The supraoptic nucleus as an osmoreceptor.

The "Progress' review is written to challenge the prevalent belief that neurones of the supraoptic nucleus are not involved in the reception of osmotic stimuli. Evidence is presented that these neurones are depolarised by physiological increases in the osmotic pressure of the extracellular fluid. However, generation of action potentials in these depolarised cells still requires the presence of synaptic input from currently unidentified neurones. We suggest that the osmoreceptor regulating vasopressin secretion is probably composed of more than one type of neurone and discuss this suggestion in the context of selected experiments previously cited as evidence that the supraoptic nucleus is not involved in osmoreception.