Neurophysiological characterization of mammalian osmosensitive neurones.

In mammals, the osmolality of the extracellular fluid is maintained near a predetermined set-point through a negative feedback regulation of thirst, diuresis, salt appetite and natriuresis. This homeostatic control is believed to be mediated by osmosensory neurones which synaptically regulate the electrical activity of command neurones that mediate each of these osmoregulatory effector responses. Our present understanding of the molecular, cellular and network basis that underlies the central control of osmoregulation is largely derived from studies on primary osmosensory neurones in the organum vasculosum lamina terminalis (OVLT) and effector neurones in the supraoptic nucleus (SON), which release hormones that regulate diuresis and natriuresis.

Visually guided whole cell patch clamp of mouse supraoptic nucleus neurons in cultured and acute conditions.

Recent advances in neuronal culturing techniques have supplied a new set of tools for studying neural tissue, providing effective means to study molecular aspects of regulatory elements in the supraoptic nucleus of the hypothalamus (SON). To combine molecular biology techniques with electrophysiological recording, we modified an organotypic culture protocol to permit transfection and whole cell patch-clamp recordings from SON cells. Neonatal mouse brain coronal sections containing the SON were dissected out, placed on a filter insert in culture medium, and incubated for at least 4 days to allow attachment to the insert.