Comparison of hyperactivity in adult rats induced by neonatal intraventricular 6-hydroxydopamine following pargyline or desmethylimipramine treatment
✍ Scribed by M. E. Olds; Arthur Yuwiler
- Publisher
- Springer
- Year
- 1985
- Tongue
- English
- Weight
- 658 KB
- Volume
- 87
- Category
- Article
- ISSN
- 0033-3158
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✦ Synopsis
The relative roles of norepinephrine (NE) and dopamine (DA) in sustaining neonatal hyperactivity were assessed in rats given 6-hydroxydopamine (6-OHDA) neonatally into the lateral ventricles after pargyline (P) or desmethylimipramine (DMI) pretreatment.
On day 5 after birth, male and female rat pups were pretreated with P (50 mg/kg IP) or DMI (25 mg/kg IP) 30 rain before receiving bilateral injections of 6-OHDA (200 gg/5 gl saline containing ascorbic acid 1.0 mg/ml) into the lateral ventricles. Controls were pretreated with P or DMI and then received injections of saline containing the aseorbate.
Spontaneous activity was measured in a stabilimeter at ages 30-31, 42-45, 60-63, 75-77, and 120-122 days. Activity in controls and P + 6-OHDA animals was also measured at 254 days of age. The sessions lasted 45 min, except those testing activity in the 254-day-old rats which lasted 12h.
Regional assays of catecholamines carried out when the animals were 150 days old revealed that in the P + 6-OHDA group the levels of NE were reduced in frontal cortex (7% of control levels), caudate (21%), and hippocampus (14%). The NE levels were unchanged or slightly elevated in hypothalamus, ventral midbrain, and pons. The DA levels in the P + 6-OHDA group were depleted in caudate (8%) and ventral midbrain (32%), and unchanged in hypothalamus and pons.
In the DMI + 6-OHDA group the NE levels were reduced in caudate (25%) and elevated in hippocampus (188%). The DA levels were depleted in caudate (3%) and ventral midbrain (22%).
Both treatments resulted in long-term hyperactivity, but the syndrome was of larger magnitude and more permanent in the P + 6-OHDA group. The possible biochemical basis of these differential effects is discussed.