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S J Watson

Publications and source records attributed to S J Watson.

At least 127 records · Page 7Linked to original sources
PubMed1995

The cloned mu, delta and kappa receptors and their endogenous ligands: evidence for two opioid peptide recognition cores.

The opioid peptides are derived from three prohormone precursors referred to as proopiomelanocortin (POMC), proenkephalin (ProEnk) and prodynorphin (ProDyn). Following specific cleavage, several biologically active peptides are generated that can bind to the mu, delta and kappa receptors. The present study examines the receptor binding affinities of the POMC, ProEnk and ProDyn peptides to the cloned mu, delta and kappa receptors expressed transiently in transfected COS-1 cells. Consistent with previous findings using brain homogenates, competition studies demonstrate that no opioid peptide family can be exclusively associated with a specific opioid receptor type. Short ProEnk peptides, such as Leu- and Met-enkephalin are selective for delta, but C-terminally extended peptides such as Met-Enk-Arg-Gly-Leu and Met-Enk-Arg-Phe have a high affinity to micro, delta and kappa. Similarly, Peptide E, the BAM peptides, and metorphamide have a high affinity for all three opioid receptor types. While dynorphin A peptides and alpha- and beta-neoendorphin have a preference for kappa, they also bind the cloned delta and mu receptors. Our findings do not easily fit a simple 'message-address' model where the Try-Gly-Gly-Phe core is extended and this gradually alters selectivity. Rather, the pattern appears more discontinuous, and would fit better with the idea of two similar but distinct cores; a Try-Gly-Gly-Phe Met- or Leu core that is necessary and sufficient for mu and delta but not kappa and a Tyr-Gly-Gly-Phe-Met or Leu core with an Arg-X extension that is equally necessary and sufficient for kappa.

Amino Acid Sequence↗
PubMed1995

Dopamine receptor mRNA expression patterns by opioid peptide cells in the nucleus accumbens of the rat: a double in situ hybridization study.

Colocalization of proenkephalin and prodynorphin mRNAs with each other as well as with D1, D2, and D3 dopamine receptor mRNAs was analyzed in the nucleus accumbens of the rat. Distinct combinations were detected in the rostral pole, core, and shell subdivisions of the nucleus accumbens. Proenkephalin and prodynorphin mRNAs were principally localized in separate cells in the core. All detectable prodynorphin cells in the core expressed D1 mRNA but not D2 mRNA. Conversely, approximately 95% of the proenkephalin-positive cells in this region expressed D2 mRNA but not D1 mRNA. This pattern was identical to that observed in the caudate putamen. In the rostral pole and the shell, embedded in a background of this "typical" colocalization pattern, clusters of cells expressing a distinct configuration were found. In these clusters, proenkephalin-positive cells expressed both prodynorphin and D1 mRNAs, but they did not express D2 mRNA. D3 and prodynorphin mRNAs were colocalized in "limbic" striatal areas, including the ventromedial caudate putamen, the rostral pole, and the medial shell. In contrast, D3 mRNA was not detected in any proenkephalin-positive cells. Together with the prodynorphin/D1 data, this suggests that a subset of prodynorphin cells expresses both D1 and D3 mRNAs. It is concluded that 1) clusters of cells that coexpress proenkephalin, prodynorphin, and D1 mRNAs overlap extensively with previously defined cytoarchitectural cell clusters in the nucleus accumbens and 2) a subset of the prodynorphin cells in the ventromedial caudate putamen and the nucleus accumbens contains both D1 and D3 mRNAs.

Animals↗
PubMed1995

A chimeric study of the molecular basis of affinity and selectivity of the kappa and the delta opioid receptors. Potential role of extracellular domains.

Within the large family of G-protein-coupled receptors, a picture is emerging which contrasts the binding of small ligands and the binding of peptides to the seven-helix configuration of the proteins. Because of its unique richness in both peptide and non-peptide ligands, the opioid receptor family offers several advantages for achieving a better understanding of similarities and differences in ligand/receptor interactions across different classes of agonists and antagonists. Since multiple, naturally occurring, ligands interact with the multiple receptors with varying degrees of selectivity, this family is also an excellent model for examining the structural basis of selectivity. Thus, the molecular basis of binding affinity and selectivity of the kappa and the delta opioid receptors was investigated by the construction of four kappa/delta chimeric receptors. The pharmacological profiles of these chimeras as well as those of the wild type kappa and delta receptors were determined by their binding with several different categories of opioid ligands. A linear model was used to deduce the relative contribution of each corresponding pairs of kappa-delta receptor segments to the binding of a given ligand. The results show that the kappa and delta receptors bind the same opioid core differently and achieve their selectivity through different mechanisms. In addition, the interaction of a peptide ligand with a receptor appears to be different from that of a small ligand. Furthermore, these results point to a particularly important role of the second extracellular loop and the top half of transmembrane domain 4 in the binding of prodynorphin products. Together, the results suggest that these peptide receptors can be bound and activated via multiple binding pockets as a function of their own topography and the nature of the interacting ligand.

Amino Acid Sequence↗
PubMed1995

Stress regulation of mineralocorticoid receptor heteronuclear RNA in rat hippocampus.

Localization and regulation of mineralocorticoid receptor (MR) heteronuclear RNA (hnRNA) was assessed in rat hippocampus using an intron-directed in situ hybridization approach. The presence of hnRNA in the cell nucleus reflects recent gene transcriptional events and can be used as an index of neuronal transcriptional activation or inhibition. In the present study, sections incubated with an MR intron probe labeled cells in all regions known to contain MR mRNA. Signal generated by the intron probe was localized specifically to the nuclear compartment, consistent with recognition of hnRNA. Analysis of distribution across hippocampus indicated that MR hnRNA was particularly abundant in dentate gyrus (DG). In contrast, MR mRNA shows similar levels of expression across all hippocampal subfields. Exposure of animals to acute restraint markedly reduced MR hnRNA levels in CA1 and DG 60 min and 120 min following stress exposure, consistent with reduced gene transcription. These data support the hypothesis that stress-induced glucocorticoid secretion can rapidly affect transcription of steroid receptor genes. MR mRNA levels did not decrease over comparable time periods, suggesting either a significant lag-time between transcriptional changes and changes in cytoplasmic mRNA pools or stimulus-driven alterations in post-transcriptional RNA processing.

Animals↗
PubMed1995

Evidence against changes in corticotroph CRF receptors in depressed patients.

Previous studies by a number have investigators have documented a decreased adrenocortotropic hormone (ACTH) and beta-lipotropin/beta-endorphin (beta-End) response to ovine corticotropin-releasing factor (oCRF) in depressed patients. Since depressed patients demonstrate higher plasma cortisol concentrations at the time of oCRF challenge, it is difficult to determine if the decreased ACTH response is due to enhanced negative feedback of cortisol on ACTH release or an alteration in CRF receptors in depressed patients. To evaluate the response to oCRF in an "open feedback loop" system, we administered metyrapone 750 mg at 4 PM and 7:30 PM, followed by administration of oCRF 0.3 microgram/kg at 8 PM in 10 normal controls and 10 depressed patients. Administration of metyrapone at this time in the circadian rhythm clamped plasma cortisol concentrations to less than 2 micrograms/dl but did not result in rebound ACTH or beta-End secretion in control subjects. In control subjects, metyrapone administration produced a 85% blockade of the cortisol response as well as a 3-fold greater beta-End response compared to administration of the same dose of oCRF without metyrapone. The 10 depressed patients and their matched controls demonstrated identical beta-End responses (integrated response for controls = 291 +/- 61, for patients = 352 +/- 86) and cortisol responses (integrated response for controls = 187 +/- 38, for patients = 206 +/- 52) to oCRF following metyrapone pretreatment. These data confirm that corticotroph CRF receptors are normal in depressed patients, and that cortisol feedback plays an essential role in the abnormal ACTH and beta-End response to oCRF in depressed patients.

Adrenocorticotropic Hormone↗
PubMed1995

Non-inflammatory rectovaginal fistula.

The results of surgical repair of straightforward rectovaginal fistula in 26 women (obstetric, 13; infection, nine; trauma, one; unknown but not radiation-induced or related to inflammatory bowel disease, three) were ultimately excellent; 23 patients were cured. However, this result obscures a high early failure rate in five of 12 patients having a transanal advancement flap and in one of eight having perineoproctotomy (lay open and repair). A temporary stoma was used in 11 patients (five of eight with a perineoproctotomy, three of 12 with an advancement flap and in three having another local procedure.

Adult↗
PubMed1995

Opioid-receptor mRNA expression in the rat CNS: anatomical and functional implications.

The cloning of the opioid receptors has profoundly affected our understanding of opioid-receptor expression, regulation and function. This review focuses on the impact that cloning has had on our understanding of opioid-receptor anatomy, and provides broad anatomical maps of the three opioid-receptor mRNAs in relation to their binding sites. In addition, three model anatomical systems, the nigrostriatal and mesolimbic dopamine systems, the hypothalamic neuroendocrine axes, and the ascending and descending pain pathways, have been highlighted to discuss issues of receptor transport, trafficking and pre- versus postsynaptic localization.

Animals↗
PubMed1995

Pattern and time course of immediate early gene expression in rat brain following acute stress.

The pattern and time course of brain activation in response to acute swim and restraint stress were examined in the rat by in situ hybridization using complementary RNA probes specific for transcripts encoding the products of the immediate early genes c-fos, c-jun and zif/268. A widespread pattern of c-fos messenger RNA expression was detected in response to these stressors; surprisingly, the expression patterns were substantially similar following both swim and restraint stress. A dramatic induction of c-fos messenger RNA was observed in numerous neo- and allocortical regions, the lateral septal nucleus, the hypothalamic paraventricular and dorsomedial nuclei, the anterior hypothalamic area, the lateral portion of the retrochiasmatic area, the medial and cortical amygdaloid nuclei, the periaqueductal gray, and the locus coeruleus; however, a prominent induction of c-fos was also seen in numerous additional subcortical and brainstem regions. Although not as widely expressed in response to stress as c-fos, induction of zif/268 messenger RNA was also detected throughout many brain areas; these regions were largely similar to those in which c-fos was induced, although in a number of regions zif/268 was expressed in regions devoid of c-fos messenger RNA. Few brain areas showed increased expression of c-jun following stress; these regions also showed induction of c-fos and/or zif/268. The time courses of expression of all three immediate early genes were similar, with peak levels observed at the 30 or 60 min time point, and a markedly reduced signal evident at 120 min post-stress. However, in a number of cases a delayed and/or prolonged induction was noted that may be indicative of secondary neuronal activation. A number of recent studies have attempted to define neural pathways which convey stress-related information to the hypothalamic-pituitary-adrenal axis. The present results reveal a widespread pattern of neuronal activation in response to acute swim or restraint stress. These findings may aid in the identification of stress-specific neural circuits and are thus likely to have important implications for our understanding of neuronal regulation of the stress response.

Animals↗
PubMed1995

Immunohistochemical localization of the cloned mu opioid receptor in the rat CNS.

Three opioid receptor types have recently been cloned that correspond to the pharmacologically defined mu, delta and kappa 1 receptors. In situ hybridization studies suggest that the opioid receptor mRNAs that encode these receptors have distinct distributions in the central nervous system that correlate well with their known functions. In the present study polyclonal antibodies were generated to the C terminal 63 amino acids of the cloned mu receptor (335-398) to examine the distribution of the mu receptor-like protein with immunohistochemical techniques. mu receptor-like immunoreactivity is widely distributed in the rat central nervous system with immunoreactive fibers and/or perikarya in such regions as the neocortex, the striatal patches and subcallosal streak, nucleus accumbens, lateral and medial septum, endopiriform nucleus, globus pallidus and ventral pallidum, amygdala, hippocampus, presubiculum, thalamic and hypothalamic nuclei, superior and inferior colliculi, central grey, substantia nigra, ventral tegmental area, interpeduncular nucleus, medial terminal nucleus of the accessory optic tract, raphe nuclei, nucleus of the solitary tract, spinal trigeminal nucleus, dorsal motor nucleus of vagus, the spinal cord and dorsal root ganglia. In addition, two major neuronal pathways, the fasciculus retroflexus and the stria terminalis, exhibit densely stained axonal fibers. While this distribution is in excellent agreement with the known mu receptor binding localization, a few regions, such as neocortex and cingulate cortex, basolateral amygdala, medial geniculate nucleus and the medial preoptic area fail to show a good correspondence. Several explanations are provided to interpret these results, and the anatomical and functional implications of these findings are discussed.

Amino Acid Sequence↗
PubMed1995

Contribution of the ventral subiculum to inhibitory regulation of the hypothalamo-pituitary-adrenocortical axis.

Anatomical studies indicate that the ventral subiculum is in a prime position to mediate hippocampal inhibition of the hypothalamo-pituitary-adrenocortical (HPA) axis. The present study evaluated this hypothesis by assessing HPA function following ibotenic acid lesion of the ventral subiculum region. Rats with lesions of the ventral subiculum (vSUB) or ventral hippocampus (vHIPPO) did not show changes in basal corticosterone (CORT) secretion at either circadian peak or nadir time points when compared to sham-lesion rats (SHAM) or unoperated controls. However, rats with vSUB lesions exhibited a prolonged glucocorticoid stress response relative to all other groups. Baseline CRH mRNA levels were significantly increased in the medial parvocellular paraventricular nucleus (PVN) of the vSUB group relative to controls. CRH mRNA differences were particularly pronounced at caudal levels of the nucleus, suggesting topographic organization of vSUB interactions with PVN neurons. Notably, the vHIPPO group, which received large lesions of ventral CA1, CA3 and dentate gyrus without significant subicular damage, showed no change in stress-induced CORT secretion, suggesting that the ventral subiculum proper is principally responsible for ventral hippocampal actions on the HPA stress response. No differences in medial parvocellular PVN AVP mRNA expression were seen in either the vSUB or vHIPPO groups. The results indicate a specific inhibitory action of the ventral subiculum on HPA activation. The increase in CRH biosynthesis and stress-induced CORT secretion in the absence of changes in baseline CORT secretion or AVP mRNA expression suggests that the inhibitory actions of ventral subicular neurons affect the response capacity of the HPA axis.

Adrenal Cortex↗
PubMed1995

Differential expression of protein phosphatase 1 isoforms in mammalian brain.

Rat cDNAs encoding neuronal isoforms of protein phosphatase 1 (PP1) were isolated and their primary structures elucidated. The derived amino acid sequences allowed us to design synthetic C-terminal peptides that were used to raise antibodies. Isoform-specific anti-peptide antibodies against PP1 alpha and PP1 gamma 1 were used to investigate the tissue distribution of PP1 isoforms by immunoblotting. Both isoforms were ubiquitously expressed in mammalian tissues, with the highest levels being observed in brain. Of all neuronal tissues examined, PP1 alpha and PP1 gamma 1 were found to be most abundantly expressed in the striatum. Lesion experiments with kainic acid indicated that both the alpha and the gamma 1 isoforms of protein phosphatase 1 were relatively enriched in the medium-size spiny neurons of the striatum. "In situ" hybridization to rat brain slices using highly sensitive riboprobes also showed PP1 alpha, PP1 beta, and PP1 gamma 1 to be widely expressed in mammalian brain. However, some interesting differences were observed. For example, PP1 alpha and PP1 gamma 1 were found to be expressed in the striatum, where DARPP-32 (dopamine- and cAMP-regulated phosphoprotein, M(r) = 32,000 Da) is also known to be highly expressed. PP1 beta appeared to be relatively less abundant in the same cells, as judged both by "in situ" hybridization and by the apparent absence of PP1 beta clones from the striatal cDNA libraries used.

Amino Acid Sequence↗
PubMed1994

Mu, delta, and kappa opioid receptor mRNA expression in the rat CNS: an in situ hybridization study.

The mu, delta, and kappa opioid receptors are the three main types of opioid receptors found in the central nervous system (CNS) and periphery. These receptors and the peptides with which they interact are important in a number of physiological functions, including analgesia, respiration, and hormonal regulation. This study examines the expression of mu, delta, and kappa receptor mRNAs in the rat brain and spinal cord using in situ hybridization techniques. Tissue sections were hybridized with 35S-labeled cRNA probes to the rat mu (744-1,064 b), delta (304-1,287 b), and kappa (1,351-2,124 b) receptors. Each mRNA demonstrates a distinct anatomical distribution that corresponds well to known receptor binding distributions. Cells expressing mu receptor mRNA are localized in such regions as the olfactory bulb, caudate-putamen, nucleus accumbens, lateral and medial septum, diagonal band of Broca, bed nucleus of the stria terminalis, most thalamic nuclei, hippocampus, amygdala, medial preoptic area, superior and inferior colliculi, central gray, dorsal and median raphe, raphe magnus, locus coeruleus, parabrachial nucleus, pontine and medullary reticular nuclei, nucleus ambiguus, nucleus of the solitary tract, nucleus gracilis and cuneatus, dorsal motor nucleus of vagus, spinal cord, and dorsal root ganglia. Cellular localization of delta receptor mRNA varied from mu or kappa, with expression in such regions as the olfactory bulb, allo- and neocortex, caudate-putamen, nucleus accumbens, olfactory tubercle, ventromedial hypothalamus, hippocampus, amygdala, red nucleus, pontine nuclei, reticulotegmental nucleus, motor and spinal trigeminal, linear nucleus of the medulla, lateral reticular nucleus, spinal cord, and dorsal root ganglia. Cells expressing kappa receptor mRNA demonstrate a third pattern of expression, with cells localized in regions such as the claustrum, endopiriform nucleus, nucleus accumbens, olfactory tubercle, medial preoptic area, bed nucleus of the stria terminalis, amygdala, most hypothalamic nuclei, median eminence, infundibulum, substantia nigra, ventral tegmental area, raphe nuclei, paratrigeminal and spinal trigeminal, nucleus of the solitary tract, spinal cord, and dorsal root ganglia. These findings are discussed in relation to the physiological functions associated with the opioid receptors.

Animals↗
PubMed1994

Differential expression of autoreceptors in the ascending dopamine systems of the human brain.

The tone and regulation of the brain dopaminergic projections are, in part, determined by the presence or absence of dopamine (DA) autoreceptors: rate of DA synthesis and turnover, as well as both pattern and rate of neuronal firing, are modulated by the expression and activity of these autoreceptors. The expression of dopaminergic receptors in the midbrain DA cell groups, presumably reflecting DA autoreceptors, was determined in the brains of the rat, Old World monkey, and human. In the rat, both the substantia nigra (A9) and the ventral tegmental area (A10) appear to express DA autoreceptors. In the monkey and human, however, only the projections arising from the substantia nigra express these receptors; the limbic projections originating in the ventral tegmental area lack this substrate for DA autoregulation. These results indicate that in the human, the nigrostriatal and mesocorticolimbic dopamine systems may be differentially autoregulated.

Animals↗