Morphometric analysis of embryonic rat trigeminal neurons treated with different neurotrophins

The sensory innervation of the lacrimal gland (LG) in the cynomolgous monkey was studied using the retrograde wheat germ agglutinin/horsereadish peroxidase (WGA / HRP) tracer technique. A small solidified piece of WGA / HRP was implanted in the LG. Labelled sensory first-order neurons were found in the ipsilateral trigeminal ganglion (TG) and in the ipsilateral mesencephalic trigeminal nucleus (MTN). The distribution of labelled TG neurons was restricted to ophthalmic and maxillary ganglionic parts. Sensory innervation of LG by primary afferents is not only restricted to TG; an MTN involvement has also been found. This may imply that there is a central sensory role in the production and release of tears.

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“…2003). Moreover, NT‐4 elongates primary sensory TG neurons in culture studies (Ulupinar et al. 2004).…”

Section: Discussionmentioning

confidence: 99%

Connections between the lacrimal gland and sensory trigeminal neurons: a WGA/HRP study in the cynomolgous monkey

Baljet

VanderWerf

2005

Journal of Anatomy

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“…Upon establishing this sequence of development, the effects of dietary sodium restriction on the mechanisms involved in framing gustatory connections can be more thoroughly examined. As an example, one potential method to determine the finer details of the establishment of the gustatory circuitry would involve the use of brain explant cocultures, which are widely employed to study axon-target interactions, differentiation of neuronal phenotypes, and functional connectivity (Grigaliunas et al, 2002;Liu et al, 2004;Ozdinler et al, 2004;Ulupinar et al, 2004). Since many aspects of neural activity can be recapitulated in vitro, biological phenomena that are difficult to tease apart in vivo become more readily accessible in a culture system.…”

Section: Future Studiesmentioning

confidence: 99%

Plasticity of Primary Gustatory Afferents

May

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The first synaptic relay of the gustatory system is located in the brainstem in the nucleus of the solitary tract (NTS). This relay integrates input from three distinct gustatory nerves: the greater superficial petrosal nerve, the chorda tympani nerve, and the glossopharyngeal nerve. However, key information is lacking regarding the anatomical relationships among the terminations of these three nerves. Furthermore, the normal organization of these terminations in the gustatory brainstem is profoundly influenced by dietary sodium restriction during early development. The experiments in this dissertation sought to obtain an accurate characterization of the normal interactions of the three gustatory afferents in the NTS in order to further explore the neural plasticity resulting from early dietary sodium restriction. Chapter II describes a novel, triple-fluorescent confocal microscopy technique implemented to simultaneously visualize the three gustatory terminal fields in the NTS of control and sodium-restricted rats. Under normal developmental conditions, individual gustatory afferents terminated in an ordered yet overlapping array. However, dietary sodium restriction resulted in dramatic and specific alterations of these termination patterns, which increased the extent of convergence of the gustatory terminal fields. Chapter III describes the distinct ultrastructural morphology and synaptic relationships of the axon terminals of the three gustatory afferents in control rats. Chapter IV reveals evidence for plasticity in the synaptic arrangements of all three gustatory afferents as a result of dietary sodium restriction. The results of these three experiments provide new insight on how the circuitry of the gustatory brainstem is wired during distinct phases of development and how they are modified by early dietary III manipulations. These findings provide fundamental information about how taste stimulus information may be functionally processed centrally and how it may be manifested behaviorally. IV DEDICATION To the mentors that have shaped and informed my aspirations, and to the family and friends who have supported my every endeavor, I am most grateful. ACKNOWLEDGEMENTS In a sense, this dissertation project was a collaborative effort in that its completion would not be possible without the concerted encouragement and support of numerous people that surround my life. While there is inevitable risk of omission in compiling a list of such benefactors, I would like to acknowledge a few significant contributions. −My parents, Harry and Barbara May, from whom I learned to balance patience and perseverance in striving to do my best. Thank you both for your unconditional love and support and for providing comic relief with numerous suggestions for experiments I can perform on rats. −My sister and her husband, Heidi and Michael Shaw, for showing never-ending interest in my scientific research (this was a constant source of encouragement) and for giving exceptional advice on every query I presented. −My best friend, Jenni...

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Differential Trk expression in explant and dissociated trigeminal ganglion cell cultures

2005

Self Cite

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During embryonic development, expression of neurotrophin receptor tyrosine kinases (Trks) by sensory ganglia is continuously and dynamically regulated. Neurotrophin signaling promotes selective survival and axonal differentiation of sensory neurons. In embryonic day (E) 15 rat trigeminal ganglion (TG), NGF receptor TrkA is expressed by small diameter neurons, NT-3 receptor TrkC and BDNF receptor TrkB are expressed by large diameter neurons. Organotypic explant and dissociated cell cultures of the TG (and dorsal root ganglia) are commonly used to assay neurotrophin effects on developing sensory neurons. In this study, we compared Trk expression in E15 rat TG explant and dissociated cell cultures with or without neurotrophin treatment. Only a subset of TG cells express each of the three Trk receptors in wholemount explant cultures as in vivo conditions. In contrast, all TG neurons co-express all three Trk receptors upon dissociation, regardless of neurotrophin treatment. Neurons cultured in low concentrations of one neurotrophin first, and switched to higher concentrations of another after 1 day, survive and display morphological characteristics of neurons cultured in a mixture of both neurotrophins for 3 days. Our results indicate that wholemount explant cultures of sensory ganglia represent in vivo conditions in terms of Trk expression patterns; whereas dissociation dramatically alters Trk expression by primary sensory neurons.

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Morphometric analysis of embryonic rat trigeminal neurons treated with different neurotrophins

Cited by 4 publications

References 69 publications

Connections between the lacrimal gland and sensory trigeminal neurons: a WGA/HRP study in the cynomolgous monkey

Connections between the lacrimal gland and sensory trigeminal neurons: a WGA/HRP study in the cynomolgous monkey

Plasticity of Primary Gustatory Afferents

Differential Trk expression in explant and dissociated trigeminal ganglion cell cultures

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