Reduced P2X receptor levels are associated with antidepressant effect in the learned helplessness model

Area of Science:

• Neuroscience
• Pharmacology
• Psychiatry

Background:

• Purinergic receptors, particularly P2RX family members, are implicated in the severity of depressive and bipolar disorders.
• Genetic or pharmacological inhibition of P2RX7 demonstrates antidepressant-like effects in preclinical studies.
• Limited research exists on P2RX7/P2RX4 alterations and behavioral outcomes following stress exposure, a key depression risk factor.

Purpose of the Study:

• To investigate the impact of imipramine (IMI) on P2RX7 and P2RX4 levels in rat brain regions after learned helplessness (LH) paradigm exposure.
• To assess the behavioral effects of P2RX7/P2RX4 antagonist Brilliant Blue G (BBG) in the LH paradigm.

Main Methods:

• Rats underwent the learned helplessness (LH) paradigm pretest session.
• Repeated or acute administration of imipramine (IMI) or Brilliant Blue G (BBG) was performed.
• Levels of P2RX7 and P2RX4 were measured in the dorsal hippocampus, ventral hippocampus, and frontal cortex.
• The efficacy of BBG and IMI was evaluated by measuring failures to escape in the LH test session.

Main Results:

• Repeated, but not acute, IMI administration decreased P2RX7 and P2RX4 levels in the ventral hippocampus.
• Neither IMI nor BBG affected receptor levels in the dorsal hippocampus or frontal cortex.
• Repeated treatment with BBG (50 mg) significantly reduced failures to escape in the LH test.
• This antidepressant-like effect of BBG mimicked the outcome of repeated IMI treatment.

Conclusions:

• Repeated IMI administration is associated with reduced P2RX7 and P2RX4 expression in the ventral hippocampus.
• Pharmacological blockade or reduced expression of P2RX7 correlates with antidepressant-like behavior in the LH paradigm.
• These findings highlight the role of P2RX7 in stress-induced behavioral deficits and suggest potential therapeutic targets for depression.