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[Sex-dependent differences in parameters of a long-term pain caused by inflammatory focus in prenatally stressed
Insights
Prenatal stress in rat pups alters pain response dynamics. Stressed males show heightened pain sensitivity in the second phase compared to females, indicating early-life stress impacts pain pathways.
Area of Science:
- Neuroscience
- Developmental Biology
- Pain Research
Context:
- Prenatal stress is a known factor influencing neurodevelopment.
- The formalin test is a standard model for evaluating nociceptive responses.
- Early-life pain perception mechanisms are not fully understood.
Purpose:
- To investigate the effect of prenatal immobilization stress on the nociceptive behavioral response in 7-day-old Long-Evans rat pups.
- To analyze the temporal dynamics and sexual dimorphism of pain responses following inflammatory stimuli.
Summary:
- Prenatal stress exposure in rat pups resulted in a two-phase nociceptive response in the formalin test, unlike the single-phase response in controls.
- The second, tonic phase of the pain response was significantly more pronounced in prenatally stressed males than females.
- This suggests prenatal stress sensitizes pain pathways, with males exhibiting greater sensitivity in the tonic phase.
Impact:
- Prenatal stress can mature pain response mechanisms prematurely in developing rats.
- The findings highlight sex-specific differences in pain processing following early-life stress.
- This research contributes to understanding the long-term consequences of prenatal adversity on pain perception.
Abstract:
In experiments on the 7-day-old female and male Long-Evans rat pups, for the first time, there was studied effect of prenatal (immobilization) stress on dynamics of nociceptive behavioral response caused by an inflammatory focus. The nociceptive sensitivity was evaluated for 1 h by the number of 7-day-old organized at the spinal level in response to injection of formalin (10%, 10 microl) to the posterior leg sole. Control rat pups were not submitted to any prenatal stress; in these animals the response in the formalin test was found to be represented by one phase. It the prenatally stressed rat pups the studied patterns were organized into two phases characteristic of the definitive type of response. At the period between them (during interphase), the nociceptive behavior was absent. At the second, tonic phase the number of flexes+shakes in the prenatally stressed males was statistically significantly higher than in the prenatally stressed females, which indicates a sensitization of the neurons involved in the tonic pain chains in male individuals. Thus, the data obtained on prenatally stressed animals confirm the previous data about immaturity of the mechanisms mediating the second phase of response in the formalin test in the 7-day-old rat pups. An important fact is revealed which indicates that in the prenatally stressed rat pups of the same age the second phase of response is already obvious. Mechanisms underlying the behavioral response caused by the inflammatory focus in the formalin test in the number flexes + shakes old stressed rat pups are characterized by sexual dimorphism: the pain sensitivity in males at the second phase of response is statistically significantly higher than in females.
