title: Tyrosine hydroxylase-like and dopamine beta-hydroxylase-like immunoreactivity in the gustatory zone of the nucleus of the solitary tract in the hamster: light- and electron-microscopic studies.
abstract: A quantitative electron-microscopic analysis has been conducted on the neurons within the gustatory zone of the nucleus of the solitary tract of the hamster. The most common group of neurons within the gustatory zone contains both large (X1) and small (X3) members that possess deeply invaginated nuclear profiles. These neurons have somal areas that average 113 micron2 (range 34-281 micron2) and a value of somal area/nuclear area that averages 2.2. Other large and small neurons that have non-invaginated nuclear profiles are also observed. The larger (X2) neurons average 151 micron2 (range 49-487 micron2) and have much cytoplasm and associated membranous organelles that is reflected in a mean value of somal area/nuclear area of 2.6. Members of the X2 group are the largest neurons in the gustatory zone. The smaller (X4) group contains the smallest neurons in the gustatory zone of the nucleus of the solitary tract, averages 50 micron2 (range 16-103 micron2), shows almost no perinuclear cytoplasm and has a mean value of somal area/nuclear area of only 1.5. These findings are consistent with and expand upon the results of similar studies at the light-microscopic level. This grouping has been used to explore the association of tyrosine hydroxylase-like and dopamine beta-hydroxylase-like immunoreactivities with specific populations of neurons that are known to be distributed across the various levels of the gustatory zone. At the light-microscopic level, numerous well-defined and intensely labelled tyrosine hydroxylase-like immunoreactive somata of various morphologies and sizes are observed. Quantification at the electron-microscopic level indicates that 10-15% of the neurons encountered in the dorsal and intermediate levels of the gustatory zone are immunoreactive. The ventral level of the gustatory zone contains few immunoreactive neurons. Tyrosine hydroxylase-like immunoreactive neurons possess either non-invaginated or invaginated nuclear profiles and their somal areas average 106 and 142 micron2, respectively. On the bases of size and ultrastructural features, these immunoreactive somata are assigned to the two groups (X1 and X2) of large neurons within the gustatory portion of the nucleus of the solitary tract. In general, small neurons are not immunoreactive. The distribution of dopamine beta-hydroxylase-like immunoreactivity has also been examined in adjacent sections in order to reveal the presence of any putative noradrenergic neurons in the gustatory zone.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Cell Biology and Anatomy, University of Alabama, Birmingham 35294.
authors.forename: B J
authors.initials: BJ
authors.lastname: Davis
authors.forename: T
authors.initials: T
authors.lastname: Jang
mesh_terms: D000818:Animals; D006224:Cricetinae; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000201:enzymology* / Q000502:physiology / Q000648:ultrastructure; D008854:Microscopy, Electron; D009474:Neurons / Q000145:classification / Q000201:enzymology* / Q000502:physiology; D051381:Rats; D013649:Taste / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase