β-Neurexins Control Neural Circuits by Regulating Synaptic Endocannabinoid Signaling

Area of Science:

• Neuroscience
• Molecular Biology
• Synaptic Plasticity

Background:

• α- and β-neurexins are presynaptic cell-adhesion molecules linked to autism and schizophrenia.
• β-neurexins are expressed at lower levels than α-neurexins.

Purpose of the Study:

• Investigate the role of β-neurexins in neurotransmitter release and synaptic function.
• Determine the involvement of β-neurexins in endocannabinoid signaling and neural circuit regulation.

Main Methods:

• Conditional knockout of β-neurexins in cultured cortical neurons and in vivo.
• Pharmacological inhibition of CB1-receptor and 2-arachidonoylglycerol synthesis.
• Electrophysiological recordings to assess synaptic transmission and long-term potentiation (LTP).
• Behavioral tests to evaluate contextual fear memories.

Main Results:

• Conditional knockout of β-neurexins significantly decreased neurotransmitter release at excitatory synapses.
• The knockout phenotype was modulated by inhibiting CB1-receptor or 2-arachidonoylglycerol synthesis.
• Presynaptic β-neurexin knockout aggravated endocannabinoid-mediated inhibition and blocked LTP, effects reversed by pharmacological interventions.
• Knockout of β-neurexins in CA1 neurons impaired contextual fear memories.

Conclusions:

• Presynaptic β-neurexins regulate synaptic strength in excitatory synapses by controlling postsynaptic 2-arachidonoylglycerol synthesis.
• β-neurexins play an unexpected role in the endocannabinoid-dependent regulation of neural circuits.
• These findings shed light on the molecular mechanisms underlying synaptic plasticity and memory formation.