Histochemistry And Immunohistochemistry Studies Of Nuclei Associated With Visceral And Cardiovascular Regulation In Rat Brain And The Ultrastructural Observations Of Their Mutual Projections

Objcetive: To provide the anatomic data for further understanding of the role of nitric oxide (NO) in the central visceral and cardiovascular regulation and the mechanism of hypothalamus-hypophysis neurohumoral regulation mediated by NO , We studied the distribution of nitric oxide synthase (NOS) positive neurons and the coexistence of NOS and oxytocin(OT)or f3-endorphin(j3-EOP), and projections in some nuclei of hypothalamus and brainstem which are involved in central visceral and cardiovascular regulation. All those results will give the basis material for exploration and perfection of the new neuroendocrine network , in which nitric oxide-gaseous neuromediator plays an important role. Materials and methods : The distribution of NOS positive neurons in the nuclei of hypothalamus and brainstem was observed by NADPH-diaphorase histochemitry method. Cytoarchitecture and projections of NOS neurons in the paraventricular nucleus(PVN), the parabrachi al nucleus(PBN) ,the locus coeruleus nucleus (LC), the SoLitary nucleus (SoL) were investigated by combining with the horseradish peroxidase(HRP) retrograde tracing techniques, The coexistence of NOS with OT or -EOP was studied in the third ventricle or brainstem by combining NADPH-diaphorase histochemical technique with immunocytochemical methods in the same section . By combining the anterograde degeneration method caused by electrolytic lesions with HRP retrograde tracing techniques, We also observed the SoL-PBN-CAN indirect connection pathway in the rat on the electron microscopic level Results: 1. NOS positive neurons in the hypothalamus could be divided into two types: microcellular NOS positive neurons and magnocellular NOS positive neurons. The former were almost in the region of microcellular neurosecretory neurons, the latter were in the region of magnocellular 8 neurons, especially in the PVN and supraoptic nucleus . A large number of NOS positive fibres were aggregate at the external and medial lamina of the median eminence (ME) respectively connecting with the anterior or posterior lobe of the pituitary 2.In the PVN, the microcellular NOS positive neurons were in the minority , scattering over the parvocellular division and dorsomedial cap . The majority of magnocellular NOS positive neurons were aggregate at four magnocellular subneclei of PVN : anterior commissural nucleus(AC) , medial paraventricular nucleus , lateral paraventricular nucleus , and posterior subnucleus of the paraventricular nucleus (PvPO).Their NOS fibres projected to the posterior lobe of the pituitary gland. In the PVM and PVL,some NOS positive neurons projected to neighbors region of the limb system including the central nucleus of the amygdala (CAN) , while in the parvocellular division,the dorsomedial cap and PvPO , some NOS positive neurons were found projecting to the brainstem nuclei, such as parabrachial nucleus.3. NOS positive cerebrospinal fluid-contacting neurons(NOS-CSFCN) cound be found in all the four walls of the third ventricle. In each wall, the morphology and distribution of NOS-CSFCN and the ratio of coexistence of NOS/OT were different . The range of the distri...