Norepinephrine-evoked calcium transients in cultured cerebral type 1 astroglia

We have used the CA++ indicator dye fura-2 AM and computerized imaging systems to investigate adrenergic regulation of intracellular calcium in cultured cerebral type 1 astroglia. We have found that norepinephrine (NE) and other adrenergic agonists stimulate increases in intracellular calcium in over 80% of type 1 astroglia tested. A wide range in effective NE concentrations was seen. With sufficient agonist concentrations the calcium response was biphasic, exhibiting an initial sharp peak followed by a sustained calcium elevation. This secondary component was sensitive to reductions in extracellular calcium concentrations and dependent on the continued presence of agonist. Pharmacological studies indicated that astroglial calcium responses were mediated by alpha 1- and alpha 2-adrenergic receptors. At times these two receptor subtypes appeared to underlie calcium responses by the same cells, whereas other cells only responded to stimulation of one or the other subtypes of alpha-adrenergic receptor. Finally, we have also observed spontaneous and agonist-evoked oscillations in astroglial calcium levels. The major findings of these studies indicate that 1) astroglial cells respond to alpha-adrenergic receptor stimulation with increased intracellular calcium, 2) these responses can be mediated by alpha 1-and/or alpha 2-adrenergic receptors, and 3) subpopulations of cerebral type 1 astroglia exist with respect to alpha-adrenergic receptor expression.     

GFAP-positive hippocampal astrocytes in situ respond to glutamatergic neuroligands with increases in [Ca2+]i

It is becoming increasingly clear that astrocytes play very dynamic and interactive roles that are important for the normal functioning of the central nervous system. In culture, astrocytes express many receptors coupled to increases in intracellular calcium ([Ca²⁺]_i). In vivo, it is likely that these receptors are important for the modulation of astrocytic functions such as the uptake of neurotransmitters and ions. Currently, however, very little is known about the expression or stimulation of such astrocytic receptors in vivo. To address this issue, confocal microscopy and calcium sensitive fluorescent dyes were used to examine the dynamic changes in astrocytic [Ca²⁺]_i, within acutely isolated hippocampal slices. Astrocytes were subsequently identified by immunocytochemistry for glial fibrillary acidic protein. In this paper, we present data indicating that hippocampal astrocytes in situ respond to glutamate, kainate, α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), 1-aminocyclopentane-trans-1,3-dicarboxylic acid (t-ACPD), N-methyl-D-aspartate (NMDA), and depolarization with increases in [Ca²⁺]_i. The increases in [Ca²⁺]_i occurred in both the astrocytic cell bodies and the processes. Temporally the changes in [Ca²⁺]_i were very dynamic, and various patterns ranging from sustained elevations to oscillations of [Ca²⁺]_i were observed. Individual astrocytes responded to neuroligands selective for both ionotropic and metabotropic glutamate receptors with increases in [Ca²⁺]_i. These findings indicate that astrocytes in vivo contain glutamatergic receptors coupled to increases in [C²⁺]_i and are able to respond to neuronally released neurotransmitters. (c) 1995 Wiley-Liss, Inc.     

Astroglial cells in vitro are heterogeneous with respect to expression of the alpha 1-adrenergic receptor

A wide variety of approaches have been used to examine the expression of neuroligand receptors by cultured astroglial cells. The results of such studies make it clear that these cells exhibit most, if not all, of the different receptors known to be associated with central neurons. However, it has been more difficult to determine if there are multiple populations of astroglia that can be distinguished on the basis of their complement of neuroligand receptors. To address this question, we established a radioligand binding assay that enabled us to visualize alpha 1-adrenergic receptors (alpha 1-ARs) on immunocytochemically defined neural cells. Saturation, time course, and competition binding experiments determined that 125I-HEAT could be used to identify alpha 1-AR binding sites on immunocytochemically defined astroglial cells. Our results indicate that approximately 66% of cortical polygonal astroglia express detectable numbers of alpha 1-ARs. 3H-thymidine labeling experiments indicate that both dividing and nondividing astroglia exhibit alpha 1-ARs. These results greatly contrast with studies on beta-adrenergic receptor expression (beta-AR), in which 100% of polygonal astroglia express beta-ARs. Process-bearing astroglia also exhibit alpha 1-ARs, which is in marked contrast to the lack of beta-AR expression by these cells. The results presented here suggest that astroglia, like neurons, differ in the receptors they express and therefore may be able to selectively respond to extracellular stimulation.     

Intracellular calcium responses of circadian pacemaker neurons measured with fura-2

The circadian pacemaker in the eye of the mollusk Bulla gouldiana is located within basal retinal neurons (BRNs) that express a circadian rhythm in cell culture. Light and other depolarizing stimuli shift the phase of the pacemaker in the eye through a process that requires extracellular calcium and is blocked by Ni²⁺. To test directly if an influx of Ca²⁺ is present throughout depolarizing treatments that produce phase shifts, dissociated BRNs in cell culture were loaded with a membrane-permeable form of the calcium-sensitive dye fura-2, and then depolarized with elevated levels of extracellular K⁺. Calcium levels in the BRNs remained elevated during treatments with 50 mM K⁺ lasting 1 h, a sufficient duration to phase shift the circadian pacemaker. Lowering extracellular free Ca²⁺ (approx. 1.7 × 10⁻⁷ M) during depolarization blocked the rise in intracellular Ca²⁺, verifying that a Ca²⁺ influx is required. The sustained Ca²⁺ elevation during depolarization was also prevented with 50 mM Ni²⁺, which blocks phase shifts of the rhythm to depolarization, but not with 5 mM Ni²⁺, which does not block phase shifts. The initial rise in [Ca²⁺]_i in response to 50 mM K⁺ was largest on average during the subjective night. The results show that a critical portion of the entrainment pathway persists in pacemaker neurons during cell culture, and that the phase-shifting stimulus may depend on a prolonged Ca²⁺ signal.     

Effect of heat stress on serotonin-2A receptor-mediated intracellular calcium mobilization in rat C6 glioma cells

Summary. This study was conducted to investigate an effect of heat stress at 44°C for 30 min on intracellular Ca²⁺ signaling system and on heat shock protein (HSP)-70 expression. 5-HT-induced Ca²⁺ mobilization was reduced 1, 3 and 6 hrs after heat stress, and recovered to the control level 12 and 24 hrs after heat stress. One hr after heat stress, Ca²⁺ rise was significantly decreased when the cells were stimulated by any concentration of 5-HT. Thrombin-induced Ca²⁺ increase was also markedly reduced 1 hr after heat stress. HSP-70 level was increased 6 and 9 hr after heat stress. In HSP synthesis inhibitor quercetin-treated cells, HSP-70 expression was not enhanced after heat stress, and Ca²⁺ rise in response to 5-HT did not return to the control level. However, the Ca²⁺ rise induced by 5-HT was not restored to the control level after stress in Ac-Asp-Glu-Val-Asp-H (DEVD)-exposed cells while DEVD had little effect on heat stress-induced synthesis of HSP-70. Dexamethasone did not alter the change in HSP-70 expression or Ca²⁺ response after heat stress. These results indicate that heat stress attenuated 5-HT-induced Ca²⁺ mobilization and that HSP-70 expression played an important role in recovery from Ca²⁺ impairment, possibly via protease activity in C6 cells. Received October 16, 1998; accepted December 3, 1999     

Lack of association between suicidal ideation and enhanced platelet 5-HT2A receptor-mediated calcium mobilization in cancer patients with depression.

BACKGROUND: Increased density of 5-HT2A receptors was observed in the platelets of depressive patients with suicidal ideation. Enhanced 5-HT2A receptor-mediated platelet calcium mobilization has been proposed as a biological marker for the pathophysiology of major depression in cancer patients as well as in physically healthy patients. To examine whether depressive cancer patients with suicidal ideation have enhanced 5-HT2A receptor-mediated platelet response compared with those without suicidal ideation, we compared 5-HT-induced platelet calcium mobilization in depressive cancer patients with and without suicidal ideation. METHODS: 5-HT-induced platelet calcium mobilization was examined in 24 cancer patients diagnosed as having major depression according to the DSM-IV criteria. Suicidal ideation was evaluated by the Hamilton Depression Rating Scale and Zung's Self Depression Scale, as well as by the DSM-IV criteria. RESULTS: There was no significant differences in 5-HT-induced platelet calcium response between the depressive cancer patients with (n = 8) and without suicidal ideation (n = 16). 5-HT-induced platelet calcium response was also not significantly associated with the severity of suicidal ideation or with the severity of depression assessed by Hamilton Depression Rating Scale and Zung's Self Depression Scale. CONCLUSIONS: These findings suggest that enhanced 5-HT2A receptor-mediated response was not associated with suicidal ideation in cancer patients with depression.     

Clinical and genetic analysis of three German kindreds with autosomal dominant cerebellar ataxia type I linked to the SCA2 locus

The detailed clinical, electrophysiological and imaging data of three German autosomal dominant cerebellar ataxia (ADCA) families are reported. Linkage to SCA2 was established using microsatellite markers D12S105, D12S1339(1328), D12S1340(1329) yielding a lod score exceeding +3.0 for the combined data. Analysis of the pedigree data provided evidence of anticipation as observed in other neurodegenerative disorders due to polyglutamine expansion encoded by a CAG repeat. This hypothesis was confirmed by the detection of the SCA2-specific pathological protein using the 1C2 monoclonal antibody which selectively recognizes large polyglutamine expansions and the characterization of a CAG expansion in the patients. Clinically, the families were characterized by progressive ataxia of stance, gait and limbs. Saccade velocity was markedly reduced in SCA2. Further oculomotor findings were gaze palsy, impaired smooth pursuit and reduced optokinetic reflex. Dementia and pyramidal tract signs were rather rare, while peripheral involvement (reduced or absent ankle reflexes, fasciculation-like movements, amyotrophy) was a prominent feature. Electrophysiological investigations provided evidence of sensory neuropathy of the axonal type and degeneration of the posterior columns. Imaging studies demonstrated severe shrinkage of brain-stem structures even in early stages of the disease. Received: 10 September 1996 Accepted: 8 December 1996     

Kinin B1 and B2 receptors are overexpressed in the hippocampus of humans with temporal lobe epilepsy

Molecular biology tools have been employed to investigate the participation of peptides in human temporal lobe epilepsy (TLE). Active polypeptides and their receptors have been related to several brain processes, such as inflammation, apoptosis, brain development, K(+) and Ca(2+) channels' activation, cellular growth, and induction of neuronal differentiation. Previous works have shown a neuroprotector effect for kinin B2 receptor and a deleterious, pro-epileptogenic action for kinin B1 receptor in animal models of TLE. The present work was delineated to analyze the kinin B1 and B2 receptors expression in the hippocampus of patients presenting refractory mesial TLE. The hippocampi were removed during the patients surgery in a procedure used for seizure control and compared with tissues obtained after autopsy. Nissl staining was performed to study the tissue morphology and immunohistochemistry, and Western blot was used to compare the distribution and levels of both receptors in the hippocampus. In addition, real time PCR was employed to analyze the gene expression of these receptors. Nissl staining showed sclerotic hippocampi with hilar, granular, and pyramidal cell loss in TLE patients. Immunohistochemistry and Western blot analyses showed increased expression of kinin B1 and B2 receptors but the real-time PCR data demonstrated increased mRNA level only for kinin B2 receptors, when compared with controls. These data show for the first time a relationship between human TLE and the kallikrein-kinin system, confirming ours previous results, obtained from experimental models of epilepsy.     

Illness representations among patients with type 2 diabetes and their partners: relationships with self-management behaviors

OBJECTIVE: There is accumulating evidence to indicate that the illness representations of significant others are important for understanding patients' responses to chronic disease. The aims of the present study were to (a) assess the illness representations of patients with type 2 diabetes and their partners, (b) determine the extent of agreement between patient and partner representations, and (c) examine whether partners' representations mediate the relationships between patients' representations and their prospective self-management behaviors. METHODS: Patients' and partners' representations of diabetes were assessed with the Revised Illness Perception Questionnaire [Moss-Morris R, Weinman J, Petrie K, Horne R, Cameron LD, Buick, D. The revised illness perception questionnaire (IPQ-R). Psychol Health 2002;17:116] at baseline (n=164). Self-management behaviors were assessed 12 months later with self-report measures of physical activity, medication, and a food frequency questionnaire. RESULTS: Patients scored lower on the illness coherence dimension, indicating that they reported a poorer understanding of the condition (t=-2.66, df=163, P=.009) relative to their partners. Patients demonstrated higher scores for personal control than their partners (t=2.01, df=163, P=.046). Mediational analyses indicated that partners' perceived timeline of diabetes partially mediated the relationship between patients' representations and their self-management behaviors including physical activity and dietary intake. In addition, partners' personal control representations partially mediated the relationship between patients' representations and physical activity. CONCLUSION: It was demonstrated that patient-partner dyads generally share similar representations of type 2 diabetes and perceived control over the condition. Furthermore, there was evidence that partners' representations partially mediated the relationships between patients' representations and their prospective self-management behaviors.     

Glutamate receptor mGlu2 and mGlu3 knockout striata are dopamine supersensitive,with elevated D2High receptors and marked supersensitivity to the dopamine agonist (+)PHNO

The finding that the mGlu2/3 metabotropic glutamate receptor agonist, LY404039, improves clinical symptoms in schizophrenia warrants a search for a possible interaction between mGlu2/3 receptors and dopamine D2 receptors. Here, this topic is examined in striatal tissue of mice lacking either mGlu2 or mGlu3 receptor. Such mice are known to be behaviorally supersensitive to dopamine receptor agonists. Therefore, to determine the basis of this dopamine supersensitivity, the proportion of dopamine D2^High receptors was measured in the striata of mGlu2 and mGlu3 receptor knockout mice. The proportion of D2^High receptors was found to be elevated by 220% in the striata of both knockouts. To measure the functional dopamine supersensitivity, the D2 agonist (+)PHNO was used to stimulate the incorporation of GTP‐γ‐S in the striatal homogenates in the presence of drugs that blocked the dopamine D1, D3, and D5 receptors. Compared with control striata, the mGlu2 receptor knockout tissues were 67‐fold more sensitive to (+)PHNO, while the mGlu3 receptor knockout tissues were 17‐fold more sensitive. These data suggest that group II mGlu receptors—mGlu2 receptors in particular—may normally regulate D2 receptors by reducing the proportion of high‐affinity D2 receptors in membranes. Such regulation may contribute to the antipsychotic action of mGlu2/3 receptor agonists. Synapse 63:247–251, 2009. © 2008 Wiley‐Liss, Inc.     

Early-onset neurodegeneration with brain iron accumulation due to PANK2 mutation

Background: Pantothenate kinase-associated neurodegeneration (PKAN) is a neurodegenerative disorder caused by pantothenate kinase (PANK2) gene mutations. Brain magnetic resonance imaging (MRI) typically shows the “eye-of-the-tiger” sign, i.e. bilateral pallidal T2 hypointensity with a small central region of T2-hyperintensity. Aims: To describe clinical and MRI findings of a boy with early-onset neurodegeneration with brain iron accumulation due to PANK2 mutation. Methods: Clinical, neuroradiological and molecular investigations have been performed. Results: At first observation (2 years and 10 months) the boy presented only with developmental delay and toe-walking and isolated T2 hyperintensity within globi pallidi on brain MRI. One year later, small rounded areas of markedly low signal within the globi pallidi on T2∗- weighted images appeared in association with mild dystonia. PANK2 gene homozygous mutation confirmed the diagnosis of PKAN. Conclusions: In young children, PKAN should be suspected also before clinical and neuroradiological picture is fully indicative, to avoid delayed diagnosis of a genetic disease for which therapeutical options could be potentially useful if administered in paucisymptomatic subjects.     

The ability of axons to regenerate their growth cones depends on axonal type and age, and is regulated by calcium, cAMP and ERK

The processes activated at the time of axotomy and leading to the formation of a new growth cone are the first step in regeneration, but are still poorly characterized. We investigated this event in an in vitro model of axotomy performed on dorsal root ganglia and retinal explants. We observed that the dorsal root ganglion axons and retinal ganglion cell axons, which had grown out on a poly d-lysine/laminin substrate at the time of culture preparation greatly differed in their regenerative response after a subsequent in vitro lesion made far from the cell body. The majority of axons of adult dorsal root ganglia but only a small percentage of axons of adult retinal ganglion cells regenerated new growth cones within four hours after in vitro axotomy, though both kinds of axons were growing before the lesion. The depletion of extracellular calcium and the inhibition of extracellular-signal regulated kinase 1,2 (ERK) and protein kinase A (PKA) at the time of injury significantly impaired the capacity of dorsal root ganglia axons to re-initiate growth cones without affecting growth cone motility. Pharmacological treatments directed at increasing the level of cAMP promoted growth cone regeneration in adult retinal ganglion cell axons in spite of the low regenerative potential exhibited in normal conditions. Understanding the cellular mechanisms activated at the time of lesion and leading to the formation of a new growth cone is necessary for devising treatments aimed at enhancing the regenerative response of injured axons.     

Differential ability of tachykinin NK-1 and NK-2 agonists to produce scratching and grooming behaviours in mice

Potent and selective NK-1 and NK-2 agonists as well as compounds with lower selectivity and affinity for NK-1 binding sites were compared in their ability to produce scratching and grooming behaviours when injected intracerebroventricularly in mice. Septide, an agonist with a low affinity for NK-1 binding sites, [Sar⁹, Met(O₂)¹¹]SP and to a lesser extent [Pro⁹]SP, two potent and selective NK-1 agonists were the most effective drugs in stimulating these behaviours. Only high doses of [Apa^9,10]SP and [Lys⁵, Tyr⁷, Pro⁸]NKA(4–10), two agonists with low affinity for NK-1 binding sites, produced scratching and grooming responses. Similarly, only high doses of [Lys⁵, MeLeu⁹, NLe¹⁰]NKA(4–10), a potent NK-2 agonist, produced grooming behaviour. When coinjected with the endopeptidase enzyme inhibitor phosphoramidon, the effects of [Apa^9,10]SP, [Lys⁵, Tyr⁷, Pro⁸]NKA(4–10) and [Pro⁹]SP were markedly enhanced. Analyses of the potency of the different agents to displace ³H-SP binding in mouse subcortical structures revealed that the affinities of the agonists for NK-1 receptors are similar to those previously reported in rat brain. The efficacy of the agonists at producing behavioural responses was not equivalent to their potency to bind to central NK-1 receptors. These findings therefore suggest that a stimulation of NK-1 but also non classical NK-1 receptors are involved in the induction of scratching and grooming behaviours.     

Obesity and type 2 diabetes in rats are associated with altered brain glycogen and amino-acid homeostasis

Obesity and type 2 diabetes have reached epidemic proportions; however, scarce information about how these metabolic syndromes influence brain energy and neurotransmitter homeostasis exist. The objective of this study was to elucidate how brain glycogen and neurotransmitter homeostasis are affected by these conditions. [1-¹³C]glucose was administered to Zucker obese (ZO) and Zucker diabetic fatty (ZDF) rats. Sprague–Dawley (SprD), Zucker lean (ZL), and ZDF lean rats were used as controls. Several brain regions were analyzed for glycogen levels along with ¹³C-labeling and content of glutamate, glutamine, GABA, aspartate, and alanine. Blood glucose concentrations and ¹³C enrichment were determined. ¹³C-labeling in glutamate was lower in ZO and ZDF rats in comparison with the controls. The molecular carbon labeling (MCL) ratio between alanine and glutamate was higher in the ZDF rats. The MCL ratios of glutamine and glutamate were decreased in the cerebellum of the ZO and the ZDF rats. Glycogen levels were also lower in this region. These results suggest that the obese and type 2 diabetic models were associated with lower brain glucose metabolism. Glucose metabolism through the TCA cycle was more decreased than glycolytic activity. Furthermore, reduced glutamate–glutamine cycling was also observed in the obese and type 2 diabetic states.     

LSD and DOB: interaction with 5-HT2A receptors to inhibit NMDA receptor-mediated transmission in the rat prefrontal cortex

Both the phenethylamine hallucinogen (-)-1-2, 5-dimethoxy-4-bromophenyl-2-aminopropane (DOB), a selective serotonin 5-HT2A,2C receptor agonist, and the indoleamine hallucinogen D-lysergic acid diethylamide (LSD, which binds to 5-HT1A, 1B, 1D, 1E, 1F, 2A, 2C, 5, 6, 7, dopamine D1 and D2, and alpha1 and alpha2 adrenergic receptors), but not their non-hallucinogenic congeners, inhibited N-methyl-D-aspartate (NMDA)-induced inward current and NMDA receptor-mediated synaptic responses evoked by electrical stimulation of the forceps minor in pyramidal cells of the prefrontal cortical slices. The inhibitory effect of hallucinogens was mimicked by 5-HT in the presence of selective 5-HT1A and 5-HT3 receptor antagonists. The inhibitory action of DOB, LSD and 5-HT on the NMDA transmission was blocked by the 5-HT2A receptor antagonists R-(+)-alpha-(2, 3-dimethoxyphenil)-1-[4-fluorophenylethyl]-4-piperidineme thanol (M100907) and ketanserin. However, at low concentrations, when both LSD and DOB by themselves only partially depressed the NMDA response, they blocked the inhibitory effect of 5-HT, suggesting a partial agonist action. Whereas N-(4-aminobutyl)-5-chloro-2-naphthalenesulphonamide (W-7, a calmodulin antagonist) and N-[2-[[[3-(4'-chlorophenyl)- 2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4'-methoxy-b enzenesulphonamide phosphate (KN-93, a Ca2+/CaM-KII inhibitor), but not the negative control 2-[N-4'methoxybenzenesulphonyl]amino-N-(4'-chlorophenyl)-2-propeny l-N -methylbenzylamine phosphate (KN-92), blocked the inhibitory action of LSD and DOB, the selective protein kinase C inhibitor chelerythrine was without any effect. We conclude that phenethylamine and indoleamine hallucinogens may exert their hallucinogenic effect by interacting with 5-HT2A receptors via a Ca2+/CaM-KII-dependent signal transduction pathway as partial agonists and modulating the NMDA receptors-mediated sensory, perceptual, affective and cognitive processes.     

Plasma homocysteine levels are independently associated with the severity of peripheral polyneuropathy in type 2 diabetic subjects

Peripheral polyneuropathy (PN) is a frequent complication of diabetes. However, mechanisms underlying the development of PN are multifactorial and not well understood. Our aim was to examine the association of plasma homocysteine (Hcy) with the prevalence and grade of peripheral PN in patients with type 2 diabetes (T2DM). We studied a cohort of 196 subjects with T2DM classified according to the grade of PN (Neuropathy Disability Score, NDS). Subjects with the highest grade of PN were older and had significantly increased levels of creatinine, microalbuminuria, HbA1c, and plasma Hcy compared to the other two groups. The differences in plasma Hcy values were maintained after correcting for confounding factors. Plasma Hcy, HbA1c, duration of diabetes, and age were predictors of the grade of PN. In conclusion, for each increase of 1 μmol in plasma Hcy there was a 23% increase of the risk of diabetic PN evaluated by NDS. Moreover, the grade of PN was predicted by plasma Hcy and HbA1c values, age and duration of diabetes. Further prospective studies should be conducted to confirm the association of plasma Hcy levels with the grade of PN in subjects with T2DM.     

Spinocerebellar ataxia type 2 with Levodopa-responsive parkinsonism culminating in motor neuron disease.

We describe an exceptional spinocerebellar ataxia type 2 (SCA2) phenotype combining cerebellar ataxia, levodopa-responsive parkinsonism, and motor neuron symptoms. We conclude that motor neuron symptoms and signs may be a striking manifestation in SCA2, masking pre-existing cerebellar and extrapyramidal semeiology.     

Subpopulations of vomeronasal sensory neurons with coordinated coexpression of type 2 vomeronasal receptor genes are differentially dependent on Vmn2r1

The mouse vomeronasal organ is specialized in the detection of pheromones. Vomeronasal sensory neurons (VSNs) express chemosensory receptors of two large gene repertoires, V1R and V2R, which encode G‐protein‐coupled receptors. Phylogenetically, four families of V2R genes can be discerned as follows: A, B, C, and D. VSNs located in the basal layer of the vomeronasal epithelium coordinately coexpress V2R genes from two families: Approximately half of basal VSNs coexpress Vmn2r1 of family C with a single V2R gene of family A8‐10, B, or D (‘C1 type of V2Rs’), and the other half coexpress Vmn2r2 through Vmn2r7 of family C with a single V2R gene of family A1‐6 (‘C2 type V2Rs’). The regulatory mechanisms of the coordinated coexpression of V2Rs from two families remain poorly understood. Here, we have generated two mouse strains carrying a knockout mutation in Vmn2r1 by gene targeting in embryonic stem cells. These mutations cause a differential decrease in the numbers of VSNs expressing a given C1 type of V2R. There is no compensatory expression of Vmn2r2 through Vmn2r7. VSN axons coalesce into glomeruli in the appropriate region of the accessory olfactory bulb in the absence of Vmn2r1. Gene expression profiling by NanoString reveals a differential and graded decrease in the expression levels across C1 type of V2Rs. There is no change in the expression levels of C2 type of V2Rs, with two exceptions that we reclassified as C1 type. Thus, there appears to be a fixed probability of gene choice for a given C2 type of V2R.     

Characterization of binding of3H-SCH 23390 to dopamine D-1 receptors. Correlation to other D-1 and D-2 measures and effect of selective lesions

Summary The binding of³H-SCH 23390 to membranes from rat and mouse brain tissue has been investigated. The binding was saturable and reached equilibrium after 60 minutes. Nonspecific binding was low. Association and dissociation rates were Mg⁺⁺-sensitive. In almost all respects the binding of³H-SCH 23390 was comparable to the binding of³H-piflutixol and³H-cis(Z)-flupentixol.The density of binding sites in striatum was greater than in limbic structures which in turn was greater than in frontal cortex. The density of binding sites in these structures were comparable with those of³H-piflutixol and³H-cis(Z)-flupenthixol, 2–3 times higher than the D-2-receptor density. Whereas an increase was seen in³H-spiperone binding after unilateral 6-OHDA lesion no changes were seen in³H-SCH 23390 binding. The binding was decreased approximately 72% 3 weeks after unilateral kainic acid lesion whereas that of³H-spiperone was only decreased 56%. Finally, the affinities of neuroleptics to the³H-SCH 23390-binding sites correlated to the affinities to³H-piflutixol-binding sites and to the effects on DA-sensitive adenylate cyclase.Agonist competition curves were shallow and the data best fit a two-site model composed of a high and a low affinity component.Thus,³H-SCH 23390 is regarded as a highly selective ligand for brain dopamine D-1 receptorsin vitro.