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Article: Projections of ventromedial hypothalamic neurons to the midbrain central gray: An ultrastructural study

TitleProjections of ventromedial hypothalamic neurons to the midbrain central gray: An ultrastructural study
Authors
Issue Date1990
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/neuroscience
Citation
Neuroscience, 1990, v. 38 n. 2, p. 395-407 How to Cite?
AbstractVentromedial hypothalamic projections to the midbrain central gray may be involved in the mediation of female reproductive behavior. In order to demonstrate and examine projections of the ventromedial nucleus in the midbrain central gray, in the rat, electrolytic lesions were placed in the ventromedial nucleus and the midbrain central gray was examined for ultrastructural signs of degeneration at various intervals, i.e. 27.5 h and two, four, six and eight days following the lesions. The fine structure of the midbrain central gray of unlesioned animals were also examined to characterize its normal morphology and to establish a baseline with which to compare the effects of the lesion. In unlesioned animals, the neuropil of midbrain central gray contained several synaptic types, with axodendritic synapses appearing to be the most predominant. Dendrites contained well-preserved microtubules. Synaptic endings contained many clear, round vesicles and some contained dense-cord vesicles as well. Neuropil synapses were both asymmetric and symmetric. Cell bodies were characterized by light cytoplasm and had asymmetric and symmetric synapses on their surface. Following electrolytic lesions in the ventromedial nucleus, various types of degenerative patterns were seen in the midbrain central gray, including electron-dense, flocculent, watery, and pinocytotic degeneration. Specific characteristics of degeneration included shrunken, dense axons and endings clumped synaptic vesicles, abnormally large, dark mitochondria, membranous sacs of various sizes, swollen endings with reduced numbers of synaptic vesicles, and endings and processes containing large numbers of coated vesicles. Some of these signs were already evident at 27.5 h following the lesion. In addition, degenerating postsynaptic processes and cell bodies were seen in the midbrain central gray. At 27.5 h survival time, degenerating dendritic processes often appeared swollen, devoid of microtubules, and contained enlarged mitochondria. At longer survival times neuronal degeneration was observed in the midbrain central gray, characterized by electron-dense cell bodies and pycnotic nuclei. Both degenerating pre- and postsynaptic elements appeared to be engulfed by glial processes. Control lesions in non-hypothalamic regions which project to the midbrain central gray, i.e. nucleus gigantocellularis and pontine regicular formation and in a non-projecting region, i.e. parietal cortex, were performed. Lesions in the nucleus gigantocellularis and parietal cortex had virtually no effect on midbrain gray morphology, and lesions in the pontine reticular formation produced only slight degeneration in the midbrain central gray. These results demonstrate the innervation of the midbrain central gray by the ventromedial nucleus and characterize the nature of the ventromedial hypothalamic projections in the midbrain central gray at the fine structural level. These projections may carry estrogen-dependent signals originating in the ventromedial nucleus to the midbrain central gray.
Persistent Identifierhttp://hdl.handle.net/10722/146614
ISSN
2015 Impact Factor: 3.231
2015 SCImago Journal Rankings: 1.768
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorChung, SKen_HK
dc.contributor.authorPfaff, DWen_HK
dc.contributor.authorCohen, RSen_HK
dc.date.accessioned2012-05-08T03:21:16Z-
dc.date.available2012-05-08T03:21:16Z-
dc.date.issued1990en_HK
dc.identifier.citationNeuroscience, 1990, v. 38 n. 2, p. 395-407en_HK
dc.identifier.issn0306-4522en_HK
dc.identifier.urihttp://hdl.handle.net/10722/146614-
dc.description.abstractVentromedial hypothalamic projections to the midbrain central gray may be involved in the mediation of female reproductive behavior. In order to demonstrate and examine projections of the ventromedial nucleus in the midbrain central gray, in the rat, electrolytic lesions were placed in the ventromedial nucleus and the midbrain central gray was examined for ultrastructural signs of degeneration at various intervals, i.e. 27.5 h and two, four, six and eight days following the lesions. The fine structure of the midbrain central gray of unlesioned animals were also examined to characterize its normal morphology and to establish a baseline with which to compare the effects of the lesion. In unlesioned animals, the neuropil of midbrain central gray contained several synaptic types, with axodendritic synapses appearing to be the most predominant. Dendrites contained well-preserved microtubules. Synaptic endings contained many clear, round vesicles and some contained dense-cord vesicles as well. Neuropil synapses were both asymmetric and symmetric. Cell bodies were characterized by light cytoplasm and had asymmetric and symmetric synapses on their surface. Following electrolytic lesions in the ventromedial nucleus, various types of degenerative patterns were seen in the midbrain central gray, including electron-dense, flocculent, watery, and pinocytotic degeneration. Specific characteristics of degeneration included shrunken, dense axons and endings clumped synaptic vesicles, abnormally large, dark mitochondria, membranous sacs of various sizes, swollen endings with reduced numbers of synaptic vesicles, and endings and processes containing large numbers of coated vesicles. Some of these signs were already evident at 27.5 h following the lesion. In addition, degenerating postsynaptic processes and cell bodies were seen in the midbrain central gray. At 27.5 h survival time, degenerating dendritic processes often appeared swollen, devoid of microtubules, and contained enlarged mitochondria. At longer survival times neuronal degeneration was observed in the midbrain central gray, characterized by electron-dense cell bodies and pycnotic nuclei. Both degenerating pre- and postsynaptic elements appeared to be engulfed by glial processes. Control lesions in non-hypothalamic regions which project to the midbrain central gray, i.e. nucleus gigantocellularis and pontine regicular formation and in a non-projecting region, i.e. parietal cortex, were performed. Lesions in the nucleus gigantocellularis and parietal cortex had virtually no effect on midbrain gray morphology, and lesions in the pontine reticular formation produced only slight degeneration in the midbrain central gray. These results demonstrate the innervation of the midbrain central gray by the ventromedial nucleus and characterize the nature of the ventromedial hypothalamic projections in the midbrain central gray at the fine structural level. These projections may carry estrogen-dependent signals originating in the ventromedial nucleus to the midbrain central gray.en_HK
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/neuroscienceen_HK
dc.relation.ispartofNeuroscienceen_HK
dc.subject.meshAnimalsen_US
dc.subject.meshFemaleen_US
dc.subject.meshMedulla Oblongataen_US
dc.subject.meshMesencephalon - Physiology - Ultrastructureen_US
dc.subject.meshMicroscopy, Electronen_US
dc.subject.meshNeurons - Physiology - Ultrastructureen_US
dc.subject.meshParietal Lobe - Physiologyen_US
dc.subject.meshPeriaqueductal Gray - Physiology - Ultrastructureen_US
dc.subject.meshPonsen_US
dc.subject.meshRatsen_US
dc.subject.meshRats, Inbred Strainsen_US
dc.subject.meshReticular Formation - Physiologyen_US
dc.subject.meshSynaptic Transmissionen_US
dc.subject.meshTime Factorsen_US
dc.subject.meshVentromedial Hypothalamic Nucleus - Cytology - Physiologyen_US
dc.titleProjections of ventromedial hypothalamic neurons to the midbrain central gray: An ultrastructural studyen_HK
dc.typeArticleen_HK
dc.identifier.emailChung, SK:skchung@hkucc.hku.hken_HK
dc.identifier.authorityChung, SK=rp00381en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/0306-4522(90)90037-5en_HK
dc.identifier.pmid2175855-
dc.identifier.scopuseid_2-s2.0-0025015371en_HK
dc.identifier.volume38en_HK
dc.identifier.issue2en_HK
dc.identifier.spage395en_HK
dc.identifier.epage407en_HK
dc.identifier.isiWOS:A1990EE09100010-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridChung, SK=7404292976en_HK
dc.identifier.scopusauthoridPfaff, DW=36046651600en_HK
dc.identifier.scopusauthoridCohen, RS=35560739900en_HK

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