The locomotor effects of quinpirole in rats depend on age and gender
K J Frantz1, C Van Hartesveldt
1Department of Psychology, University of Florida, Gainesville 32611-2250, USA.
Insights
Periadolescent rats show adult-like responses to quinpirole, a dopamine agonist. Locomotor activity changes with age and sex, indicating developmental shifts in neurobehavior.
Area of Science:
- Neuroscience
- Developmental Psychology
- Pharmacology
Background:
- Periadolescence (postnatal day 35-50) is a critical neurodevelopmental stage in rats.
- This period is understudied regarding neurobehavioral responses to pharmacological agents.
- Previous research has explored quinpirole's effects in other age groups.
Purpose of the Study:
- To investigate the effects of quinpirole on locomotor activity in periadolescent rats.
- To characterize age- and sex-dependent responses to a dopamine D2/D3 receptor agonist during this developmental window.
Main Methods:
- Rats at postnatal day 40 or 50 were administered varying doses of quinpirole (0.0-2.0 mg/kg) subcutaneously.
- Locomotor activity was monitored following drug administration within a single test session.
- Data were analyzed to identify dose-, age-, and sex-specific behavioral patterns.
Main Results:
- Periadolescent rats exhibited adult-like biphasic locomotor responses (suppression followed by activation) to higher quinpirole doses (0.2 and 2.0 mg/kg).
- Lower quinpirole doses elicited only early locomotor suppression in younger females (PND40) and older males (PND50).
- Locomotor activation in males decreased with increasing age, suggesting a developmental decline.
Conclusions:
- Periadolescent rats display a continuum of locomotor responses to quinpirole, transitioning from weaning to adulthood.
- Neurobehavioral sensitivity to dopamine D2/D3 receptor agonists changes significantly during periadolescence.
- These findings highlight the dynamic nature of neurodevelopment and drug response in this critical period.
Abstract:
Periadolescence in the rat [postnatal day (PND) 35-50] is an important but understudied period of neurobehavioral development. In this experiment, an ongoing survey of the effects of quinpirole in developing rats was completed by the addition of periadolescent rats to the range of ages tested. PND40 or 50 rats were injected subcutaneously with the dopamine D2/D3 receptor agonist, quinpirole (0.0, 0.02, 0.2, or 2.0 mg/kg), and their locomotor activity was recorded. Periadolescent rats showed adult-like locomotor responses to either the 0.2 or 2.0 mg/kg doses of quinpirole, i.e., the responses were biphasic with respect to time: early suppression of locomotion followed by later activation within a single test session. In younger female rats (PND40) but older male rats (PND50), the lowest dose of quinpirole suppressed activity early in the test session but did not increase it later. In male rats, the magnitude of locomotor activation declined with age. Taken together with previous data from this laboratory, these results suggest that periadolescent rats exhibit locomotor responses that fall along a continuum from a high level of activation just after weaning to a low level of activation in early adulthood.
