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Strain-difference in circadian murine chronotolerance to the antidepressant drug nomifensine
Abstract:
The anti-depressant drug nomifensine (8-amino-1,2,3,4-tetrahydro-methyl-4-phenylisoquinoline) was administered at several dose levels to mice of 2 inbred strains at one of 6 circadian times 4h apart under conditions standardized for light-dark synchronized rhythmometry. A circadian rhythm in tolerance to nomifensine reflected by differences in mortality was demonstrated for both C57 and DBA mice. An interstrain difference in tolerance was also observed.
Insights
Mice show varying tolerance to the antidepressant nomifensine based on their internal body clock and genetic strain. This circadian rhythm in drug response highlights the importance of timing in pharmacotherapy.
Area of Science:
- Pharmacology
- Chronobiology
- Neuroscience
Background:
- The antidepressant nomifensine (8-amino-1,2,3,4-tetrahydro-methyl-4-phenylisoquinoline) has been studied for its effects.
- Understanding drug efficacy and toxicity often requires considering biological rhythms and genetic factors.
Purpose of the Study:
- To investigate the influence of circadian timing on nomifensine tolerance in mice.
- To examine potential differences in nomifensine tolerance between two inbred mouse strains (C57 and DBA).
Main Methods:
- Nomifensine was administered to C57 and DBA mice at six different circadian times, spaced 4 hours apart.
- Mortality rates were used to assess tolerance to varying doses of nomifensine.
- Experiments were conducted under standardized light-dark cycle conditions.
Main Results:
- A significant circadian rhythm in nomifensine tolerance was observed in both C57 and DBA mouse strains.
- Differences in mortality indicated that tolerance to nomifensine varied depending on the time of administration.
- An interstrain difference in tolerance to nomifensine was also detected between the C57 and DBA mice.
Conclusions:
- Circadian rhythms significantly impact the tolerance of nomifensine in mice.
- Genetic background (inbred strain) also plays a role in nomifensine tolerance.
- These findings underscore the importance of chronopharmacology in antidepressant drug administration.