Fos protein-like immunoreactivity in the hypothalamus: Normal development and the effects of cold ambient temperature and early eye opening in the preweanling rat.
Item
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Title
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Fos protein-like immunoreactivity in the hypothalamus: Normal development and the effects of cold ambient temperature and early eye opening in the preweanling rat.
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Identifier
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AAI9315474
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identifier
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9315474
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Creator
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Joyce, Myra P.
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Contributor
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Adviser: Gordon A. Barr
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Date
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1993
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Developmental | Psychology, Physiological
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Abstract
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Hypothalamic nuclei mediate diverse physiological and behavioral activities. The cellular activity that mediates behavior occurs at specific times during development. This activity can be associated with changes in gene transcription, metabolic activity, or neuronal depolarization.;Visualization of Fos, the gene product of the c-fos proto-oncogene, by immunocytochemical methods was used in this study to examine hypothalamic activity. In the first experiment, the development of Fos in rat hypothalami was investigated. The results showed that Fos-positive labeling initially occurs at specific times during development in different nuclei. This suggests that neuronal activation or gene transcription for hormone synthesis, may be initiated at specific ages.;The second experiment examined the hypothalamic response to cold temperature during development. Rat pups were placed in a 15{dollar}\sp\circ{dollar}C environment for one hour, then immediately sacrificed for Fos immunocytochemistry. Labeled nuclei were first seen in the preoptic area at 10 days and in the anterior hypothalamic nucleus at 21 days. At these ages, the drop in rectal temperatures of the animals after one hour in the cold were reduced. This suggests that these hypothalamic neurons are activated coincidentally with the appearance of a thermogenic response.;The third experiment examined the development of Fos-LI in the suprachiasmatic nuclei (SCN) and compared the appearance of Fos-LI within the SCN to the anatomical development of the nucleus. In addition, the GABA{dollar}\sb{lcub}\rm B{rcub}{dollar} receptor agonist, baclofen, was administered to 14-day-old rats to clarify the functional interactions within the nucleus. At 4-days-of-age Fos-LI labeled nuclei are first seen in the ventrolateral SCN. The labeling increases and peaks by 10-days-of-age, coincidental with the completion of synaptogenesis. The nuclei in the ventrolateral portion of the caudal SCN are more intensely labeled than those in the dorsomedial region. By 60-days, the density and intensity of Fos-LI nuclei decrease substantially. Surgical eye-opening of 8-day-old pups had no effect on Fos-LI labeling. This suggests that the Fos-positive labeling observed in the ventrolateral SCN may be due to spontaneous activity of retinal ganglion cells. Baclofen administration had no effect on the activity of SCN neurons.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
