Chapter 9 - Receptors in the Human Spinal Cord

Abstract

This chapter focuses on receptors in human spinal cord. The distribution of benzodiazepine/GABA A receptors in the human spinal cord demonstrates that these receptors are distributed in a consistently similar fashion in the gray matter of the cervical, thoracic, lumbar, and sacral regions of the human spinal cord. Receptor proteins are also detected in regions that are associated with nonsynaptic sites in the dorsal horn. The primary nociceptive afferents release substance P, and opiates inhibit the release of substance P both in vitro and in vivo , which suggests that opiates modulate nociceptive transmission by acting directly on primary afferent terminals. The mechanism of action of neurotensin in modulating sensory activities in the dorsal horn is complex, and there is interaction of neurotensin with other neurotransmitters because the superficial laminae of the dorsal horn are enriched with a wide variety of neurotransmitters and their receptors. Adenosine has a nanomolar affinity for A1 receptor and micromolar affinity for A2 receptor. NMDA receptors are implicated in the transmission of nociception.