Vanhatalo S, Soinila S
Department of Anatomy, University of Helsinki, Finland.
Brain Res. 1996 Nov 18;740(1-2):253-60. doi: 10.1016/s0006-8993(96)00873-6.
Neuropeptide Y (NPY)-containing neural projections to the rat pituitary gland were studied by combining NPY immunohistochemistry with retrograde tracing with Fluorogold as well as central and peripheral denervations. Numerous pituitary-projecting, i.e. Fluorogold-labelled, neurons in the superior cervical ganglion, as well as in the hypothalamic magnocellular nuclei were NPY-immunoreactive (NPY-IR). In contrast, no other hypothalamic NPY-IR neurons, e.g. in the arcuate nucleus or the preoptic area, were observed to be projecting into the pituitary. Within the posterior lobe of the pituitary gland two morphologically distinct NPY-IR fiber populations were discovered, namely thinner parenchymal terminals, distinct from the neurosecretory terminals, and thicker, perivascular fibers. Neurosecretory nerve terminals, in contrast, were devoid of NPY-IR, being consistent with the previous reports on their sensitivity to osmotic stimulation. On the other hand, the anterior and intermediate lobes contained no NPY-IR fibers. Bilateral extirpation of the superior cervical ganglion resulted in disappearance of the perivascular NPY-IR fibers leaving the parenchymal NPY-IR fibers unaffected, while transection of the pituitary stalk abolished all of the parenchymal NPY-IR neurons, leaving the perivascular fibers unaffected. These findings together with the observed colocalization of tyrosine hydroxylase and NPY in the posterior lobe perivascular fibers indicated that they are sympathetic nerve endings. The thin parenchymal terminals, instead, are suggested to stem from central sources other than hypothalamus. Our findings indicate that the pituitary gland receives NPY-containing innervation from at least three distinct sources, and NPY may thus affect pituitary functions in various ways, such as blood flow and vasopressin release.
通过将神经肽Y（NPY）免疫组织化学与荧光金逆行追踪以及中枢和外周去神经支配相结合，研究了向大鼠垂体投射的含NPY神经纤维。颈上神经节以及下丘脑大细胞神经核中许多投射到垂体的神经元，即荧光金标记的神经元，是NPY免疫反应性的（NPY-IR）。相比之下，未观察到其他下丘脑NPY-IR神经元，如弓状核或视前区的神经元投射到垂体。在垂体后叶内发现了两种形态不同的NPY-IR纤维群，即较细的实质终末，与神经分泌终末不同，以及较粗的血管周围纤维。相比之下，神经分泌神经终末缺乏NPY-IR，这与之前关于它们对渗透压刺激敏感性的报道一致。另一方面，垂体前叶和中叶不含NPY-IR纤维。双侧切除颈上神经节导致血管周围NPY-IR纤维消失，而实质NPY-IR纤维未受影响，而切断垂体柄则消除了所有实质NPY-IR神经元，血管周围纤维未受影响。这些发现以及在后叶血管周围纤维中观察到的酪氨酸羟化酶和NPY的共定位表明它们是交感神经末梢。相反，细的实质终末被认为起源于下丘脑以外的中枢来源。我们的发现表明，垂体至少从三个不同来源接受含NPY的神经支配，因此NPY可能以多种方式影响垂体功能，如血流和血管加压素释放。
