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S J Watson

Publications and source records attributed to S J Watson.

At least 145 records · Page 8Linked to original sources
PubMed1994

Glucocorticoid regulation of hippocampal oxytocin receptor binding.

The effects of glucocorticoid hormones on oxytocin receptors in rat hippocampus were investigated. Oxytocin receptor autoradiography (using 0.1 and 1.2 nM concentrations of [125I]OVTA) revealed a significant (P < 0.02) decrease in oxytocin receptor binding in adrenalectomized animals 7 days after the surgery. Corticosterone replacement at the time of adrenalectomy prevented the decrease in oxytocin binding. The findings were significant in hippocampus and subiculum. These findings suggest regulation of oxytocin receptors, and possibly oxytocin-regulated behaviors by glucocorticoids.

Adrenalectomy↗
PubMed1994

Primary structure and functional expression of a guinea pig kappa opioid (dynorphin) receptor.

A full-length cDNA encoding the guinea pig kappa opioid (dynorphin) receptor has been isolated. The deduced protein contains 380 aa and seven hydrophobic alpha-helices characteristic of the G protein-coupled receptors. This receptor is 90% identical to the mouse and rat kappa receptors, with the greatest level of divergence in the N-terminal region. When expressed in COS-7 cells, the receptor displays high affinity and stereospecificity toward dynorphin peptides and other kappa-selective opioid ligands such as U50, 488. It does not bind the mu- and delta-selective opioid ligands. The expressed receptor is functionally coupled to G protein(s) to inhibit adenylyl cyclase and Ca2+ channels. The guinea pig kappa receptor mRNA is expressed in many brain areas, including the cerebellum, a pattern that agrees well with autoradiographic maps of classical guinea pig kappa binding sites. Species differences in the pharmacology and mRNA distribution between the cloned guinea pig and rat kappa receptors may be worthy of further examination.

Amino Acid Sequence↗
PubMed1994

mu-Opioid receptor mRNA expression in the rat CNS: comparison to mu-receptor binding.

The distribution of cells expressing mu-receptor mRNA and mu-receptor binding sites were compared in brain and spinal cord tissue sections using a combination of in situ hybridization and receptor autoradiographic techniques. mu-Receptor mRNA was visualized with a 35S-labeled cRNA probe directed to transmembrane III-VI of the rat mu-receptor, while mu-receptor binding sites were labeled with the mu-selective ligand [3H]DAMGO. A high correspondence between the mu-receptor mRNA and receptor binding distributions was observed in the nucleus of the accessory olfactory bulb, anterior olfactory nuclei, striatal patches of the nucleus accumbens and caudate-putamen, endopiriform nucleus, claustrum, diagonal band of Broca, globus pallidus, ventral pallidum, bed nucleus of stria terminalis, most thalamic nuclei, medial and posteriocortical medial amygdala, lateral, dorsomedial, posterior and mammillary nuclei of the hypothalamus, presubiculum, subiculum, rostral interpeduncular nucleus, median raphe, inferior colliculus, parabrachial nucleus, locus coeruleus, central grey, nucleus ambiguus, nucleus of the solitary tract, nucleus gracilis, nucleus cuneatus, and the dorsal motor nucleus of vagus. Differences in mu-receptor mRNA and receptor binding distributions were observed in several regions, including the olfactory bulb, cortex, hippocampus, superior colliculus, spinal trigeminal nucleus, cochlear nucleus and spinal cord, and may be due to mu-receptor transport to presynaptic terminals.

Animals↗
PubMed1994

Increased evening activation of the hypothalamic-pituitary-adrenal axis in depressed patients.

OBJECTIVE: To determine whether depressed patients demonstrate hypothalamic-pituitary-adrenal (HPA) axis activation during the late afternoon and evening, a time when the HPA axis is usually quiescent in normal subjects. METHODS: We administered metyrapone, an 11-beta-hydroxylase inhibitor of cortisol synthesis, to normal controls and depressed patients between 4 and 10 PM. Metyrapone blockade of cortisol secretion would amplify any HPA axis secretion. RESULTS: In 10 normal control subjects, administration of metyrapone lowered plasma cortisol levels to a mean of 36 nmol/L. No rebound corticotropin or beta-endorphin secretion was seen in these normal controls between 4 and 10 PM, supporting the existence of a period of minimal endogenous corticotropin releasing factor drive. Compared with a group of placebo-treated depressed patients (n = 10), metyrapone-treated depressed subjects (n = 17) had significantly decreased plasma cortisol concentrations. However, in contrast to normal controls treated with metyrapone, metyrapone-treated depressed patients demonstrated rebound corticotroph secretion, particularly between 7:30 and 10 PM (P = .036 for patients vs normal controls for beta-endorphin secretion from 4:30 to 10 PM). CONCLUSION: These data support the hypothesis of increased corticotropin releasing factor drive in the evening in depressed subjects and are in agreement with the longstanding observation of "early escape" from dexamethasone suppression between 4 and 11 PM in depressed patients.

Adrenocorticotropic Hormone↗
PubMed1994

The effects of haloperidol on dopamine receptor gene expression.

Haloperidol is a widely prescribed antipsychotic that acts as a dopamine D2 receptor antagonist. Chronic administration of haloperidol leads to an increase in striatal D2 receptor binding; however, studies examining striatal D2 receptor mRNA after haloperidol treatment report inconsistent results. This study examines the effects of haloperidol on dopaminoceptive striatal neurons, as well as dopamine D2 containing striatal inputs. Rats were injected subcutaneously with 2 mg/kg haloperidol twice daily for 7 days. A significant (36%) increase in D2 mRNA was observed in the anterior cingulate cortex. However, no changes were observed in the amounts of D1, D2, D3 mRNA, or D2 heteronuclear RNA (hnRNA) in the striatum or in the levels of D2 mRNA and hnRNA in the substantia nigra and ventral tegmental area. Thus, increased striatal D2 binding after haloperidol treatment may not be the result of altered D2 gene activity in the striatum or midbrain, but could result from an increase in D2 mRNA in cingulate corticostriatal neurons and/or a longer half-life for the D2 receptor protein in striatal neurons. Striatal proenkephalin mRNA increased significantly in the caudate-putamen (45%), nucleus accumbens (36%), and the olfactory tubercle (27%) while prodynorphin mRNA remained unaltered after haloperidol treatment. Since D2 receptor mRNA is generally colocalized with proenkephalin mRNA in striatal neurons, these results demonstrate what is likely a selective cellular increase in proenkephalin mRNA without a parallel increase in D2 mRNA.

Animals↗
PubMed1994

Kappa 1 receptor mRNA distribution in the rat CNS: comparison to kappa receptor binding and prodynorphin mRNA.

Three opioid receptor types have been identified in the CNS and periphery that are referred to as mu, delta, and kappa. The present study examines the mRNA distribution of the kappa 1 receptor in the rat brain and compares it to the distribution of kappa receptor-binding sites and prodynorphin mRNA using a combination of in situ hybridization and receptor autoradiographic techniques. kappa 1 receptor mRNA was localized with a cRNA probe generated with a BamHI-HindIII cDNA fragment of the rat kappa 1 receptor and corresponds to the last 45 bp of the protein coding region and 728 nucleotides of the 3' untranslated region. Prodynorphin mRNA was localized with a cRNA probe corresponding to a 733-bp BamHI-HincII fragment of prodynorphin. kappa receptor-binding sites were labeled in one of two ways: [3H]U69,593 or [3H]bremazocine in the presence of a 300-fold excess of DAMGO and DPDPE. A high degree of correspondence between the kappa 1 receptor mRNA and kappa receptor binding was observed in several brain regions, including the endopiriform nucleus, claustrum, nucleus accumbens, olfactory tubercle, bed nucleus of the stria terminalis, medial preoptic area, paraventricular, supraoptic, suprachiasmatic, dorsomedial and ventromedial hypothalamic nuclei, basolateral, medial and cortical amygdaloid nuclei, midline thalamic nuclei, periaqueductal grey, parabrachial nucleus, locus coeruleus, and the nucleus of the solitary tract. Differences in the localization of kappa 1 receptor mRNA and binding and the relationship between the distribution of kappa 1 receptor and prodynorphin mRNAs are discussed.

Animals↗
PubMed1994

Cloning and expression of the A2a adenosine receptor from guinea pig brain.

A full-length complementary DNA (cDNA) clone encoding the guinea pig brain A2 adenosine receptor has been isolated by polymerase chain reaction (PCR) and low-stringency-hybridization screening of a guinea pig brain cDNA library. This cDNA contains a long open reading frame encoding a 409-amino acid-residue protein which is highly homologous to the A2 adenosine receptors previously cloned from other species. Hydrophobicity analysis of the deduced protein sequence reveals seven hydrophobic regions, characteristic of a member of the G-protein-coupled receptor superfamily. Radioligand binding assay and functional (GTPase and cAMP) assays of the receptor, transiently expressed in mammalian cells, demonstrate typical characteristics of the A2 type adenosine receptor. The messenger RNA (mRNA) of this A2 receptor is found in the brain, heart, kidney and spleen. Receptor autoradiography with [3H]CGS21680, a specific A2 agonist, and in situ hybridization with A2 cRNA probe in guinea pig brain indicate that the receptor is expressed exclusively in the caudate nucleus. The pharmacological profile and anatomical distribution of this receptor indicate that it is of the A2a subtype. This work represents the first cloning of an A2a receptor in a rodent species, offers a complete pharmacological characterization of the receptor and provides an anatomical comparison between binding profile and gene expression of the receptor.

Amino Acid Sequence↗
PubMed1994

Cloning and characterization of a pharmacologically distinct A1 adenosine receptor from guinea pig brain.

Three full-length cDNA clones encoding the guinea pig A1 adenosine receptor have been isolated by polymerase chain reaction (PCR) and low-stringency hybridization screening of a guinea pig brain cDNA library. These three cDNAs, though differing in their 5' untranslated regions, contain the same open reading frame encoding a 326 amino acid residue protein with seven hydrophobic alpha-helices long enough to form the transmembrane domains, suggesting that it belongs to the G protein-coupled receptor superfamily. This protein is highly homologous to the A1 adenosine receptors previously cloned from other species. Pharmacological characterization of this receptor transiently expressed in mammalian cells demonstrates that, despite its high homology to A1 adenosine receptors of other species, the guinea pig A1 adenosine receptor displays a unique pharmacological profile: high affinity for the A1-selective antagonist CPX, yet very low affinity for some A1-selective agonists such as CCPA, CHA and R-PIA. Northern blotting for different guinea pig tissues and in situ hybridization for guinea pig brain sections reveal an abundant and broad distribution of mRNA of this A1 subtype receptor in the brain.

Adenosine↗
PubMed1994

Differential distribution of messenger RNAs for cathepsins B, L and S in adult rat brain: an in situ hybridization study.

The cysteine lysosomal proteases comprise a large family of highly conserved enzymes which are essential for intracellular protein turnover. These proteases are very efficient in their ability to degrade components of the extracellular matrix, and have been implicated in processes of cell growth, malignant transformation and inflammation. There is also a growing body of evidence for their involvement in the metabolism of the amyloid precursor protein. The production of insoluble beta A4 amyloid peptide is thought to be one of the key events that lead to the development of Alzheimer's pathology. To see the physiological role these enzymes play in the brain, we studied the relative abundance and distribution of the messenger RNAs for three lysosomal cysteine proteases, cathepsins B and L and cathepsin S, by in situ hybridization histochemistry in rat brain. All three enzymes are capable of degrading components of the extracellular matrix but they have different substrate preferences and resistances to neutral pH. We found that the mRNAs for cathepsins B, L, and S have different expression patterns in brain. Cathepsin B mRNA shows the highest level of expression. It has a wide distribution, and is preferentially expressed in neurons. The expression patterns of cathepsin B and cathepsin L mRNA overlap in many brain regions; in some areas they complement each other. Cathepsin B and L mRNAs are highly expressed in the choroid plexus, a structure that is instrumental in brain development. Both transcripts are also abundant in the neuropeptide synthesizing hypothalamic nuclei. Cathepsin S mRNA has wide expression pattern throughout brain, in grey and white matter. A great number of cells that express cathepsin S have microglial morphology. Regions that are known to contain the highest amounts of the amyloid precursor protein express highest levels of cathepsin B and cathepsin L mRNA. Also, all three transcripts are highly represented in regions that are most prone to degeneration in Alzheimer's disease. These results suggest a role for these lysosomal hydrolases released from degenerating cells in the development of Alzheimer's pathology.

Animals↗
PubMed1994

Regulation of hippocampal 5-HT1A receptor gene expression by dexamethasone.

The effect of dexamethasone, a selective GR agonist, on hippocampal, 5-HT1A receptor mRNA expression and 5-HT1A binding was examined using in situ hybridization histochemistry and in vitro receptor autoradiography. One week after adrenalectomy, both 5-HT1A receptor mRNA expression and 5-HT1A binding were increased throughout the hippocampus. Administration of dexamethasone at the time of adrenalectomy significantly attenuated the increases in 5-HT1A mRNA expression in all hippocampal subfields (p < .05, Fisher Test), although 5-HT1A mRNA levels remained significantly higher than sham levels in all subfields with the exception of CA1. However, 5-HT1A binding levels were responsive to dexamethasone administration only within particular hippocampal subfields, CA1, and dentate gyrus. We conclude that GR occupation negatively regulates 5-HT1A receptor mRNA expression within the hippocampus and that 5-HT1A receptor sites are most sensitive to modulation in those hippocampal subfields expressing higher levels of GR receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Dopamine receptor gene expression in the human medial temporal lobe.

The distributions of the messenger RNA molecules encoding the five known dopamine receptors have been determined in the medial temporal lobe of postmortem human brain. All five receptor mRNAs are present in temporal lobe structures, although their distributions are heterogeneous. The D1-like receptors, D1 and D5, have strikingly dissimilar distributions. D1 receptor mRNA is abundant in temporal neocortex but is rare elsewhere. D5 receptor message, however, is seen in the hippocampus, subicular complex, and in temporal cortex. The D2-like receptors have similar distributions: D2, D3, and D4 receptor mRNAs are all identifiable in the hippocampal formation and in the cortical regions of the medial temporal lobe. Distinct patterns of relative regional concentrations for each message are observed, however, suggesting a neuroanatomical substrate for potential differences in dopaminergic regulation within discrete regions of the medial temporal lobe. These results provide a description of the distribution of these receptor mRNAs in normal humans and suggest multiple levels of complexity as well as regulation of the medial temporal lobe dopamine projection.

Adult↗
PubMed1994

Involvement of the bed nucleus of the stria terminalis in tonic regulation of paraventricular hypothalamic CRH and AVP mRNA expression.

The bed nucleus of the stria terminalis (BNST) occupies a central position in pathways regulating hypothalamo-pituitary-adrenocortical (HPA) stress regulation. The potential role of the BNST in tonic neural control of HPA function was assessed by examining effects of selective BNST lesions on expression of ACTH secretagogues in HPA-integrative neurons of the medial parvocellular paraventricular nucleus. Anterior BNST lesions (ABN) involved major portions of the anteromedial, anterolateral, ventromedial, ventrolateral, dorsolateral and juxtacapsular subnuclei. These lesions resulted in significant (30%) decreases in corticotropin-releasing hormone (CRH) mRNA expression across the rostrocaudal extent of the medial parvocellular PVN, with no accompanying changes in basal arginine vasopressin (AVP) mRNA levels. Posterior BNST (PBN) lesions involved large but subtotal damage to the posterior intermediate, posterior medial, posterior lateral and preoptic subnuclei; these lesions resulted in small but significant changes in CRH mRNA and slight increases in number of AVP mRNA-producing parvocellular neurons. PBN effects on CRH mRNA expression were most pronounced at the caudal extent of the medial parvocellular zone, suggesting a topographic input from the posterior BNST to the PVN that is only partially compromised by PBN lesions. Analysis of individual cases revealed a correlation between damage of the anterolateral BNST and decreased CRH mRNA levels, and damage of the posterior intermediate and/or posterior medial BNST and increased CRH mRNA levels. The results suggest differential BNST input into HPA regulation, perhaps reflecting the diversity of limbic input into the BNST region.

Adrenocorticotropic Hormone↗
PubMed1993

Cloning and pharmacological characterization of a rat kappa opioid receptor.

A full-length cDNA was isolated from a rat striatal library by using low-stringency screening with two PCR fragments, one spanning transmembrane domains 3-6 of the mouse delta opioid receptor and the other unidentified but homologous to the mouse delta receptor from rat brain. The novel cDNA had a long open reading frame encoding a protein of 380 residues with 59% identity to the mouse delta receptor and topography consistent with a seven-helix guanine nucleotide-binding protein-coupled receptor. COS-1 cells transfected with the coding region of this clone showed high-affinity binding to kappa opioid receptor-selective ligands such as dynorphin A and U-50,488 and also nonselective opioid ligands such as bremazocine, ethylketocyclazocine, and naloxone. Not bound at all (or bound with low affinity) were dynorphin A-(2-13), enantiomers of naloxone and levophanol [i.e., (+)-naloxone and dextrorphan], and selective mu and delta opioid receptor ligands. Activation of the expressed receptor by kappa receptor agonists led to inhibition of cAMP. Finally, in situ hybridization revealed a mRNA distribution in rat brain that corresponded well to the distribution of binding sites labeled with kappa-selective ligands. These observations indicate that we have cloned a cDNA encoding a rat kappa receptor of the kappa 1 subtype.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1993

Effects of cocaine on dopamine receptor gene expression: a study in the postmortem human brain.

The effects of chronic cocaine exposure on dopamine D1 and D2 receptor gene expression in the human brain were studied in postmortem samples from chronic cocaine abusing and matched control subjects. Using in situ hybridization of receptor autoradiography to examine messenger ribonucleic acid (RNA) and binding sites, respectively, neither D1 nor D2 receptor expression was found to be changed in the nucleus accumbens, caudate, putamen, or substantia nigra of the cocaine-exposed subjects. Although chronic cocaine exposure can produce alterations in dopaminergic neurotransmission, sustained compensatory changes in dopamine receptor expression do not appear to occur in the human.

Adult↗
PubMed1993

A bacterially expressed mineralocorticoid receptor is associated in vitro with the 90-kilodalton heat shock protein and shows typical hormone- and DNA-binding characteristics.

A recombinant system was developed for generation of steroid-receptor complexes in vitro. The DNA- and steroid-binding domains of the rat mineralocorticoid receptor were expressed in Escherichia coli as a fusion protein with glutathione S-transferase. The identity of the expressed recombinant protein was confirmed by Western blot analysis. Protein preparations purified by affinity chromatography, avoiding the use of detergents or high ionic strength buffers, exhibited negligible steroid binding. However, after incubation of these preparations with rabbit reticulocyte lysate, known to promote the association of isolated steroid receptors with heat shock proteins, the [3H]aldosterone-binding activity gradually increased. This temperature-dependent effect reached a maximum after 1 h at 30 degrees C and was favored by ATP supplementation (Bmax = 22 +/- 3 pmol/mg of protein). The apparent Kd value for aldosterone (0.6 +/- 0.2 nM) and the steroid-binding specificity of the recombinant protein were in accordance with those reported for the native mineralocorticoid receptor. The sedimentation and DNA-cellulose-binding characteristics of the radioactive complexes were also in agreement with those reported for the native heteromeric receptor. Complexes sedimented at 8.9 +/- 0.2 or 4.2 +/- 0.2 S in sucrose gradients containing 20 mM sodium molybdate or 0.4 M KCl, respectively. Monoclonal antibody 8D3 against the 90-kDa heat shock protein (hsp90) was able to bind to the 8.9S complexes, increasing its sedimentation coefficient. Treatment of the complexes with 100 mM sodium thiocyanate, known to activate the native receptor to a DNA-binding state, caused a 79% increase in DNA-cellulose binding over the control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗