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W Foote

Publications and source records attributed to W Foote.

9 recordsLinked to original sources
PubMed1999

Retinal afferents to the dorsal raphe nucleus in rats and Mongolian gerbils.

A direct pathway from the retina to the dorsal raphe nucleus (DRN) has been demonstrated in both albino rats and Mongolian gerbils. Following intraocular injection of cholera toxin subunit B (CTB), a diffuse stream of CTB-positive, fine-caliber optic axons emerged from the optic tract at the level of the pretectum/anterior mesencephalon. In gerbils, CTB-positive axons descended ventromedially into the periaqueductal gray, moving caudally and arborizing extensively throughout the DRN. In rats, the retinal-DRN projection comprised fewer, but larger caliber, axons, which arborized in a relatively restricted region of the lateral and ventral DRN. Following injection of CTB into the lateral DRN, retrogradely labeled ganglion cells (GCs) were observed in whole-mount retinas of both species. In gerbils, CTB-positive GCs were distributed over the entire retina, and a nearest-neighbor analysis of CTB-positive GCs showed significant regularity (nonrandomness) in their distribution. The overall distribution of gerbil GC soma diameters ranged from 8 to 22 micrometer and was skewed slightly towards the larger soma diameters. Based on an adaptive mixtures model statistical analysis, two Gaussian distributions appeared to comprise the total GC distribution, with mean soma diameters of 13 (SEM +/-1.7) micrometer, and 17 (SEM +/-1.5) micrometer, respectively. In rats, many fewer CTB-positive GCs were labeled following CTB injections into the lateral DRN, and nearly all occurred in the inferior retina. The total distribution of rat GC soma diameters was similar to that in gerbils and also was skewed towards the larger soma diameters. Major differences observed in the extent and configuration of the retinal-DRN pathway may be related to the diurnal/crepuscular vs. nocturnal habits of these two species.

Animals↗
PubMed1999

Topographic organization of serotonergic dorsal raphe neurons projecting to the superior colliculus in the Mongolian gerbil (Meriones unguiculatus).

Recent evidence suggests that the dorsal raphe nucleus (DRN) of the brainstem is a collection of neuronal clusters having different neurochemical characteristics and efferent projection patterns. To gain further insight into the neuroanatomic organization of the DRN, neuronal populations projecting to the superior colliculus (SC) were mapped in a highly visual rodent, the Mongolian gerbil (Meriones unguiculatus). Retrograde tracers Fluoro-Gold (FG) or cholera toxin subunit-B (CTB) were injected into the superficial layers of the SC, and serotonin (5-hydroxytryptamine, 5-HT) -positive cells were identified by using immunocytochemistry in the FG-injected animals. Based on its projections to the SC, the DRN was divided into five rostrocaudal levels. In the rostral and middle levels of the DRN, virtually all FG-filled cells occurred in the lateral DRN, and 36-55% of 5-HT-immunoreactive (5-HT-ir) cells were also double-labeled with FG. Caudally, FG-filled cells occurred in the lateral, ventromedial, and interfascicular DRN; and 44, 12, and 31% of 5-HT-ir cells, respectively, were also FG-filled. The dorsomedial DRN contained only a small proportion of FG-filled cells at its most caudal level and was completely devoid of FG-filled cells more rostrally. The CTB-injected animals showed a similar distribution of retrogradely labeled cells in the DRN. Topographically, the dorsal tegmental nucleus and the laterodorsal tegmental nucleus appeared to be closely associated with 5-HT-ir cells in the caudal DRN. These results suggest that the lateral DRN and the ventromedial/interfascicular DRN may be anatomically, morphologically, and neurochemically unique subdivisions of the gerbil DRN.

Animals↗
PubMed1978

Effects of feeding Oxytropis and Astragalus pollen to mice and Astragalus seeds to rats.

Pollens collected from Astragalus lentiginosus and Oxytropis sericea were fed to mice. At the end of the feeding period, uterine weights were taken to determine estrogenic activity, and tissue was collected for microscopic examination. The pollen from A lentiginosus, but not from O sericea, induced lesions similar to those of locoweed poisoning. The pollen from neither plant was estrogenic. Seeds from A lentiginosus produced toxicosis when fed to rats.

Animals↗
PubMed1972

Estrogenic properties of locoweed (Astragalus lentiginosus).

Locoweed, Astragalus lentiginosus was extracted with ether (EE) and water (WE). These and the plant residue were mixed with basal diet (BD) and fed to weanling female mice to determine the plant's estrogenic activity. Diethylstilbesterol (DES) was fed as a control. Uterine weight was taken at five to seven days. Three feeding trials were conducted. In Trial 1 one group of mice was fed a basal diet and one group the basal diet plus EE 1 gm/mouse. The uteri from mice receiving EE were heavier (P <.01) than from those receiving BD. In Trial 2 mice were fed 0.10 gmEE/mouse, 0.15 gm EE/mouse, 0.10 and 0.15 microg DES/mouse and basal diet. The uteri from the DES fed mice were heavier (P <.01) than the others. The uteri from the EE mice and the BD mice were lighter than those of the DES mice, but there was no difference between the uteri from the EE and BD. This was thought to be due to the level of EE fed. In Trial 3 three levels of EE, 1.30, 0.86, and 0.42 gm/mouse, two levels of DES, 0.075 and 0.150 microg/mouse, one level water extract, 3 gm/mouse, plant residue, 3 gm/mouse, and basal diet were fed. The uteri from EE mice were heavier (P <.01) than the DES and DES heavier (P <.01) than WE or BD fed mice. Lesions typical of locoweed poisoning were found in WE fed mice. It was concluded that locoweeds contain high levels of estrogenic compounds as well as those causing pathological lesions.

Administration, Oral↗
PubMedDate not supplied

Striate cortex increases contrast gain of macaque LGN neurons.

Recurrent projections comprise a universal feature of cerebral organization. Here, we show that the corticofugal projections from the striate cortex (VI) to the lateral geniculate nucleus (LGN) robustly and multiplicatively enhance the responses of parvocellular neurons, stimulated by gratings restricted to the classical receptive field and modulated in luminance, by over two-fold in a contrast-independent manner at all but the lowest contrasts. In the equiluminant plane, wherein stimuli are modulated in chromaticity with luminance held constant, such enhancement is strongly contrast dependent. These projections also robustly enhance the responses of magnocellular neurons but contrast independently only at high contrasts. Thus, these results have broad functional significance at both network and neuronal levels by providing the experimental basis and quantitative constraints for a wide range of models on recurrent projections and the control of contrast gain.

Animals↗