Distribution of Neuropeptide mRNA-Containing Neurons and Changes of Their Gene Expression in the Rat Periaqueductal Gray in a Neuropathic Pain Model / 대한해부학회지

The distribution of enkephalin, dynorphin, substance P and neurotensin in the periaqueductal gray[PAG] has been well established by immunohistochemical methods. However, there is little information about the regional distribution of these neuropeptide mRNA-containing neurons in the PAG. The present study was undertaken [1] to elucidate the distribution of these neuropeptide mRNA-containing neurons and to determine of the PAG, [2] to know how peptide expression relates to the proposed functional subdivisions of the PAG and [3] to know how neuropeptide mRNA levels in the PAG change following peripheral neuropathy The results obtained are as follows ; 1. Preproenkephalin[pENK] mRNA-containing neurons are found mostly in the ventrolateral portion at all levels of the PAG. 2. Prodynorphin[pDYN] mRNA-containing neurons are concentrated mostly in the ventrolateral portion at the caudal level of the PAG. 3. Preprotachykinin[pTAK] mRNA-containing neurons are localized mainly in the ventrolateral portion at all levels of the PAG. There is small numbers of pTAK mRNA-containing neurons in the dorsolateral and dorsal portion at all levels of the PAG. 4. Proneurotensin[pNT] mRNA-containing neurons are concentrated mostly in the medial part of ventrolateral portion of the caudal and mid PAG. 5. Peripheral neuropathy induces an increase of pNT mRNA levels in the PAG, while pENK, pDYN and pTAK mRNAs levels show no change. The present results indicate that the pENK, pDYN, pTAK or pNT mRNA-containing neurons are found mainly in the ventrolateral PAG, the area where analgesia is most easily produced and that neurotensin in the PAG may play an important role in modulating chronic neuropathic pain.

Distribution of Tyrosine Hydroxylse Immunoreactive Structure in the Spinal Cord and Dorsal Root Ganglion of the Rat / 대한해부학회지

With the aim of gaining more insight into the catecholaminergic system in the nervous system of the rat, we have studied the precise distribution pattern of the tyrosine hydroxylase immunoreactive[TH-IR] fibers and soma in the spinal cord and dorsal root ganglion. In the dorsal root ganglion[DRG], TH-IR fibers were observed to run along the vessel wall, spirally and not found in the neural tissue itself. A few TH-IR fibers were found in the spinal nerve, not in the ventral root. Many TH-IR neurons were distributed in the L3, 4, 5, and 6 DRG but none of them were found in the other DRG segments. In the spinal cord, TH-IR fibers have shown sparse distribution all over spinal cord but relatively dense distribution in the ventral horn, intermediolateral column, lamina I of the dorsal horn of the cervical, lumbar, sacral, and coccygeal segment. TH-IR neurons were found in the intermediolateral column, dorsal gray commissure, dorsal horn of the C1 and C2 segments and S1-4 segments. TH-IR neurons in the cervical segments were polygonal and spindle shaped with well developed processes. In contrast to this, TH-IR neurons in the sacral segments were oval or spindle shaped with no processes. In conclusion, neurons in the DRG were not influenced by catecholaminergic nervous input. Intrinsic catecholaminergic nervous systems were found in both of spinal cord and DRG.