Sex differences in the distribution and projections of testosterone target neurons in the medial preoptic area and the bed nucleus of the stria terminalis of rats.
Retrograde tracing was combined with steroid hormone autoradiography to investigate the projections of testosterone-target neurons in preoptic and limbic regions to the midbrain in male and female rats. Autoradiograms were prepared from the brains of male and female rats that had received an injection of a fluorescent retrograde tracer into the midbrain, and an intravenous injection of [3H]testosterone. Testosterone target neurons that project to the midbrain were abundant in the medial preoptic nucleus (MPN) and bed nucleus of the stria terminalis (BST) and were also observed in the ventromedial nucleus of the hypothalamus. Testosterone target neurons and testosterone target neurons that project to the midbrain were more abundant in the caudal half of the MPN compared to the rostral half. Moreover, male rats had more testosterone target neurons in the caudal MPN than female rats, and the number of testosterone target neurons in the MPN that project to the midbrain was higher in male than in female rats. Male rats also had more testosterone target neurons than females throughout the encapsulated subdivision of the BST. We hypothesize that sex differences in the neuronal connectivity of testosterone target neurons may underly sex specific behavioral responsiveness to androgens.
Lisciotto
C A
CA
Institute of Animal Behavior, Rutgers, State University of New Jersey, Newark 07102, USA.
Morrell
J I
JI
D000818:Animals; D001931:Brain Mapping; D005260:Female; D007031:Hypothalamus / Q000033:anatomy & histology*; D008032:Limbic System / Q000033:anatomy & histology*; D008297:Male; D008636:Mesencephalon / Q000033:anatomy & histology; D009434:Neural Pathways / Q000033:anatomy & histology; D009474:Neurons / Q000648:ultrastructure; D011301:Preoptic Area / Q000033:anatomy & histology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011944:Receptors, Androgen / Q000502:physiology; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology; D013739:Testosterone / Q000502:physiology*; D014697:Ventromedial Hypothalamic Nucleus / Q000033:anatomy & histology
D011944:Receptors, Androgen; D013739:Testosterone