Vasopressin modulates lateral septal network activity via two distinct electrophysiological mechanisms

• Published in: The European journal of neuroscience 2007-11, Vol.26 (9), p.2633-2642
• Main Authors: Allaman-Exertier, G., Reymond-Marron, I., Tribollet, E., Raggenbass, M.
• Format: Article
• Language: English
• Subjects: action potential discharge; Animals; Antidiuretic Hormone Receptor Antagonists; Binding, Competitive - drug effects; Binding, Competitive - physiology; cell-attached recording; gamma-Aminobutyric Acid - metabolism; inhibitory postsynaptic current; Inhibitory Postsynaptic Potentials - drug effects; Inhibitory Postsynaptic Potentials - physiology; light microscopic autoradiography; Nerve Net - drug effects; Nerve Net - metabolism; Neural Inhibition - drug effects; Neural Inhibition - physiology; Neural Pathways - drug effects; Neural Pathways - metabolism; Neurons - drug effects; Neurons - metabolism; Organ Culture Techniques; Patch-Clamp Techniques; Radioligand Assay; rat; Rats; Rats, Sprague-Dawley; Receptors, Vasopressin - agonists; Receptors, Vasopressin - drug effects; Receptors, Vasopressin - metabolism; Septal Nuclei - drug effects; Septal Nuclei - metabolism; Social Behavior; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Vasopressins - pharmacology; Vasopressins - physiology; whole-cell recording
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/j.1460-9568.2007.05866.x

The lateral septal area is rich in vasopressin V1A receptors and is densely innervated by vasopressinergic axons, originating mainly from the bed nucleus of the stria terminalis and the amygdala. Genetic and behavioral studies provide evidence that activation of vasopressin receptors in this area plays a determinant role in promoting social recognition. What could be the neuronal mechanism underlying this effect? Using rat brain slices and whole‐cell recordings, we found that lateral septal neurons are under the influence of a basal GABAergic inhibitory input. Vasopressin, acting via V1A but not V1B receptors, greatly enhanced this input in nearly all neurons. The peptide had no effect on miniature inhibitory postsynaptic currents, indicating that it acted on receptors located in the somatodendritic membrane, rather than on axon terminals, of GABAergic interneurons. Cell‐attached recordings showed that vasopressin can cause a direct excitation of a subpopulation of lateral septal neurons by acting via V1A but not V1B receptors. The presence in the lateral septum of V1A but not of V1B receptors was confirmed by competition binding studies using light microscopic autoradiography. In conclusion, vasopressin appears to act in the lateral septum in a dual mode: (i) by causing a direct excitation of a subpopulation of neurons, and (ii) by causing an indirect inhibition of virtually all lateral septal neurons. This modulation by vasopressin of the lateral septal circuitry may be part of the neuronal mechanism by which the peptide, acting via V1A receptors, promotes social recognition.