Summary A total of 152 ventrolateral medullary neurons was antidromically stimulated from both the medial preoptic/anterior hypothalamic area (MPOAH) and the medial forebrain bundle (MFB) in urethane anesthetized rats. These neurons were located primarily dorsal to the lateral reticular nucleus and could be readily classified in at least two groups, type I and type II cells on the basis of electrophysiological properties. The action potentials of type I cells had a shorter duration, and their conduction velocities ranged from 0.45 to 3.1 m/s. By contrast, type II cells, most predominantly observed, were characterized by a longer duration and an unusual shape of their action potential, and the antidromic propagation into the somatodendritic complex was often blocked. The conduction velocity (mean = 0.21 m/s) and absolute refractory period (mean = 2.63 ms) of type II cells are consistent with them having fine non-myelinated axons. Injection of 6-hydroxydopamine (6-OHDA), but not 5,7-dihydroxytryptamine, directly into the MFB blocked antidromic responses of 57% of type II cells tested. The residual type II cells whose antidromic responses were not affected by 6-OHDA were located significantly rostral to the 6-OHDA sensitive cells. Neither antidromic response of type I cells tested, on the other hand, was affected by 6-OHDA. The majority of type I cells were dramatically activated by noxious pinches of the tail, whereas the noxious stimuli produced no detectable change in the firing of type II cells. These data demonstrate that ventrolateral medullary neurons projecting to the MPOAH through the MFB are comprised of at least three distinct populations: 6-OHDA resistant fast conducting cells with somatic afferents, 6-OHDA sensitive and resistant slow conducting cells. 相似文献
The development of retinal projections to the pretectal complex of prenatal and early postnatal cats has been examined using the anterograde transport of horseradish peroxidase and tritiated amino acids. As early as embryonic day 38, the entire dorsal pretectum is penetrated by retinal ganglion cell axons. At this stage the bilateral complement of retinal efferents appears to be dispersed uniformly within the pretectal anlage. A week later, on embryonic day 46, indistinct foci of peroxidase reaction product can be discerned within 2 of the primordial nuclei: the nucleus of the optic tract and the olivary nucleus. By embryonic day 56, five distinct bilateral fields of retinal fiber termination are apparent within the following regions:
(i) the nucleus of the optic tract;
(ii) the pretectal olivary nucleus;
(iii) the posterior pretectal nucleus;
(iv) the anterior pretectal nucleus; and
(v) the medial pretectal nucleus. Four days before birth, on embryonic day 61, crossed and uncrossed retinal arbors are partially segregated within the nucleus of the optic tract and the pretectal olivary nucleus.
The early postnatal retinal connection to the pretectum has an overall pattern virtually indistinguishable from that of the mature cat. The ontogeny of the retinal influx to the pretectum is similar to that of the retinocollicular projection.61 However, the development of retinal projections to the pretectum and superior colliculus appears to lag behind those to the dorsal lateral geniculate nucleus.49 These differences may reflect temporal and spatial gradients in the maturation of three major classes of retinal ganglion cells. 相似文献
A 22-year-old woman with Cushing's syndrome, caused by an extremely rare suprasellar ectopic pituitary adenoma, is presented. Magnetic resonance imaging and computed tomography revealed a well-circumscribed mass in the right suprasellar region. Endocrinological tests showed elevated s-adrenocorticotropic hormone level and hypercortisolemia. The tumor was totally removed by right subfrontal approach. At the time of the operation, the tumor was in continuity with the distal pituitary stalk but not with the pituitary gland. The diaphragma sellae was intact. Histologic diagnosis of the tumor specimen was confirmed as a pituitary adenoma. After surgical removal of the tumor, continued improvement in the patient's laboratory results and disappearance of her endocrine symptoms strongly indicated the absence of adenoma cells in the pituitary gland or stalk. Six years post-surgery, there was no evidence of recurrence in the patient's clinical and laboratory examination. This tumor probably originated from aberrant anterior pituitary cells of the pituitary stalk. 相似文献
To investigate the spontaneous turning off mechanism of endogenous uveitis, EAAU was induced in Lewis rats. Immunohistochemical and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) stains revealed that CD4+ T cells were predominant in the uveal tissue of EAAU and that the apoptosis of these cells had occurred and progressed throughout the inflammatory period in EAAU eyes. The immunohistochemistry and in situ hybridization for Fas ligand (FasL) expression showed that the expression of Fas ligand was increased in the EAAU eyes compared with control eyes. These results suggest that the apoptosis of CD4+ T cells may play a key role in the spontaneous turning off mechanism of intra-ocular inflammation and that the induction of apoptosis may be mediated by the Fas-FasL system in EAAU. 相似文献
Regardless of the side of hemiovariectomy, unilateral lesion placed in the right-side medial anterior hypothalamus suppressed ovarian compensatory hypertrophy, but the lesion made in the left side failed to suppress it. This suggests the presence of a hypothalamic laterality in regulating gonadotropin secretion. 相似文献
HLA antigens are associated with a number of inflammatory eye diseases, most notably HLA B2 with anterior uveitis (AU). This association varies between different populations and ethnic groups. The aim of this study was to investigate the relationship between uveitis and HLA A, B and DR locus antigens in an Australian population. Seventy-two consecutive patients with uveitis were studied (37 males and 35 females) over a 6 month period. Thirty-two percent of the AU patients were HLA B27+, as were 42% of males (19% females) with their first attack of AU compared with 60% of males (23% females) with recurrent AU. The only significant difference in etiology between males and females was the greatly increased incidence of rheumatic diseases in males, in whom 77% (10/13) had radiological evidence of sacroiliitis. Additional findings included a lack of association between the HLA B7 cross reactive group and DR locus antigens in AU as well as the lack of any HLA associations in the 13 patients with posterior uveitis (PU). 相似文献