Ethologically Based Resolution of D₂-Like Dopamine Receptor Agonist-versus Antagonist-Induced Behavioral Topography in Dopamine- and Adenosine 3′,5′-Monophosphate-Regulated Phosphoprotein of 32 kDa “Knockout” Mutants Congenic on the C57BL/6 Genetic Background

Abstract

Given the critical role of dopamine-and adenosine 3Ј,5Ј-monophosphate-regulated phosphoprotein of 32 kDa in the regulation of dopaminergic function, DARPP-32-null mutant mice congenic on the inbred C57BL/6 strain for 10 generations were examined phenotypically for their ethogram of responsivity to the selective D 2 -like receptor agonist RU 24213 (N-npropyl-N-phenylethyl-p-3-hydroxyphenylethylamine) and the selective D 2 -like receptor antagonist YM 09151-2 (cis-N-[1-benzyl-2-methyl-pyrrolidin-3-yl]-5-chloro-2-methoxy-4-methylaminobenzamide), using procedures that resolve all topographies of behavior in the natural repertoire. After vehicle challenge, levels of sniffing and rearing seated were reduced in DARPP-32 mutants; the injection procedure seems to constitute a "stressor" that reveals phenotypic effects of DARPP-32 deletion not apparent under natural conditions. Topographical effects of 0.3 to 10.0 mg/kg RU 24213, primarily induction of sniffing and ponderous locomotion with accompanying reductions in rearing, grooming, sifting and chewing, were not altered to any material extent in DARPP-32-null mice. However, topographical effects of 0.005 to 0.625 mg/kg YM 09151-2, namely, reduction in sniffing, locomotion, rearing, grooming, and chewing but not sifting, were essentially absent in DARPP-32 mutants. Thus, the D 2 -like receptor agonist-mediated ethogram was essentially conserved, whereas major elements of the corresponding D 2 -like receptor antagonist-mediated ethogram were essentially absent in DARPP-32-null mice. This suggests some relationship between 1) extent of tonic dopaminergic activation of DARPP-32 mechanisms and 2) compensatory mechanisms consequent to the developmental absence of DARPP-32, which may emerge to act differentially on individual elements of the DARPP-32 system. Critically, the present data indicate that phenotypic effects of a given gene deletion using an agonist acting on the system disrupted cannot be generalized to a corresponding antagonist, and vice versa. subtypes in the regulation of mammalian behavior remains uncertain because of delay in the identification of a full range of selective agonists and antagonists by medicinal chemistry relative to the rate of identification of these receptor subtypes by molecular biology (Waddington et al., 1995;Di Chiara, 2002;Sidhu et al., 2003). The construction of mutants with targeted gene deletion ("knockout") of each individual dopamine receptor subtype has provided an important approach to addressing this issue (Sibley, 1999;Waddington et al., 2001). However, elucidation of the

Exploratory and habituation phenotype of heterozygous and homozygous COMT knockout mice

“…Behavioural assessments were carried out using a rapid time-sampling behavioural checklist technique, as described previously in detail [20,21,23,28]. In outline, 10 mice (Fig.…”

Dopamine D1 vs D5 receptor-dependent induction of seizures in relation to DARPP-32, ERK1/2 and GluR1-AMPA signalling

“…As described previously (Nally et al, 2004;O'Sullivan et al, 2004O'Sullivan et al, , 2006O'Tuathaigh et al, 2006), for specification of the agonist-induced ethogram, the total 'counts' for each individual behavior were determined as the number of 5 s observation windows in which a given behavior was evident, summed over the 3 × 15 min [0 -15, 20 -35, 40 -55] cycle periods; data were expressed as means ± SEM. Stereotypy scores were averaged over the 60 min period and expressed similarly.…”

“…To establish congenic lines, heterozygous knockouts of these hybrid D 1 , D 5 and DARPP-32 strains were backcrossed to wild-type C57BL/6 for 15, 10 and 11 generations, respectively (McNamara et al, 2003;Nally et al, 2004;O'Sullivan et al, 2005). Analysis of isolated genomic DNA by PCR was used to genotype the progeny of heterozygous D 1 , heterozygous D 5 and homozygous DARPP-32 intermatings.…”

“…Mice were then allowed to habituate for a period of 3 h to reduce initially high levels of activity in order to optimise detection of agonist-induced stimulatory effects. Immediately following challenge with SKF 83822 (0.016 -2.0 mg/kg s.c.) or vehicle, assessments were carried out using a rapid time-sampling behavioral checklist technique and stereotypy rating scale, as previously described (Nally et al, 2004;c, 2006;O'Tuathaigh et al, 2006). For this study, the following components of the ethogram are reported: sniffing (flaring of nostrils with movement of vibrissae); locomotion (coordinated movement of all four limbs producing a change in location); rearing to wall (front paws reaching upwards onto or towards a cage wall while standing on hind limbs); total grooming (grooming of any form); intense grooming (characteristic, programmed syntax of sequential grooming of the snout and then the face with the forepaws, followed by grooming of the hind flank/anogenital region with the snout); seizures, characterised as any of the following phases occurring within the 60 min observation period: phase 1 = sustained immobility/rigidity; phase 2 = rearing with forepaw myoclonus; phase 3 = generalized clonus; phase 4 = tonic-clonic seizure or rapid jumping and wild running (Ferraro et al, 1999;McKhann et al, 2003;O'Sullivan et al, 2006); stillness (motionless: awake with no behavior evident, or asleep).…”

Disruption of orofacial movement topographies in congenic mutants with dopamine D5 but not D4 receptor or DARPP-32 transduction ‘knockout’

“…and analysed using repeated-measures analysis of variance (ANOVA) after square-root transformation in the absence of appropriate non-parametric techniques; univariate comparisons were made where overall effects on ANOVA were significant, using Student's t-test or Mann-Whitney U-test after Kruskal-Wallis analysis as appropriate Ross et al, 2000;Tomiyama et al, 2001Tomiyama et al, , 2002Tomiyama et al, , 2004Makihara et al, 2004;Nally et al, 2003Nally et al, , 2004O'Sullivan et al, 2004O'Sullivan et al, , 2005. Fienberg et al, 1998;Nally et al, 2003Nally et al, , 2004.…”