Studying neurotransmitter systems to understand the development and function of sex differences in the brain: the case of vasopressin

The aim of the present study was to describe the ultrastructure of neurons (from eight animals) and to analyse the synaptic terminal distribution (from two animals) in the posterodorsal subnucleus of the medial amygdala (MePD) of adult male rats. Using transmission electron microscopy, it was possible to identify many spiny and aspiny dendrites, unmyelinated axonal bundles, single axonal processes, a few myelinated axons, blood vessels and glial processes in the neuropil. Axodendritic synapses were the most frequently observed (67.5%), appearing to be of either the inhibitory or the excitatory types. The presynaptic region contained round or flattened vesicles that occurred either singly or with dense-cored vesicles (DCVs). The dendrites often received many synapses on a single shaft, and axon terminals displayed synaptic contacts with one or more postsynaptic structures. Dendritic spines showed different morphologies and the synapses on them (23.1%) formed a single and apparently excitatory synaptic contact with round, electron-lucid vesicles alone or, less frequently, with DCVs. Inhibitory and excitatory axosomatic synapses (8.2%) and excitatory axoaxonic synapses (1.2%) were also identified. The present report provides new findings relevant to the study of the MePD cellular organization and could be combined with other morphological data in order to reveal the functional activity of this area in male rats.

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“…1985; Micevych et al. 1988; De Vries, 1995; Veinante & Freund‐Mercier, 1997; Wilson et al. 2002; for reviews, see Gloor, 1997; de Olmos et al.…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural features of neurons and synaptic contacts in the posterodorsal medial amygdala of adult male rats

Hermel¹,

Faccioni-Heuser

Marcuzzo³

et al. 2006

Journal of Anatomy

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“…These comparisons involve animals that differ in both circulating gonadal steroid levels and in behavior. Expression of AVT and its mammalian homologue, arginine vasopressin (AVP), in the central nervous system are strongly dependent on gonadal androgens in many species [reviewed in Moore, 1992;De Vries, 1995]. Arginine vasopressin message and protein are sexually dimorphic in the hypothalamus of rats [DeVries et al, 1984[DeVries et al, , 1992[DeVries et al, , 1994.…”

Section: Discussionmentioning

confidence: 99%

Hypothalamic Arginine Vasotocin mRNA Abundance Variation Across Sexes and with Sex Change in a Coral Reef Fish

et al. 2000

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Gonadal hormones are important mediators of sexual and aggressive behavior in vertebrates. Recent evidence suggests that the peptide hormones arginine vasotocin (AVT) and its mammalian homologue arginine vasopressin (AVP) often critically mediate these gonadal hormone effects on behavior and have direct influences on behavioral variation. Behavioral differences between sexes, across reproductive states, and even among closely related species are correlated with differences in central AVT/AVP systems in many species. We report differences in hypothalamic AVT mRNA levels between distinct alternate male phenotypes and with female-to-male sex change in the bluehead wrasse (Thalassoma bifasciatum), a teleost fish. The aggressively dominant and strongly courting male phenotype has greater numbers of AVT mRNA producing cells in the magnocellular preoptic area of the hypothalamus than females. Levels of AVT mRNA within these cells in dominant males are also approximately three times female levels whereas the non-aggressive male phenotype has AVT mRNA levels approximately twice female levels. Behavioral sex change is very rapid in this species and is not dependent on the presence of gonads. Conversely, rapid increases in sexual and aggressive behavior during sex change are closely paralleled by approximate fourfold increases in hypothalamic AVT-mRNA levels. The behavioral plasticity shown by bluehead wrasses in response to social environment might be mediated in part by a neuropeptide, AVT, with changes in the gonads and gonadal hormones as the result rather than the cause of behavioral dominance.

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“…In particular, the quail POM has been identified as a key region controlling male copulatory behavior . An important role for central steroid-sensitive VP/VT pathways in the control of sexual behaviors has been identified in mammals (Södersten et al, 1986;Smock et al, 1992; for review, see De Vries, 1995) and in amphibians (for reviews, see Moore, 1992;Moore et al, 1994;.…”

Section: Potential Roles Of the Central Vt Systemmentioning

confidence: 99%

Central vasotocin-immunoreactive system in a male passerine bird (Junco hyemalis)

et al. 1999

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Studying neurotransmitter systems to understand the development and function of sex differences in the brain: the case of vasopressin

Abstract: Printed in the United States of America Library of Congress Cataloging-in-Publication Data

Cited by 13 publications

References 83 publications

Ultrastructural features of neurons and synaptic contacts in the posterodorsal medial amygdala of adult male rats

Ultrastructural features of neurons and synaptic contacts in the posterodorsal medial amygdala of adult male rats

Hypothalamic Arginine Vasotocin mRNA Abundance Variation Across Sexes and with Sex Change in a Coral Reef Fish

Central vasotocin-immunoreactive system in a male passerine bird (Junco hyemalis)

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