Somatostatin modulates LTP in hippocampal CA1 pyramidal neurons: Differential activation conditions in apical and basal dendrites

• We studied the role of somatostatin in the modulation of LTP in CA1 hippocampus.
• Somatostatin system enhanced late-LTP in apical dendrites.
• Somatostatin system was not activated during early-LTP in apical dendrites.
• Somatostatin system was not activated with strong tetanization in basal dendrites.
• Somatostatin system was activated with theta burst stimulation in basal dendrites.

The cyclic neuropeptide, somatostatin, is widely expressed in mammalian brain and modulates hormone secretion and neurotransmission. The long-term potentiation (LTP) at Schaffer collateral synapses onto hippocampal CA1 pyramidal neurons has been intensively studied as a cellular model of learning and memory. The apical (stratum radiatum) and basal dendrites (stratum oriens) of CA1 pyramidal neurons differ in LTP induction and maintenance. Here the role of somatostatin in the modulation of LTP was investigated in rat hippocampus. Our results show that somatostatin enhances LTP in apical and basal dendrites. However, the activation conditions of the somatostatin system are different in these two compartments.