A direct neuronal connection between the subparafascicular and ventrolateral arcuate nuclei in non-lactating female rats. Could this pathway play a role in the suckling-induced prolactin release?
The neuronal pathways, through which prolactin secretion is regulated during lactation, have still not been fully explored. Studies indicate that the suckling stimulus travels through the spinal cord, the brain stem, and then reaches the hypothalamus. The focus of this present experiment is to further explore the neuronal connections between the brain stem and the arcuate nucleus that may be involved in suckling-induced prolactin release. Ante- and retrograde tracing techniques were used. To chemically characterize the explored neurons neuropeptide immunohistochemistry was applied. Previous studies have indicated that the peripeduncular nucleus is a relay of the suckling stimulus in the midbrain, conveying the information to the hypothalamus. In our experiments, we have found an additional cell group in the subparafascicular parvocellular nucleus located just behind the posterior thalamus that projects to the arcuate neurons. The injection of the retrograde tracer into the ventrolateral part of the arcuate nucleus labeled cells in the lateral subdivision of the subparafascicular parvocellular nucleus. Anterograde tracing from the subparafascicular parvocellular nucleus resulted in fiber labeling in the arcuate nucleus in close apposition with dynorphin immunopositive neurons. Double labeling revealed that a subpopulations of the subparafascicular parvocellular neurons projecting to the arcuate nucleus contained tuberoinfundibular peptide of 39 residues or calcitonin gene-related peptide. The presented findings suggest that the ascending fibers from the subparafascicular parvocellular nucleus might be in the pathway involved in the suckling-induced prolactin release.
Department of Pediatrics, University of Kentucky, Lexington, KY, USA. fkszabo@gmail.com
Flora K
FK
Szabo
Natalie
N
Snyder
Ted B
TB
Usdin
Gloria E
GE
Hoffman
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000033:anatomy & histology / Q000502:physiology*; D001710:Biotin / Q000031:analogs & derivatives; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D003911:Dextrans; D004399:Dynorphins / Q000378:metabolism; D005260:Female; D019004:Galanin / Q000378:metabolism; D007034:Hypothalamus, Posterior / Q000033:anatomy & histology / Q000502:physiology*; D007150:Immunohistochemistry; D009434:Neural Pathways / Q000502:physiology*; D056347:Neuroanatomical Tract-Tracing Techniques; D056325:Neuronal Tract-Tracers; D009474:Neurons / Q000145:classification / Q000502:physiology; D009479:Neuropeptides / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013266:Stilbamidines; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D003911:Dextrans; C489169:Gal protein, rat; D056325:Neuronal Tract-Tracers; D009479:Neuropeptides; D011498:Protein Precursors; D013266:Stilbamidines; C076397:biotinylated dextran amine; C400136:tuberoinfundibular peptide 39; D001710:Biotin; D004399:Dynorphins; D019004:Galanin; D011388:Prolactin; D014446:Tyrosine 3-Monooxygenase; D015740:Calcitonin Gene-Related Peptide