Synaptic inputs of tachykinin-containing nerve terminals to target tyrosine-hydroxylase-, beta-endorphin- and neuropeptide Y-producing neurons of the arcuate nucleus. Double pre-embedding immunocytochemical study in the rat.
Anatomical connections between tachykinin-containing terminals and three neuronal populations of the arcuate nucleus, chemically defined respectively by beta-endorphin (beta-END), tyrosine-hydroxylase or neuropeptide Y (NPY) and well represented in the arcuate nucleus, were studied using electron microscope double pre-embedding immunocytochemistry involving a combination of two sensitive chromogens: diaminobenzidine and tetramethylbenzidine. Following tachykinin immunodetection by diaminobenzidine, and tyrosine-hydroxylase, beta-END or NPY immunolabelling by tetramethylbenzidine, tachykinin-immunoreactive terminals were seen presynaptic to tyrosine-hydroxylase immunopositive cells and dendrites principally in the dorsomedial portion of the arcuate nucleus. Tachykinin-immunoreactive processes were also seen in synaptic contact with ventrolaterally located beta-END immunopositive perikarya. Tachykinin-immunopositive terminals also contacted NPY-immunoreactive cells and dendritic processes ventromedially. These results demonstrate the existence of a direct tachykinergic input onto three neuronal populations expected to play a role in the control of reproductive events. Consequently, they suggest, at least, an indirect action for tachykinins in the regulation of reproduction. Especially, tachykinins may indirectly control the luteinizing hormone-releasing hormone neurons via dopamine, beta-END and NPY cells and thereby influence luteinizing hormone secretion.
Magoul
R
R
Laboratoire de Neurocytochimie Fonctionnelle, URA CNRS, Talence, France.
Dubourg
P
P
Benjelloun
W
W
Tramu
G
G
D015100:3,3'-Diaminobenzidine; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D001560:Benzidines; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D009474:Neurons / Q000201:enzymology / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000378:metabolism / Q000648:ultrastructure; D009478:Neuropeptide Y / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D015320:Tachykinins / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D001615:beta-Endorphin / Q000378:metabolism
D001560:Benzidines; D009478:Neuropeptide Y; D015320:Tachykinins; D015100:3,3'-Diaminobenzidine; C021758:3,3',5,5'-tetramethylbenzidine; D001615:beta-Endorphin; D014446:Tyrosine 3-Monooxygenase