Pre-Botzinger complex

The Pre-Bötzinger Complex (preBötC) is a cluster of interneurons in the ventrolateral medulla of the brainstem, which is essential to the generation of respiratory rhythm in mammals.^[1] The exact mechanism of the rhythm generation and transmission to motor nuclei remains controversial and the topic of much present research.^{[2][3][4][5][6][7]}

Several synthetic compounds have been shown to act on neurons specific to the preBötC, most being selective agonists or antagonists to receptor subtypes on neurons in the vicinity. Since many of these neurons express GABA, glutamate, serotonin^[8] and adenosine receptors, chemicals custom tailored to bind at these sites are most effective at altering respiratory rhythm.

One such novel compound that acts on this area of the brain, called BIMU8, has been discovered. BIMU8, along with other selective serotonin 5HT₄ receptor agonists such as zacopride, are thought to stimulate the preBötC, causing an increase in the rate of respiration which can block the respiratory depression produced by high doses of opioid drugs.^[9][10] Several ampakine drugs, such as CX-546,^[11] CX-717 and CX-1739, also stimulate this area, and some of these are being developed for use alongside opioids in human medicine.^[12][13]

Adenosine modulates the preBötC output via activation of the A₁ and A_2A receptor subtypes.^[14][15] An adenosine A₁ receptor agonist called N6-Cyclopentyladenosine (NCPA) has been shown to depress preBötC rhythmogenesis independent of the neurotransmitters GABA and glycine in "in vitro" preparations from 0-7 day old mice.^[16] Another synthetic drug specific to the adenosine A_2A receptor subtype is CGS-21680 that has been shown to cause apneas in 14-21 day old rat pups in vivo. For this reason, it has been used as a model to study pathological conditions such as apnea of prematurity and SIDS in neonatal infants.

See also

• Control of respiration
• Ventral respiratory group
• SIDS

References