Spine and spinal cord vascular malformations: pictorial essay.
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Arteriovenous Fistula↗
Biomedical subjects
J L Gariépy
Publications and source records attributed to J L Gariépy.
D1 dopamine receptors and the reversal of isolation-induced behaviors in mice.
In a previous study, it was demonstrated that the high rates of social reactivity exhibited by isolated male mice in a dyadic encounter were mediated, at least in part, by an increased sensitivity of the D1 dopamine receptors. The present research was guided by the hypothesis that the behavioral effects of isolation are reversible, and that changes in dopaminergic function support this reversibility. To this end, mice selectively bred for high and low levels of aggression were reared in isolation from weaning (21 days) to puberty (45 days), at which point they were either assigned to groups or left in isolation until day 69. By comparison to the continuous isolation condition, mice that eventually formed groups exhibited significantly less reactivity in a dyadic test conducted on day 69, showed a reduced response to dihydrexidine (DHX), and a decreased density of D1 dopamine receptors. This experiment provided evidence for the plasticity of the neurobiological system supporting reactive responses, and confirmed the view that its functional organization is open to experientially-induced changes.
Animals↗
D2-like dopamine receptor mediation of social-emotional reactivity in a mouse model of anxiety: strain and experience effects.
We examined the effects of the D2-like dopamine receptor agonist quinpirole on social-emotional reactivity in two inbred mouse strains. An important objective of this study was to determine whether these effects could be modulated by differential housing conditions (i.e., isolation versus group housing). Moreover, as motor activity is an important control for the assessment of drug effects on emotional behavior, the effects of quinpirole were tested in two inbred mouse strains (A/J and C57BL/6J) low and high in motor activity, respectively. Levels of emotional reactivity were assessed in response to mild social stimulation provided by a nonaggressive conspecific. Quinpirole increased stationary forms of reactivity (i.e., startle, kicking, defensive posture, vocalization) in both isolated and group-housed A/J mice. This effect was more pronounced and observed at lower doses in isolated than in group-housed A/J mice. Quinpirole also induced jump behavior in isolated but not group-housed A/J mice. The shift to the left in the dose-response curve of quinpirole in isolated A/J mice indicated that D2-like dopamine receptor functions can be altered by social experience. Quinpirole only marginally increased stationary and locomotor reactivity (i.e., jump) in isolated C57BL/6J mice, whereas it markedly reduced motor activity in group-housed mice of this strain. The investigation of emotional reactivity within a social context and using strains that differ in motor activity permitted the effects of drugs on emotional reactivity to be dissociated from the effects on motor activity. Given that social-emotional reactivity was elicited by what typically should have been mild and nonthreatening stimuli, this model may be highly relevant to understanding the neurobiology of anxiety. Finally, these data support an important role for dopamine in the mediation of social-emotional reactivity.
Animals↗
Effects of the putative dopamine D3 receptor antagonist PNU 99194A on motor behavior and emotional reactivity in C57BL/6J mice.
Due to the regional expression of D3 dopamine receptors in limbic areas of the brain, there has been considerable interest in the potential role of this receptor subtype in mediating emotional behavior. Previous studies in habituated rats have shown that the putative dopamine D3 receptor antagonist 5,6-dimethoxy-2-(di-n-propylamino)indan (PNU 99194A) increased locomotor behavior. The present study examined the effects PNU 99194A on motor and emotional behaviors in C57BL/6J mice. Motor behavior was assessed in both habituated and nonhabituated mice. Emotional behavior was assessed using the elevated plus-maze and a social context involving an isolated C57BL/6J mouse and a nonaggressive conspecific. In mice habituated to the activity chamber prior to drug administration, PNU 99194A increased locomotion and rearing at lower doses (5, 10 mg/kg) whereas higher doses (20, 30 mg/kg) reduced these behaviors early in the test session. Thigmotaxis was increased independently of the effects on motor behavior. In mice exposed to the activity chamber for the first time, PNU 99194A produced a weak motor activation at lower doses and an initial decrease in motor behavior at higher doses that was followed by an increase in locomotion later in the test session. PNU 99194A had no systematic effects on activity in the elevated plus-maze, but dose-dependently increased flight reactivity in the social reactivity paradigm. These and previous findings raise questions about the role of dopamine D3 receptors in mediating motor behavior and emotional reactivity as well as the pharmacology of this putative dopamine D3 receptor antagonist.
Animals↗
D1 dopamine receptor mediation of social and nonsocial emotional reactivity in mice: effects of housing and strain difference in motor activity.
The study examined the effects of isolation housing and the role of D1 dopamine receptors on isolation-induced social and nonsocial (acoustic startle) reactivity in mice high (C57BL/6) and low (A) in motor activity. Isolation housing had no effect on acoustic startle but increased strain-specific forms of social reactivity. The D1 agonist dihydrexidine (DHX) increased acoustic startle in isolated mice of both strains, but this effect was more pronounced in C57BL/6 mice. In this strain, DHX and the D1 agonist SKF-81297 increased locomotor forms of social reactivity (e.g., escape, jump), whereas the D1 antagonist SCH-23390 increased stationary reactivity (e.g., freezing). In A mice, DHX and SKF-81297 increased and decreased stationary reactivity, respectively, whereas SCH-23390 had no effect on these behaviors. Administration of SKF-81297 after pretreatment with SCH-23390 or the D2 antagonist sulpiride confirmed the importance of D1 receptors in mediating specific forms of social reactivity in C57BL/6 mice. These results suggest an important relationship between social reactivity and motor activity and an important, albeit strain-dependent, role for D1 receptors in mediating specific emotional behaviors.
Animals↗
Residents' corner. Answer to case of the month #41. Mature ovarian cystic teratoma.
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Adult↗
Rearing conditions alter social reactivity and D1 dopamine receptors in high- and low-aggressive mice.
As a result of selective breeding, NC900 mice exhibit isolation-induced attacks in a social interaction test, whereas NC100 mice do not attack but freeze instead. Administration of the D1 receptor agonist dihydrexidine was previously shown to reduce aggression in NC900 mice and nonagonistic approaches in NC100 mice. This resulted from induction of a marked social reactivity in both selected lines. Because isolation rearing also induces social reactivity, the present experiment was designed to test the hypothesis that D1 dopamine receptors mediate isolation-induced social reactivity. Isolation was expected to potentiate the effects of a D1 agonist and to increase D1 dopamine receptor density. Thus, isolated and group-reared mice were administered dihydrexidine, and their social behavior was compared to vehicle-injected controls. Dihydrexidine induced higher levels of reactivity among isolated than among group-reared animals, especially in NC900 mice. In independent experiments, increased densities of D1 dopamine receptors in the striatum of isolated animals were found, with no change in affinity. These studies suggest an important role for the D1 dopamine receptor as a mediator of isolation-induced social reactivity.
Aggression↗
Cystic lymphangioma of the colon: ultrasonographic and computed tomographic features.
Cystic lymphangioma is a rare benign tumour of the gastrointestinal tract. The authors describe a 52-year-old woman with cystic lymphangioma in the ascending colon. Ultrasonographically, the lesion was compressible and anechoic and showed posterior acoustic enhancement. Doppler analysis showed no flow within the lesion. On computed tomography the lesion appeared as a focal thickening of the colonic wall with attenuation values of 6 to 10 Hounsfield units. The lesion extended along the wall and did not invade the adjacent fat. It could not be located during endoscopy or laparotomy and was eventually located for resection with intraoperative ultrasonography.
Colonic Neoplasms↗
Social reactivity and D1 dopamine receptors: studies in mice selectively bred for high and low levels of aggression.
Robust individual differences in social behavior have been obtained by selectively breeding Institute for Cancer Research mice for high and low levels of aggression. As previously shown, when paired with a non-selected group-housed partner mouse, NC900 mice exhibit isolation-induced aggression. Conversely, NC100 mice fail to attack, freezing upon social contact. Previous studies have established that NC100 mice have lower dopamine concentrations in nucleus accumbens and caudate nucleus, with increased dopamine receptor densities in these same regions. Thus, we wished to determine the effect of administration of a dopamine receptor agonist on social behavior. Mice of both lines were administered 0, 1, 3, or 10 mg/kg (SC) of the full efficacy D1 receptor agonist dihydrexidine, and their behavior was assessed in a social interaction test. Dihydrexidine reduced aggression in NC900 mice and nonagonistic approach in NC100 mice in a dose dependent manner. In both cases, this resulted from induction of a marked reactivity to mild social stimulation as measured by increases in behaviors such as escape, reflexive kicking, and vocalizations. Dihydrexidine had no systematic effect on the freezing behavior characteristic of the low-aggressive line. In independent experiments, mice were pretreated with either the D1 antagonist SCH-23390 (.1 mg/kg) or the selective D2 antagonist remoxipride (1.0 mg/kg), after which they received dihydrexidine (10 mg/kg) and were tested as above. The effects of dihydrexidine on social reactivity in mice of both lines were significantly antagonized by SCH-23390 but not attenuated by remoxipride.(ABSTRACT TRUNCATED AT 250 WORDS)
Aggression↗
Development, microevolution, and social behavior.
The central questions of social development--from the roots of mother-infant attachment to the plasticity of aggressive behavior--pivot on the relations between genetic and ontogenetic sources of variance. It is proposed that (a) developmental, experiential, and microevolutionary processes typically collaborate, rather than compete, in achieving social adaptation; (b) social behavior patterns are mostly closed to modification in the course of development and across generations, but avenues of vulnerability exist in ontogeny and microevolution for dynamic, rapid, and reversible changes in key features; (c) a general avenue for change is delay or acceleration in the developmental onset of one or more features of the behavior pattern, which in turn modifies the functions and properties of the adaptive configuration; and (d) the features of social behavior that are open to rapid change in ontogeny should be open as well to rapid changes in microevolution, although different underlying processes may be involved. Empirical findings from the investigation of aggressive interactions are used to illustrate this proposal on the dual genesis and coincident adaptation of social behaviors.
Animals↗
A developmental-genetic analysis of aggressive behavior in mice (Mus musculus): III. Behavioral mediation by heightened reactivity or immobility?
This research was designed to investigate development and behavioral mediation in lines of ICR mice that have been selectively bred for aggressive behavior. General behavioral reactivity and behavioral immobility have been implicated as potential mediators by prior analyses of preattack interactions. To evaluate the separate roles of these dispositions, the emergence of attacks in genetically selected lines was tracked for 11 years by three levels of analysis: over successive generations, over development, and over dyadic interactions. Convergent outcomes were observed in all three levels with respect to two findings: (a) Robust line differences were obtained in attack behaviors, and (b) strong associations were found between line differences in attacks and line differences in behavioral immobility. Conversely, all three levels of analysis indicated a weak and inconsistent association between line differences in attacks and measures of social and nonsocial reactivity.
Aggression↗