NGF-producing transfected 3T3 cells: behavioral and histological assessment of transplants in nigral lesioned rats.

The rodent fibroblast clonal cell line, 3T3, was retrovirally transfected with the rat nerve growth factor (NGF) gene and selected for NGF synthesis. This study tested the hypothesis that transplanted 3T3 cells, transfected to secrete nerve growth factor (3T3NGF+), change motor behavioral indices created by striatal denervation in a dose-dependent fashion. 3T3NGF+ cells were transplanted into the lateral ventricle of rats following ipsilateral lesions of the substantia nigra pars compacta by stereotaxic injections of 6-hydroxydopamine (10 micrograms), an established lesion model. Control groups included vehicle injections and transplanted untransfected cells. The extent of the lesions was measured by determining rotational behavior before and two weeks after transplantation. Immediately prior to transplantation, cells were incubated with the fluorescent dye marker, Dil. To assess cell viability, whole brains were cryosectioned and examined for Dil-labeled 3T3 cells using fluorescent microscopy. The number of Dil-labeled profiles in five animals per group were counted in at least five noncontiguous sections per animal. From these data a statistically derived estimate of viable, transplanted 3T3 cells was obtained. The number of surviving transplanted cells correlated with the behavioral changes measured. The 3T3NGF+ transplants reduced rotational behavior, while control 3T3 transplants exacerbated rotational behavior. Thus, while NGF delivery was found to be beneficial, it was apparent that naive 3T3 had detrimental effects. These results underscore the importance of making dose-response measurements when attempting transplant-based modifications of CNS behavior.

Central inhibition of nitric oxide synthase attenuates water intake but does not alter enhanced glucose utilization in the hypothalamo-neurohypophysial system of dehydrated rats.

I.c.v. administration of a nitric oxide (NO) synthase inhibitor (NG-monomethyl-L-arginine, NMMA, 500 micrograms/5 microliters) to conscious rats deprived of water for 24 h attenuated drinking and decreased glucose utilization in the subfornical organ and median preoptic nucleus. NMMA did not alter the enhanced glucose utilization in the hypothalamo-neurohypophysial system (HNS) of dehydrated rats, although it has been shown to increase, selectively, oxytocin (OT) secretion [18]. This suggests that NO may act in the neural lobe to inhibit OT secretion and promote the preferential release of vasopressin during dehydration. This effect is similar to the blockade of endogenous opiate receptors by naloxone.

Disconnection as a cause of ventriculoperitoneal shunt malfunction in multicomponent shunt systems.

The cause of malfunction in 275 consecutive ventriculoperitoneal (VP) shunt revisions over an 8-year period were retrospectively analyzed. In all cases the shunt revised was a multicomponent (Holter) VP shunt. Disconnections in the system accounted for 41 (15%) of the malfunctions. The more distal the connection was from the ventricle, the higher the likelihood of disconnection. Furthermore, occipitally placed shunts had a significantly higher tendency to dislocate than frontally placed shunts.

Calcitonin gene-related peptide (CGRP) in the human spinal cord: a light and electron microscopic analysis.

The distribution of CGRP immunoreactivity in the cervical, thoracic, lumbar, and sacral levels of the human spinal cord was mapped at the light microscopic level with the aid of a rabbit-generated antiserum against human calcitonin gene-related peptide (CGRP). CGRP-positive fibers formed a dense plexus in lamina I, II, the reticulated region of lamina V, and the tract of Lissauer at all spinal cord levels. The distribution of fibers showed some variations dependent on the cord level analyzed. At the light microscopic level, intervaricose fiber diameters consistently measured 1.0 micron or less, and two types of CGRP varicosities were observed: a small (1 to 2 microns in diameter), relatively round profile and a larger, (3 to 4 microns in diameter) oval or oblong profile. At the electron microscopic level, immunostained varicosities contained a mixture of round clear vesicles and vesicles that contained dense cores. The CGRP immunoreaction product was often associated with vesicles containing dense cores. The reaction product was also seen associated with clear round vesicles or in the cytoplasmic matrix. Postsynaptic elements included dendritic spines, small and large diameter dendritic shafts and vesicle containing profiles. The presence of CGRP in the superficial dorsal horn of human spinal cord is highly suggestive of a role in primary afferent transmission as postulated in lower vertebrates. This study establishes the distribution of CGRP at four different spinal levels in human cord and will serve as a basis for future studies related to the pathologic conditions affecting sensory systems.

Collaterals of spinothalamic tract cells to the periaqueductal gray: a fluorescent double-labeling study in the rat.

Spinothalamic tract (STT) cells were investigated in the rat to determine the distribution of STT cells with terminals in both the ventrobasal (VB) thalamus and the lateral periaqueductal gray (PAG). Two retrogradely transported fluorescent dyes (Diamidino yellow and Granular blue) were injected into each animal. The distribution of single- and double-labeled cells was mapped in the cervical, thoracic, lumbar and sacral spinal cord. An average of 1.4% of all STT cells and 6.2% of PAG cells projected to both VB thalamus and PAG. Double-labeled cells were observed only in cervical and lumbar levels of the spinal cord, with the greatest number found in the cervical enlargement. The double-labeled cells were located in laminae I and V and also in the lateral spinal nucleus (LSN). The number of double-labeled cells found in each of these 3 areas varied depending on the spinal cord level. This population of neurons exhibiting collaterals provide an anatomical mechanism by which noxious stimuli activate neurons not only in the thalamus but also in the PAG, which is an area involved in stimulation-produced analgesia (SPA).