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Penicillin activates spontaneous motility in chick embryos
Insights
Penicillin G activates chick embryo motility after 15 days of incubation, showing both spinal and supraspinal components. This motor reaction is a developmental process influenced by central inhibitory mechanisms.
Area of Science:
- Neuroscience
- Developmental Biology
- Pharmacology
Background:
- Penicillin G is known to affect motor activity.
- Understanding the developmental aspects of drug reactions in embryos is crucial.
Purpose of the Study:
- To investigate the developmental timeline of motor reactions to Penicillin G in chick embryos.
- To differentiate the spinal and supraspinal contributions to this reaction.
- To explore modulatory effects of neurotransmitters on the penicillin-induced motor response.
Main Methods:
- Intravenous injection of Penicillin G (0.9 x 10^6 IU/kg) into chick embryos (normal and spinal) from day 11 to 19 of incubation.
- Observation and quantification of embryonal motility.
- Administration of glycine and GABA to assess modulatory effects.
Main Results:
- Penicillin G induced motor activation starting from day 15 of incubation.
- A paroxysmal reaction with motor rest emerged in later stages (days 17-19).
- The reaction comprised approximately 40% spinal and 60% supraspinal components; glycine and GABA modulated the response.
Conclusions:
- Penicillin G's motor activation is dependent on the developmental stage of the central nervous system (CNS).
- The motor reaction is a developmental phenomenon involving both spinal and supraspinal pathways.
- Central inhibitory mechanisms play a role in the observed motor response to penicillin.
Abstract:
The development of the motor reaction to i.v. injection of the sodium salt of penicillin G in a dose of 0.9 x 10(6) I.U./kg egg weight was studied in chick embryos (normal and spinal) from the 11th to the 19th day of incubation. Penicillin first caused standard activation of embryonal motility from the 15th day of incubation, in both normal and spinal embryos. Activation was at first continuous in character (a twofold increase in the frequency of spontaneous movements). In 17- and particularly in 19-day embryos a typical paroxysmal reaction developed, with pronounced intervals of motor rest. The proportion of the spinal component in the penicillin reaction was abut 40% and of the supraspinal component about 60% of total motor activity. In older embryos (after the 15th day of incubation), the motor reaction to penicillin could be effectively modified by the systemic administration of glycine and GABA. It is concluded from the results that penicillin does not activate embryonal motor activity until a given stage of development of the CNS has been attained. It is a developmental phenomenon with a spinal and a supraspinal component, in which central inhibitory mechanisms participate.