Immunohistochemical localization of serotonin in the brain stem of Rana pipiens (amphibia)

The indirect antibody peroxidase-anti-peroxidase technique was used to immunocytochemically localize serotonin (5HT) neurons in the frog brain stem. The 5HT neurons were found as expected in the nucleus isthmi, and also the different nuclei. They were located in the region extending from posterior of the cranial nerve VIII level (caudally) to anterior of nucleus interpeduncularis level (rostrally), both close to the midline and also in the lateral area. The midline raphe reticular nuclei with 5HT neurons were the raphe obscurus, raphe pallidus, raphe magnus, raphe pontis, raphe dorsalis, raphe centralis superior and raphe linearis. The laterally-located reticular nuclei with 5HT neurons were the reticularis magnocellularis, reticularis gigantocellularis, reticularis paragigantocellularis, reticularis pontis oralis pars medialis and pars lateralis, reticularis pedunculopontis, reticularis cuneiformis and reticularis sub-cuneiformis. Previously it has been suggested that the 5HT neurons of non-mammalian veterbrates are confined to only the midline raphe nuclei. However, a lateralization of the 5HT system from the midline raphe region was found in Rana pipiens. The frog reticular groups with 5HT neurons were similar to those found in the mammalian reticular system. Thus, the organization of 5HT system in the frog suggests that the organization is phylogenetically old

Immunohistochemistry and spinal projections of the reticular formation in the northern leopard frog, Rana pipiens

Over 30 nuclei have been identified in the reticular formation of rats, but only a small number of distinct reticular nuclei have been recognized in frogs. We used immunohistochemistry, retrograde tracing, and cell morphology to identify nuclei within the brainstem of Rana pipiens. FluoroGold was injected into the spinal cord, and, in the same frogs, antibodies to enkephalin, substance P, somatostatin, and serotonin were localized in adjacent sections. We identified many previously unrecognized reticular nuclei. The rhombencephalic reticular formation contained reticularis (r.) dorsalis; r. ventralis, pars alpha and pars beta; r. magnocellularis; r. parvocellularis; r. gigantocellularis; r. paragigantocellularis lateralis and dorsalis; r. pontis caudalis, pars alpha and pars beta; nucleus visceralis secundarius; r. pontis oralis, pars medialis and pars lateralis; raphe obscurus; raphe pallidus; raphe magnus; and raphe pontis. The mesencephalic reticular formation contained locus coeruleus-subcoeruleus, r. cuneiformis, r. subcuneiformis, raphe dorsalis-raphe centralis superior, and raphe linearis. Thus, the reticular formation of frog, which is an anamniote, is organized complexly and is similar to the reticular formation in amniotes. Because many of these nuclei may be homologous to reticular nuclei in mammals, we used mammalian terminology for frog reticular nuclei. (C) 1999 Wiley-Liss, Inc

Immunohistochemical localization of substance-P, somatostatin, enkephalin, and serotonin in the spinal-cord of the northern leopard frog, Rana-pipiens

Using the indirect antibody peroxidase-antiperoxidase method of Sternberger, we localized substance P (SP), somatostatin (SOM), enkephalin (ENK), and serotonin (5HT, 5-hydroxytryptamine) in the spinal cord of Rana pipiens. This is the first study to demonstrate all four substances in adjacent sections of frog spinal cord. The distribution patterns of ENK, SP, SOM, and 5HT in our study differ from that described for laminae I and II in amniotes. A high density of ENK, SP, and SOM fibers is present in a band ventral to the dorsal terminal field of cutaneous primary afferent fibers and slightly overlapping the ventral terminal field of muscle primary afferent fibers. However, a high density of 5HT fibers is present in the dorsal terminal field