Abstract
Rats were given continuous subcutaneous amphetamine infusions (0, 2, 6, 10 and 20 mg/kg/day) via osmotic minipumps. The effects of these treatments on the locomotor activity of rats were determined over both light and dark phases of a 12-hr light/dark cycle for 336 consecutive hours. It was observed that tolerance to the locomotor stimulant actions of (+)-amphetamine is both dose- and light/dark cycle-dependent. Locomotor stimulation induced by the two highest doses remained high during both day and night throughout the period of treatment, except for the first few days and nights with the highest dose. Tolerance developed only to the effects of the two lower doses, and only during the day. Effects of the low doses on locomotor activity and on circadian patterns of locomotor activity are rughly similar to those previously observed with continuous administration of a selective dopamine D2 agonist. This behavioral similarity suggests that dopamine released by continuous administration of low doses of (+)-amphetamine may be producing its effects via selective actions on DA D2 receptors in vivo.
| Original language | English |
|---|---|
| Pages (from-to) | 465-471 |
| Number of pages | 7 |
| Journal | Pharmacology, Biochemistry and Behavior |
| Volume | 34 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 1 Jan 1989 |
| Externally published | Yes |
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Day and night locomotor activity effects during administration of (+)-amphetamine. / Martin-Iverson, M. T.; Iversen, S. D.
In: Pharmacology, Biochemistry and Behavior, Vol. 34, No. 3, 01.01.1989, p. 465-471.Research output: Contribution to journal › Article
TY - JOUR
T1 - Day and night locomotor activity effects during administration of (+)-amphetamine
AU - Martin-Iverson, M. T.
AU - Iversen, S. D.
PY - 1989/1/1
Y1 - 1989/1/1
N2 - Rats were given continuous subcutaneous amphetamine infusions (0, 2, 6, 10 and 20 mg/kg/day) via osmotic minipumps. The effects of these treatments on the locomotor activity of rats were determined over both light and dark phases of a 12-hr light/dark cycle for 336 consecutive hours. It was observed that tolerance to the locomotor stimulant actions of (+)-amphetamine is both dose- and light/dark cycle-dependent. Locomotor stimulation induced by the two highest doses remained high during both day and night throughout the period of treatment, except for the first few days and nights with the highest dose. Tolerance developed only to the effects of the two lower doses, and only during the day. Effects of the low doses on locomotor activity and on circadian patterns of locomotor activity are rughly similar to those previously observed with continuous administration of a selective dopamine D2 agonist. This behavioral similarity suggests that dopamine released by continuous administration of low doses of (+)-amphetamine may be producing its effects via selective actions on DA D2 receptors in vivo.
AB - Rats were given continuous subcutaneous amphetamine infusions (0, 2, 6, 10 and 20 mg/kg/day) via osmotic minipumps. The effects of these treatments on the locomotor activity of rats were determined over both light and dark phases of a 12-hr light/dark cycle for 336 consecutive hours. It was observed that tolerance to the locomotor stimulant actions of (+)-amphetamine is both dose- and light/dark cycle-dependent. Locomotor stimulation induced by the two highest doses remained high during both day and night throughout the period of treatment, except for the first few days and nights with the highest dose. Tolerance developed only to the effects of the two lower doses, and only during the day. Effects of the low doses on locomotor activity and on circadian patterns of locomotor activity are rughly similar to those previously observed with continuous administration of a selective dopamine D2 agonist. This behavioral similarity suggests that dopamine released by continuous administration of low doses of (+)-amphetamine may be producing its effects via selective actions on DA D2 receptors in vivo.
KW - (+)-Amphetamine
KW - Circadian rhythms
KW - Dopamine D1/D2 receptors
KW - Locomotor activity
KW - Rat
KW - Sensitization
KW - Tolerance
UR - http://www.scopus.com/inward/record.url?scp=0024845242&partnerID=8YFLogxK
U2 - 10.1016/0091-3057(89)90542-X
DO - 10.1016/0091-3057(89)90542-X
M3 - Article
VL - 34
SP - 465
EP - 471
JO - Pharmacology Biochemistry and Behavior
JF - Pharmacology Biochemistry and Behavior
SN - 0091-3057
IS - 3
ER -