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Published on: December 14, 2014
Neonatal fluoxetine exposure alters motor performances of adolescent rats
Li-Jen Lee1, Lukas Jyuhn-Hsiarn Lee
1Graduate Institute of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan. ljlee@ntu.edu.tw
Insights
Early exposure to fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI) antidepressant, impairs motor function and alters neural structure in developing rats. These effects on the motor system highlight concerns regarding long-term impacts of neonatal SSRI exposure.
Area of Science:
- Neuroscience
- Developmental Biology
- Pharmacology
Background:
- Maternal antidepressant use during pregnancy is linked to adverse neonatal outcomes.
- Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed antidepressants.
- The long-term effects of early-life SSRI exposure on motor system development require further investigation.
Purpose of the Study:
- To investigate the impact of neonatal fluoxetine (FLX) exposure on motor function and neural structure in adolescent rats.
- To determine if early SSRI exposure leads to lasting motor deficits.
- To identify specific neuroanatomical changes associated with early FLX treatment.
Main Methods:
- Neonatal rat pups were treated with FLX or saline from birth to postnatal day 4.
- Motor performance was assessed during adolescence using open field and accelerating rotarod tests.
- Neuronal structure, including dendritic spine density and dendritic complexity, was examined in motor-related brain regions (striatum and primary motor cortex).
Main Results:
- FLX-treated rats exhibited reduced locomotor activity and poorer rotarod performance compared to controls.
- Motor deficits showed significant improvement with repetitive practice.
- Reduced dendritic spine density was observed in striatal and M1 Layer 5 neurons.
- M1 Layer 5 neurons displayed reduced dendritic complexity in FLX-exposed rats.
Conclusions:
- Neonatal exposure to FLX affects both the function and structure of the developing motor system.
- Impaired dendritic structures in the striatum and motor cortex may underlie motor performance deficits.
- Long-term consequences of early SSRI exposure on motor system development warrant significant concern.
Abstract:
Growing evidence from human and animal studies has shown adverse consequences of maternal usage of antidepressants in their newborn babies. To study the effects of early antidepressant exposure on motor function later in life, we treated neonatal rat pups with fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI)-type antidepressant, from the day of birth to postnatal day 4 and examined motor performance during adolescence. FLX-treated rats had reduced locomotor activities in an open field and poorer motor performance on an accelerating rotarod compared to the control group of saline-treated animals. Nevertheless, the poorer motor performance largely improved after repetitive practices. To elucidate the structural alterations in the motor system, we examined the structure of neurons in motor-related brain regions. The shape, density, and soma size of cerebellar Purkinje cells were comparable in the two groups, however, density of dendritic spine in medial spiny neurons of striatum and Layer 5 pyramidal neurons in the primary motor cortex (M1) were reduced in FLX-rats. Furthermore, the basilar dendrites in M1 Layer 5 neurons had reduced dendritic complexity than those of the control animals. The impaired dendritic structure in striatal and cortical neurons in FLX-treated rats might account for their poorer motor performances. Together, the structure and function of the motor system are affected by early FLX exposure, the long-term effects of early exposure to SSRI-type antidepressants should be concerned.
