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Receptors

Some neurons in the SFO are osmoreceptors, being sensitive to the osmotic pressure of the blood. These neurons project to the supraoptic nucleus and paraventricular nucleus to regulate the activity of vasopressin-secreting neurons. These neurons also project to the nucleus medianus (also called the median preoptic nucleus) which is involved in controlling thirst. Thus, The subfornical organ is involved in fluid balance.

In addition, neurons in the SFO have receptors for many hormones that circulate in the blood but which do not cross the blood–brain barrier, including angiotensin, atrial natriuretic peptide, endothelin and relaxin.

Relevant Experiments

Feeding

Although generally viewed primarily as having roles in homeostasis and cardiovascular regulation, the subfornical organ has been thought to control feeding patterns through taking inputs from the bloodstream (various peptides indicating satiety) and then stimulating hunger. It has been shown to induce drinking in rats, but this is the first study that looked at eating. This study also looks at different stimulation current values, to determine if this has an effect on the amount of feeding that occurs.

The rats studied were separated into three groups: rats with electrodes in their subfornical organ with no current passing through (sham), rats with stimulated subfornical organs, and rats with areas other than the subfornical organ stimulated. The group with stimulated subfornical organs was separated into groups with 100mA and 200mA stimulations. All rats were satiated (food and drink) before observations/stimulations were done, and were also monitored for general activity. The group with subfornical stimulation at 100mA drank an increased amount, but did not consume any additional food, and the group with 200mA consumed both more water and more food. All groups without subfornical organ stimulation did not eat or drink at all .