-4 expression were minimal. Replacement of oestrogens and prolactin suggest that oestrogens down-regulate E1-3 expression in the choroid plexus and pituitary gland, and that the negative effect of oestrogen is mediated by prolactin in the pituitary gland. The present results revealed the region-specific promoter usage in prolactin receptor mRNA transcription, as well as the involvement of oestrogens in the regulation of E1-3 mRNA expression in the brain and pituitary gland.

Spatio-temporal expression of cysteinyl leukotriene receptor-2 mRNA in rat brain after focal cerebral ischemia

Cysteinyl leukotrienes (CysLTs) induce inflammatory responses mediated by activating CysLT 1 and CysLT 2 receptors. We have recently reported that CysLT 1 receptor expression is increased in rat brain after focal cerebral ischemia and the increased expression is spatio-temporally related to acute neuronal injury and late astrocyte proliferation. Here we report spatio-temporal expression of CysLT 2 receptor mRNA in rat brain after focal cerebral ischemia induced by 30 min of middle cerebral artery occlusion. We found that the neuron density was gradually decreased or disappeared in the ischemic core and boundary zone during 14 days after reperfusion, and the astrocyte population in the boundary zone was increased 3–14 days after reperfusion. In the ischemic core, the expression of CysLT 2 receptor mRNA was increased at 6, 12 and 24 h and then recovered at 3, 7 and 14 days after reperfusion. In the boundary zone, the expression was significantly increased 3, 7 and 14 days after reperfusion. The results suggest that CysLT 2 receptor may be related to the acute neuronal injury and late astrocyte proliferation in the ischemic brain.

Expression of the glucocorticoid-induced receptor mRNA in rat brain

The glucocorticoid-induced receptor (GIR) is an orphan G-protein-coupled receptor awaiting pharmacological characterization. GIR was originally identified in murine thymoma cells, and shows a widespread, yet not completely complementary distribution in mouse and human brain. Expression of the mouse GIR gene is modulated by dexamethasone in the brain and periphery, suggesting that GIR function is directly responsive to glucocorticoid signals. The rat GIR was cloned from rat prefrontal cortex by our group and was shown to be up-regulated following chronic amphetamine. The physiological role of GIR in the rat is not known at present. In order to gain a clearer understanding of the potential functions of GIR in the rat, we performed a detailed mapping of GIR mRNA expression in the rat brain. GIR mRNA showed widespread distribution in forebrain limbic and thalamic structures, and a more restricted distribution in hindbrain areas such as the spinal trigeminal nucleus and the median raphe nucleus. Areas with moderate to high levels of GIR include olfactory regions such as the nucleus of olfactory tract, hippocampus, various thalamic nuclei, cortical layers, and some hypothalamic nuclei. In comparison with previous studies, significant regional differences exist in GIR distribution in mouse and rat brain, particularly in the thalamus, striatum and in hippocampus at a cellular level. Overall, the expression of GIR in rat brain more closely approaches that seen previously in human than mouse, suggesting that rat models may be more informative for understanding the role of GIR in glucocorticoid physiology and glucocorticoid-related disease states. GIR mRNA distribution in the rat indicates a potential role of this receptor in the control of feeding and ingestive behavior, regulation of stress and emotional behavior, learning and memory, and, drug reinforcement and reward.

Sex difference and estrous cycle: expression of prolactin receptor mRNA in rat brain

The short and long forms of prolactin receptor (PRL-R) mRNA have been detected in the female rat brain. The present study aimed to investigate: (1) if the PRL-R mRNA is expressed in the male rat brain; (2) if expression levels in the female brain vary during the estrous cycle. All animals were sacrificed between 12:00 and 14:00 h. Radioactive RNase protection assay was used to measure mRNA levels. The results showed that both forms of PRL-R mRNA were expressed to varying degrees in the choroid plexus (ChP), preoptic area (POA), mediobasal hypothalamus (MBH), cerebral cortex (CTX) and pons-medulla PON) in both male and female rats. The average amount of both forms of PRL-R mRNA in the ChP, POA, MBH of cycling females was significantly higher than in the male rat. Among cycling female rats, the expression levels of both forms of PRL-R mRNA in the ChP, POA and MBH during proestrous were significantly greater than during diestrous or estrous. In proestrous females, the ChP expressed the highest levels of mRNA whereas the CTX contained the lowest. The ratios of short:long form mRNA were not significantly changed according to sex, estrous stage or brain regions although a slightly higher amount of the short form was observed. The detection of PRL-R mRNA in the male rat implicates that PRL may be involved in regulation of brain function in the male subject. The higher levels of PRL-R mRNA in female rats on proestrous suggest that PRL-R may be regulated by PRL or steroid hormones that show a surge on this day.

Developmentally and Regionally Regulated Expression of Growth Hormone Secretagogue Receptor mRNA in Rat Brain and Pituitary Gland

Distribution and development of growth hormone secretagogue receptor (GHS-R) mRNA expression in rat brain and pituitary gland were examined using ribonuclease protection assay. In adult male rats, GHS-R mRNA levels were highest in the pituitary gland, whereas those in the hypothalamus and hippocampus were 57 and 30% of those in the pituitary gland, respectively. Less abundant but detectable levels of GHS-R mRNA were found in the midbrain, pons, and medulla oblongata, but expression was barely detectable in the cerebellum and cerebral cortex. The expression of GHS-R mRNA was detected at late gestation (embryonic day 19) in the pituitary gland, hypothalamus, and brainstem. The mRNA levels increased with age in the pituitary gland, and decreased postnatally in the brainstem, while they remained constant in the hypothalamus during development. In contrast, GHS-R mRNA was not detectable in the hippocampus during the fetal period, but was first detected on postnatal day 7. Expression of GHS-R mRNA was also examined in the spontaneous dwarf rat (SDR), a model for isolated GH deficiency, to examine alterations in GHS-R mRNA expression in a GH-deficient state. GHS-R mRNA levels in the pituitary gland of SDRs were higher than those of control rats, suggesting negative regulation of GHS-R mRNA by GH in this region. GHS-R mRNA levels increased in the hypothalamus of female, but not in male SDRs. In contrast, GHS-R mRNA levels were not affected by GH in the brainstem and hippocampus. These results indicate that region-specific, developmentally regulated expression of GHS-R mRNA may reflect divergent physiological roles of GHS/GHS-R in distinct regions of the central nervous system and the pituitary gland.

Up-regulation of sigma(1) receptor mRNA in rat brain by a putative atypical antipsychotic and sigma receptor ligand.

Sigma(1) (sigma(1)) receptor mRNA expression was studied in the prefrontal cortex, striatum, hippocampus and cerebellum of rat brain by northern blot and in situ hybridization. The effects of a chronic treatment with antipsychotic drugs (haloperidol and clozapine), and with E-5842, a sigma(1) receptor ligand and putative atypical antipsychotic on sigma(1) receptor expression were examined. A significant increase in the levels of sigma(1) receptor mRNA in the prefrontal cortex and striatum after E-5842 administration was observed, while no apparent changes were seen with either haloperidol or clozapine. Our results suggest a long-term adaptation of the sigma(1) receptor at the level of mRNA expression in specific areas of the brain as a response to a sustained treatment with E-5842.

P-106 - An increased level of histamine H2 receptor mRNA in rat brain after chronic administration of methamphetamine

P-106 - An increased level of histamine H2 receptor mRNA in rat brain after chronic administration of methamphetamine

Changes in oxytocin receptor mRNA in rat brain during pregnancy and the effects of estrogen and interleukin-6.

Changes in brain oxytocin receptor (OTR) binding sites during the course of pregnancy may influence the sudden onset of maternal behavior in female rats at parturition. In situ hybridization was used to identify changes in OTR messenger ribonucleic acid (mRNA) expression during pregnancy and parturition. Two patterns of mRNA regulation were observed. Relative to diestrus virgin control females, OTR mRNA was elevated in the lateral septum and medial preoptic area at days 13-15 of pregnancy but not on the morning of parturition. In the central nucleus of the amygdala and ventromedial nucleus of the hypothalamus (VMH), OTR mRNA was most abundant on the morning of parturition. Strong signals for OTR mRNA were detected in the bed nucleus of the stria terminalis, hypothalamic paraventricular nucleus, supraoptic nucleus and suprachiasmatic nucleus. However no group differences were detected in these areas. As estrogen and interleukin-6 have been suggested to modulate OTR gene expression and both are elevated at the time of parturition, their effects on OTR mRNA in the brain were examined. Estrogen and interleukin-6, given simultaneously, significantly elevated the concentration of OTR mRNA in the VMH, but not in the amygdala. The increase in the VMH was significantly greater than that produced by estrogen alone, and interleukin-6 alone had no effects. These results demonstrate that transcriptional regulation of OTR gene expression mediates changes in receptor density in the brain in a region specific manner during pregnancy and suggests a potential mechanism for some of these changes.

Aging decreases the abundance of retinoic acid (RAR) and triiodothyronine (TR) nuclear receptor mRNA in rat brain: effect of the administration of retinoids

Aging is accompanied by troubles resulting from changes in hormonal and nutritional status. Therefore, the abundance of mRNA coding for triiodothyronine (TR) and retinoic acid (RA) nuclear receptors was studied in the brain of young, adult and aged (2.5, 6 and 24 months, respectively) rats. In the brain of aged rats, there was a lower abundance of TR and RAR mRNA and a lower activity of tissue transglutaminase (tTG), an enzyme the gene of which is a target for retinoids. Administration of RA in these rats restored TR and RAR mRNA and the activity of tTG in the brain. The importance of these observations to the function of the aged brain is discussed.

Expression of 5-HT 7 receptor mRNA in rat brain during postnatal development

The present study is the first one to demonstrate the expression of 5-HT 7 receptor mRNA by in situ hybridization during postnatal development. No quantitative developmental changes in the 5-HT 7 gene expression was observed in neocortex, pyramidal layers of CA1 and CA2, dentate gyrus, most of thalamic nuclei, mammillary region, superior colliculus and central gray. However, in retrosplenial cortex, subiculum and medial habenula an increase of labeling is observed between postnatal days (PN) PN15 and PN21. Striatum showed a transient expression during the first stages of development to be undetectable in adults. CA3 pyramidal cell layer, intramediodorsal thalamic nucleus and lateral habenula displayed a high mRNA expression at PN5 and PN8 which decreased throughout development but it was still present in adults. A possible non-neurotransmitter throphic function of 5-HT mediated through 5-HT 7 receptors could be suggested.

254 Distribution of corticosteroid hormone receptor mRNA in rat brain

254 Distribution of corticosteroid hormone receptor mRNA in rat brain

Localization of 5-HT 4 receptor mRNA in rat brain by in situ hybridization histochemistry

Oligonucleotide probes that recognize two cloned splice variants (5-HT 4S and 5-HT 4L) of 5-HT 4 receptors were used to study by in situ hybridization the localization in rat brain of mRNA encoding these receptors. A probe common to both variants reveals high levels of transcripts in olfactory tubercle, some components of the basal ganglia (caudate putamen, ventral striatum), medial habenula and hippocampal formation. Similar patterns of distribution are obtained with probes that recognize each splice variant individually, suggesting that no dramatic differences exist in their respective regional distribution. Comparison of mRNA distribution with receptor distribution as visualized with [ 125I]SB 207710 indicates that 5-HT 4 receptors are localized both somatodendritically in e.g. caudate putamen and on axon terminals in e.g. substantia nigra and globus pallidus.

Distribution of a rat galanin receptor mRNA in rat brain.

In situ hybridization histochemistry has been employed to determine the distribution of the mRNA encoding a recently cloned rat galanin receptor (rGalR1). The galanin receptor mRNA has been found to be discretely localized in rat brain. The most intense hybridization signals were found over neurons in the nucleus of the lateral olfactory tract, in the ventral posterior hippocampus, and in the lateral external subdivision of the parabrachial nucleus. A number of other brain regions also contain significant hybridization signals, including the hypothalamus, brain stem and spinal cord. The localization of rGalR1 mRNA indicates that this receptor may play a role in the varied functions ascribed to GAL, among them feeding, cognition and modulation of sensory information.

Localization of novel corticotropin-releasing factor receptor (CRF2) mRNA expression to specific subcortical nuclei in rat brain: comparison with CRF1 receptor mRNA expression

Corticotropin-releasing factor (CRF) is the primary factor involved in controlling the release of ACTH from the anterior pituitary and also acts as a neurotransmitter in a variety of brain systems. The actions of CRF are mediated by G-protein coupled membrane bound receptors and a high affinity CRF receptor, CRF1, has been previously cloned and functionally characterized. We have recently isolated a cDNA encoding a second member of the CRF receptor family, designated CRF2, which displays approximately 70% homology at the nucleotide level to the CRF1 receptor and exhibits a distinctive pharmacological profile. The present study utilized in situ hybridization histochemistry to localize the distribution of CRF2 receptor mRNA in rat brain and pituitary gland and compared this with the distribution of CRF1, receptor expression. While CRF1 receptor expression was very high in neocortical, cerebellar, and sensory relay structures, CRF2 receptor expression was generally confined to subcortical structures. The highest levels of CRF2 receptor mRNA in brain were evident within the lateral septal nucleus, the ventromedial hypothalamic nucleus and the choroid plexus. Moderate levels of CRF2 receptor expression were evident in the olfactory bulb, amygdaloid nuclei, the paraventricular and suraoptic nuclei of the hypothalamus, the inferior colliculus and 5-HT-associated raphe nuclei of the midbrain. CRF2-expressing cells were also evident in the bed nucleus of the stria terminalis, the hippocampal formation and anterior and lateral hypothalmic areas. In addition, CRF2 receptor mRNA was also found in cerebral arterioles throughout the brain. Within the pituitary gland, CRF2 receptor mRNA was detectable only at very low levels in scattered cells while CRF1 receptor mRNA was readily detectable in anterior and intermediate lobes. This heterogeneous distribution of CRF1 and CRF2 receptor mRNA suggests distinctive functional roles for each receptor in CRF-related systems. The CRF1 receptor may be regarded as the primary neuroendocrine pituitary CRF receptor and important in cortical, cerebellar and sensory roles of CRF. The anatomical distribution of CRF2 receptor mRNA indicates a role for this novel receptor in hypothalamic neuroendocrine, autonomic and general behavioral actions of central CRF.

Distribution and developmental changes in vasopressin V 2 receptor mRNA in rat brain

The extrarenal presence of vasopressin V 2 receptors (V 2Rs) has been suggested but never been demonstrated. We investigated the distribution of V 2R mRNA expression in the brain of newborn and adult rats using the reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH). RT-PCR assay revealed V 2R mRNA in the cerebellum of both newborn and adult rats, and in the cerebrum of newborn but not adult rats. Further examination of the newborn rat brain by ISH showed dense localization of that V 2R mRNA in the choroid plexus, and the neurons of the hippocampus and granular layer of the cerebellum. Epithelial cells and vascular endothelial cells were strongly stained in the choroid plexus. Moreover, expression of V 2R mRNA in the hippocampus of the newborn rat decreased with age and could not be detected in rats more than 2 weeks old, while in the cerebellum V 2R mRNA expression was stable and did not change with development. The results of our study have demonstrated the presence and distribution of V 2R in the brain for the first time, and also show that expression of V 2R mRNA in the hippocampus changes dynamically during the process of development. V 2R may play an important role in the development of the central nervous system.

Regional quantification of D1, D2, and D3 dopamine receptor mRNA in rat brain using a ribonuclease protection assay.

We describe ribonuclease protection assays for dopamine D1, D2, and D3 receptors, and regional quantitation of mRNA levels for these receptors in rat brain. Both D1 and D2 mRNA levels were highest in caudate putamen, where they were found in approximately equal levels. Of the brain regions examined, D3 mRNA was most abundant in hippocampus, hypothalamus, and nucleus accumbens. Levels of D3 mRNA were significantly lower than values for D1 and D2 mRNA in all brain regions studied. Variability was observed between animals for expression of both D1 and D2 mRNA in caudate putamen, with a significant correlation between D1 and D2 mRNA levels in neostriatum (r = 0.942, P < 0.001). This suggests a functional interaction between D1 and D2 receptor mRNA levels in this brain region. Our results are generally consistent with regional distributions previously reported using other methods. These results suggest that DA D2 receptors function both as an auto and as a postsynaptic receptor, while D1 receptors are restricted to a postsynaptic function. Our results demonstrate the utility of this method in studying possible relationships between individual animal variation in regional mRNA expression and behavioral response to pharmacological and other experimental treatments.

Cellular localization of thrombin receptor mRNA in rat brain: expression by mesencephalic dopaminergic neurons and codistribution with prothrombin mRNA

Cell culture studies demonstrating that the serine protease thrombin can induce neuronal and glial process retraction, glial proliferation, and changes in gene expression suggest a role for thrombin in CNS development, plasticity, and response to injury. Most cellular responses to thrombin are mediated by proteolytic activation of the cloned thrombin receptor (TR), a member of the seven transmembrane domain, G-protein-coupled receptor superfamily. As a step toward understanding the role of thrombin and its receptor in the CNS, Northern blot, in situ hybridization, and immunohistochemical techniques were used to analyze the cellular localization of TR mRNA in weanling-age rat brain. TR mRNA was broadly distributed across the neuraxis, although expression was very focal and often anatomically limited within specific neural structures. The greatest hybridization was associated with individual neurons in neocortex, cingulate/retrosplenial cortex, and subiculum, subsets of nuclei in hypothalamus, thalamus, pretectum, and ventral mesencephalon, and discrete cell layers in the hippocampus, cerebellum, and olfactory bulb. Patterns of hybridization included neuronal, glial, and ependymal cells, although white matter was uniformly negative, as were most cerebrovascular endothelial cells. Expression of TR mRNA by astroglia and dopaminergic neurons was confirmed by colocalization with immunoreactivity for glial fibrillary acidic protein (GFAP) in hippocampus and tyrosine hydroxylase in the substantia nigra. Comparison between TR and prothrombin (thrombin's precursor) cRNA hybridization demonstrated distinct but overlapping brain distributions of these transcripts, most clearly evident in postnatally developing, laminated structures. These results suggest widespread utilization of, and multiple physiologic, and possibly pathophysiologic, functions for, the thrombin/TR cell signaling system in the CNS.

Distinct Distributions of Mu, Delta and Kappa Opioid Receptor mRNA in Rat Brain

We present a comprehensive comparison of the anatomical distributions of the cloned mu, delta and kappa opioid receptor mRNA in rat brain. Northern blot analysis revealed that mRNA species encoding the three receptors differed in size and were differentially localized in brain regions. In peripheral tissues analyzed, the 3 mRNA species were detected only in the spinal cord. The distributions of mu, delta and kappa receptor mRNA in rat brain were examined by in situ hybridization histochemistry using gene-specific probes. Mu receptor mRNA was predominately localized to thalamic, brainstem and reticular core nuclei and was highest in the habenular and thalamic nuclei. In contrast, kappa receptor mRNA was expressed in hippocampus including dentate gyrus, hypothalamic and some thalamic nuclei and also present in cortex, caudate putamen, olfactory tubercle and nucleus accumbens. Delta receptor mRNA was prominent in cerebral cortex, olfactory tubercle, hippocampus, caudate putamen and nucleus accumbens. These results show that the mRNA distribution for each opioid receptor subtype in brain is unique and correlate well with the known distribution of the corresponding opioid receptor binding sites.

Transient expression of oxytocin receptor mRNA in the central nervous system during development

Our previous study demonstrated a wide localization of oxytocin receptor mRNA in the adult rat brain (Yoshimura et al., 1993), and present study further revealed the developmental profiles of oxytocin receptor mRNA expression in the central nervous system. The development of oxytocin receptor mRNA in the rat brain was studied by in situ hybridization histochemistry using antisense RNA probe. The positive hybridization signal was firstly found in a dorsal part of the medulla corresponding to the primordium of the dorsal motor nucleus of vagus, and other positive regions progressively appeared after this time. The developmental profile of oxytocin receptor mRNA expression seen in various regions was classified in two types, which were transiently abundant and constantly expressing types. The regions belonging to the first type were the caudate putamen, cingulate cortex, hippocampus, the dorsal subiculum and the anterior thalamic nucleus, whereas the regions belonging to the second type were tenia tecta, olfactory tubercle, the anterior olfactory nuclei, amygdaloid nuclei, the dorsal motor nucleus of vagus and the ventromedial nucleus of hypothalamus. These finding concurred well with those of the ontogenical studies demonstrated by receptor binding autoradiography using oxytocin specific ligand (Tribollet et al., 1989). Taking the results into consideration, oxytocin seems to have functions not only as a neurohypophysial hormone but also as a substance which could be involved in neuronal maturation or a synaptogenesis in some part of the brain.