Parietal Block Using Bupivacaine in the Rat: An Anatomical, Behavioral and Histological Study.

Area of Science:

• Anesthesiology
• Pain Research
• Animal Models

Background:

• Regional anesthesia techniques are crucial for pain management and research.
• Animal models are essential for validating new anesthetic procedures and understanding their mechanisms.
• Paravertebral blocks offer targeted anesthesia but require precise delivery methods.

Purpose of the Study:

• To validate a multi-site paravertebral block technique in a rat model.
• To assess the efficacy of this block in reducing mechanical nociception.
• To investigate the impact of the block on spinal cord neuronal activation.

Main Methods:

• A multi-site paravertebral injection technique was developed in rats.
• Bupivacaine or saline was administered laterally to the spinal column at multiple thoracic and lumbar levels.
• Mechanical nociception was evaluated using von Frey hairs, and c-Fos expression in the spinal cord was quantified.

Main Results:

• The paravertebral injection demonstrated a localized distribution without systemic spread.
• Bilateral paravertebral block with bupivacaine significantly increased the pain threshold (p=0.007).
• Bupivacaine administration significantly reduced c-Fos immunoreactive nuclei in the spinal cord posterior horn (p<0.0001).

Conclusions:

• A multi-site paravertebral abdominal wall block is technically feasible in rats.
• This validated block model facilitates the investigation of abdominal wall block mechanisms.
• The findings support the use of this model for preclinical pain research.