The interrelation between the latero-dorsal tegmental area and lumbosacral segments of rats as studied by HRP method

Satoh et al. (1978a) demonstrated that Barrington's nucleus in the rat corresponds to the nucleus laterodorsalis tegmenti (TLD), immediately ventromedial to the rostral pole of the locus coeruleus (LC). To confirm this finding and to identify the course of the tracts and their terminals, we injected small amounts of HRP into the TLD, LC and the lumbar and sacral segments followed by the DAB and TMB reaction. Injection of HRP into the TLD resulted in the anterograde staining of descending fibers in the latero-ventral part of the lateral funiculus, which mainly terminate in the intermediate area of the sacral segments, and in the retrograde labeling of a large number of cells in the intermediate area of the sacral segments. After injection of HRP into the sacral segments, marked labeling of many TLD cells was demonstrated in contrast to that of only a small number of LC cells. On the other hand, after injection of HRP into the LC, a moderate number of descending fibers were found in the ventral part of the lateral funiculus, with small numbers in the apex of the dorsal horn and ventral funiculus, mainly ending in the intermediate gray of the lumbar segments. Moreover, moderate numbers of retrogradely labeled cells were revealed in the intermediate area of the lumbar segments. From these results it may be concluded that the reciprocal interrelation between the TLD and intermediate gray of the sacral segments is more important for the micturition reflex than that between the LC and lumbo-sacral segment.