[1][2][3] There are three main classes of imidazoline receptor: I1 is involved in inhibition of the sympathetic nervous system to lower blood pressure,[4] I2 has as yet uncertain functions but is implicated in several psychiatric conditions,[5][6] and I3 regulates insulin secretion.
[8][9] In addition, activation inhibits the sodium-hydrogen antiporter and enzymes of catecholamine synthesis are induced, suggesting that the I1 receptor may belong to the neurocytokine receptor family, since its signaling pathways are similar to those of interleukins.
[8] Animal research suggests that much of the antihypertensive action of imidazoline drugs such as clonidine is mediated by the I1 receptor.
[12][13] Preliminary research in rodents suggests that I2 receptor agonists may be effective in chronic, but not acute pain, including fibromyalgia.
[12] I2 receptor activation has also been shown to decrease body temperature, potentially mediating neuroprotective effects seen in rats.