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Effects of early handling upon puberty: correlations with adrenal stress responsiveness
Insights
Weekly handling of rat pups delays puberty, including vaginal opening and ovulation. This handling also reduces stress response, highlighting the need for consistent procedures in developmental studies.
Area of Science:
- Reproductive biology
- Developmental toxicology
- Animal behavior
Background:
- Standard laboratory procedures, such as animal handling, can inadvertently influence experimental outcomes.
- Developmental processes in rodents are sensitive to environmental factors.
Purpose of the Study:
- To investigate the impact of routine handling on the pubertal development and stress response of rat pups.
- To determine if combined handling and bedding changes exacerbate these effects.
Main Methods:
- Rat pups were handled for 5 minutes weekly before weaning.
- Handling involved weighing the litter.
- Some groups also had bedding replaced.
- Stress response was assessed via ether stress at 60 days of age.
Main Results:
- Weekly handling significantly delayed vaginal opening and ovulation.
- Handling also reduced the response to ether stress.
- Combined handling and bedding replacement led to further delays in puberty and reduced stress response.
Conclusions:
- Routine handling procedures can significantly alter reproductive development and stress reactivity in rats.
- Uniform handling protocols are essential for studies investigating developmental processes to ensure data validity.
- Environmental factors, including bedding changes, can compound the effects of handling.
Abstract:
Handling of rat pups for 5 min once a week prior to weaning to permit weighing of the litter significantly delays vaginal opening and ovulation and is associated with a reduction in the response to an ether stress administered at 60 days of age. Handling combined with replacement of the bedding material results in a further delay in puberty and a further reduction in the stress response. It is therefore necessary to follow uniform handling procedures in any study of a developmental process.