Behavioral effects and anatomic correlates after brain injury: a progesterone dose-response study

Area of Science:

• Neuroscience
• Neuropharmacology
• Rehabilitation Science

Background:

• Progesterone shows promise for functional recovery after brain injury.
• High-dose, chronic pre-injury progesterone can worsen outcomes in stroke models.
• The dose-response effects of progesterone post-injury require further investigation.

Purpose of the Study:

• To investigate the dose-dependent effects of progesterone on behavioral recovery after cortical contusion.
• To examine the relationship between progesterone dosage and GABA-A receptor expression post-injury.
• To determine the optimal dose range for progesterone treatment following brain injury.

Main Methods:

• Male rats with cortical contusions received varying doses of progesterone (0, 8, 16, 32 mg/kg) post-injury.
• Behavioral assessments included the Morris water maze (MWM) and somatosensory neglect testing.
• Thalamic GABA-A receptor density was analyzed in relation to behavioral performance.

Main Results:

• Low (8 mg/kg) and moderate (16 mg/kg) doses of progesterone reduced thigmotaxis in the MWM compared to control and high-dose groups.
• High-dose (32 mg/kg) progesterone showed increased variability in some behavioral tests, indicating potential disruption.
• Progesterone treatment did not significantly alter lesion size.
• A negative correlation was found between thalamic GABA-A receptor density and MWM performance.

Conclusions:

• Low to moderate post-injury doses of progesterone are optimal for facilitating behavioral recovery after cortical contusion.
• Post-injury progesterone administration allows for a wider effective dose range compared to pre-injury treatment.
• The observed correlation suggests a role for GABA-A receptor density in mediating progesterone's effects on cognitive function post-brain injury.