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Potentiating effects of methamphetamine on the hyperactivity of microencephalic rats treated prenatally with

M Watanabe1, K Shimizu, Y Kodama

  • 1Department of Psychiatry, National Defense Medical College, Saitama, Japan.

Brain Research
|January 23, 1995
PubMed

Insights

Methylazoxymethanol (MAM) induced microencephalic rats exhibit hyperactivity. Methamphetamine

Area of Science:

  • Neuroscience
  • Developmental Neuroscience
  • Behavioral Neuroscience

Background:

  • Methylazoxymethanol (MAM) exposure in utero can lead to microcephaly in offspring.
  • Microcephalic individuals often exhibit behavioral abnormalities, including hyperactivity.
  • The neurobiological underpinnings of MAM-induced hyperactivity are not fully understood.

Purpose of the Study:

  • To investigate the motor activity and response to stimulant drugs in rats with MAM-induced microcephaly.
  • To explore the role of dopaminergic systems in the hyperactivity observed in MAM rats.

Main Methods:

  • Rats were exposed to MAM during gestation to induce microcephaly.
  • Behavioral parameters including locomotion and rearing were assessed using an automated field apparatus.
  • The effects of acute and chronic methamphetamine (MAP) administration on motor activity were evaluated.
  • Dopamine receptor densities (D1 and D2) were measured in control and MAM rats.

Main Results:

  • MAM-induced microencephalic rats displayed significantly higher levels of hyperactivity compared to control rats.
  • Acute methamphetamine administration potentiated motor activity in both control and MAM rats, with a more pronounced effect in MAM rats.
  • Chronic methamphetamine treatment did not alter D1 or D2 dopamine receptor densities in either group.

Conclusions:

  • Augmented dopaminergic function is suggested to contribute to the hyperactivity observed in MAM-induced microencephalic rats.
  • The results indicate a potential hypersensitivity to stimulant drugs in MAM rats, possibly mediated by non-receptor related dopaminergic mechanisms.

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