Related Experiment Videos
Enkephalin-induced myoclonic twitches blocked by ergometrine and potentiated by haloperidol
Abstract:
Myoclonic twitches (MT) in the submandibular muscles induced by intraventricular administration of D-ala2-met-enkephalinamide (DALA) were studied electromyographically in the rat. Measurement of MT activity was selected since it permits parallel study of the effect of enkephalin on both dopaminergic and serotonergic transmitter systems. The twitches induced by enkephalin were blocked by naloxone, gamma-hydroxybutyrate, and ergometrine, but potentiated by haloperidol. Methysergide did not alter the stimulatory effect of DALA. These results were interpreted as a possibility for a specific enkephalin-induced activation of the so-called inhibition-mediating dopaminergic system, which is sensitive to the blocking action of ergometrine, but resistant to the blocking action of haloperidol.
Insights
Enkephalin-induced myoclonic twitches in rats suggest activation of a specific dopaminergic system. This system is sensitive to ergometrine but not haloperidol, offering new insights into neurotransmitter interactions.
Area of Science:
- Neuropharmacology
- Neurophysiology
Background:
- Opioid peptides, like enkephalins, play crucial roles in modulating neuronal activity.
- Understanding the specific receptor systems involved in enkephalin's effects is essential for neuroscience research.
Purpose of the Study:
- To investigate the neurochemical mechanisms underlying enkephalin-induced myoclonic twitches (MT) in rat submandibular muscles.
- To explore the involvement of dopaminergic and serotonergic systems in these enkephalin-mediated effects.
Main Methods:
- Electromyographic (EMG) recordings were used to measure MT in rats.
- Pharmacological agents including naloxone, gamma-hydroxybutyrate, ergometrine, haloperidol, and methysergide were administered to assess their effects on DALA-induced MT.
Main Results:
- Intraventricular administration of D-ala2-met-enkephalinamide (DALA) induced significant MT.
- These twitches were blocked by naloxone, gamma-hydroxybutyrate, and ergometrine.
- Haloperidol potentiated the MT, while methysergide had no significant effect.
Conclusions:
- The findings suggest a specific enkephalin-induced activation of an inhibition-mediating dopaminergic system.
- This dopaminergic system appears to be sensitive to ergometrine blockade but resistant to haloperidol blockade.