Substantia gelatinosa opiate receptors

The opiate receptors in the spinal cord are predominantly of the mu and delta type and are found in the C-fibre terminal zone (the substantia gelatinosa) in the superficial dorsal horn. Considerable numbers of ORL-1 receptors are also found in this area. Up to 75% of the opiate receptors are found presynaptically on the C-fibre terminals and when activated inhibit neurotransmitter release. The opening of potassium channels will reduce calcium flux in the terminal and so there will be a resultant decrease in... 

Fig. 3. The autoradiographic localization of opiate receptors in the rat spinal cord. This is a bright-field micrograph showing regions of the dorsal horn. Note the high concentrations of autoradiographic grains (hence, opiate receptors) over the substantia gelatinosa (sg), while there is a much lower level over Lissauer s tract (LT) and an intermediate level over lamina IV. (Reproduced from Atweh and Kuhar 1977a.)...

Opiate receptors in the substantia gelatinosa of the spinal cord appear to be the main site of drug action after epidural drug administration. However, an... 

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