Guglielmotti V, Fiorino L
Institute of Cybernetics, CNR, Arco Felice, Naples, Italy.
J Comp Neurol. 1999 Aug 30;411(3):441-54. doi: 10.1002/(sici)1096-9861(19990830)411:3<441::aid-cne7>3.0.co;2-n.
In the adult frog, structural asymmetry of the left dorsal habenula in respect to the right counterpart has been repeatedly documented in previous studies. In the present investigation, histochemical expression of beta-nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity was examined in the habenulae of the developing and adult Rana esculenta. In tadpoles and during metamorphosis, selective neuropil staining was consistently found within a lateral compartment of the medial subnucleus of the left dorsal habenula. The staining was still present in the same location, but much less intense, in the mature frog, indicating that the neurochemical pattern observed during development was at least in part transient. Thus, the present data point out a peculiar neurochemical pattern of the habenular asymmetry in the frog, suggesting that nitric oxide may be involved in the developmental shaping which leads to an asymmetrical configuration of the habenulae. In addition, NADPH-diaphorase-positive cells were detected in the frontal organ (the extracranial component of the pineal complex in strict relationship with the habenulae in the frog), and labeled fibers were found in the frontal nerve, which arises from the frontal organ. This latter finding supports the postulated relationship of the habenular asymmetry with the occurrence of the frontal organ. The finding of NADPH-diaphorase histochemical reactivity confined to a distinct portion of the medial subnucleus of the left dorsal habenula prompted a reexamination of the cytoarchitecture of the developing and mature habenular complex in the frog. The bicompartmentalization detected with histochemistry in the medial subnucleus of the left dorsal habenula of the developing and adult frog was fully supported by the study of Nissl-stained epithalamic sections. These data point out that the left-right structural differences of the frog habenular complex are more complex than previously believed, and may be subserved by chemically regulated developmental processes.
在成年青蛙中，先前的研究已多次记录了左背侧缰核相对于右侧对应结构的结构不对称性。在本研究中，检测了发育中和成年食用蛙缰核中β-烟酰胺腺嘌呤二核苷酸磷酸（NADPH）-黄递酶活性的组织化学表达。在蝌蚪和变态发育期间，始终在左背侧缰核内侧亚核的外侧隔室内发现选择性神经纤维染色。在成熟青蛙中，染色仍出现在同一位置，但强度要小得多，这表明在发育过程中观察到的神经化学模式至少部分是短暂的。因此，目前的数据指出了青蛙缰核不对称性的一种特殊神经化学模式，表明一氧化氮可能参与了导致缰核不对称构型的发育塑造过程。此外，在额器（松果体复合体的颅外部分，与青蛙的缰核有密切关系）中检测到NADPH-黄递酶阳性细胞，并且在源自额器的额神经中发现了标记纤维。后一发现支持了缰核不对称性与额器出现之间的假定关系。局限于左背侧缰核内侧亚核特定部分的NADPH-黄递酶组织化学反应性的发现，促使对青蛙发育中和成熟的缰核复合体的细胞结构进行重新检查。对尼氏染色的上丘脑切片的研究完全支持了在发育中和成年青蛙左背侧缰核内侧亚核中通过组织化学检测到的双室化。这些数据指出，青蛙缰核复合体的左右结构差异比以前认为的更为复杂，并且可能由化学调节的发育过程所支持。
