Phenotypes associated with this allele

• Allele Symbol: Drd4^tm1Dkg
• Allele Name: targeted mutation 1, David K Grandy
• Allele ID: MGI:2178631
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Drd4^tm1Dkg/Drd4^tm1Dkg	involves: 129P2/OlaHsd	MGI:5431887
hm2	Drd4^tm1Dkg/Drd4^tm1Dkg	involves: 129P2/OlaHsd * C57BL/6J	MGI:3614358

Genotype
MGI:5431887

hm1

• Allelic Composition: Drd4^tm1Dkg/Drd4^tm1Dkg
• Genetic Background: involves: 129P2/OlaHsd

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

vision/eye

abnormal eye electrophysiology ( J:185955 )

• overall light-adapted electroretinographic response is significantly reduced

• on day 2 in constant darkness, circadian regulation of the light-adapted electroretinographic response is abolished

abnormal vision ( J:185955 )

• optokinetic tracking indicates a decrease in contrast sensitivity over multiple spatial frequencies

Genotype
MGI:3614358

hm2

• Allelic Composition: Drd4^tm1Dkg/Drd4^tm1Dkg
• Genetic Background: involves: 129P2/OlaHsd * C57BL/6J

behavior/neurological

behavior/neurological phenotype ( J:55027 )

N • amphetamine-treated mice exhibit normal reductions in prepulse inhibition and startle reactivity

hyperactivity elicited by ethanol administration ( J:43061 )

• homozygotes are supersensitive to the locomotor-stimulating effects of ethanol (20% v/v) relative wild-type mice

enhanced behavioral response to cocaine ( J:43061 )

• homozygotes display a dose-dependent hypersensitivity to the locomotor-stimulating effects of cocaine and methamphetamine

impaired behavioral response to addictive substance ( J:43061 )

• unlike wild-type, catecholamine-depleted, akinetic-rendered homozygotes fail to exhibit a 40% suppression of apomorphine-induced locomotor activity in response to 0.6 mg/kg clozapine

• however, both genotypes of mice exhibit complete loss of apomorphine-induced locomotion in response to 6 mg/kg clozapine

decreased exploration in new environment ( J:76023 )

• in the open field test, homozygotes make fewer entries into the center, but do not differ in overall levels of activity relative to wild-type mice

• in the emergence test, homozygotes spend more time in the cylinder and make fewer entries into the cylinder relative to wild-type mice

• in the novel object test, homozygotes exhibit a smaller increase in % of time spent in the center after introduction of the cup relative to wild-type mice

• overall, homozygotes display the largest reductions in behavioral responses to novelty in the test that maximizes approach behaviors (novel object test), and the smallest reductions in the test that maximizes avoidance behavior (open field test)

enhanced coordination ( J:43061 )

• homozygotes outperform their wild-type littermates on the rotarod, with 50% fewer falls and a 2.5-fold increase in the length of time remaining on the rotarod

decreased vertical activity ( J:43061 )

• homozygotes exhibit fewer rearing episodes in an open field environment relative to wild-type mice

decreased locomotor activity ( J:43061 )

• homozygotes cover less horizontal distance, initiate fewer movements and spend less time in motion in an open field environment relative to wild-type mice

• female homozygotes appear to be slightly more active than males

nervous system

nervous system phenotype ( J:55027 )

N • amphetamine-treated mice exhibit normal reductions in prepulse inhibition and startle reactivity

homeostasis/metabolism

increased dopamine level ( J:43061 )

• following DOPA decarboxylase inhibition, homozygotes accumulate more L-DOPA in the dorsal striatum-caudate putamen (CPU) relative to wild-type mice

• homozygotes exhibit elevated dopamine synthesis and its conversion to DOPAC in the dorsal striatum, as shown by a 93% increase of DOPAC content in CPU and a 1.9-fold increase in DOPAC/DA ratio relative to wild-type mice