 |
||||
|
||||
|
||||
|
||||
Previous Article | Next Article
The Journal of Neuroscience, February 15, 1998, 18(4):1546-1558
An Alternate Pathway for Visual Signal Integration into the Hypothalamo-Pituitary Axis: Retinorecipient Intergeniculate Neurons Project to Various Regions of the Hypothalamus and Innervate Neuroendocrine Cells Including Those Producing Dopamine
Tamas L. Horvath Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06520
Using tract tracing and immunocytochemistry, this study explored the connectivity between lateral geniculate efferents and neurons of the hypothalamus, including those producing dopamine, that have direct access to fenestrated capillaries. It was also determined whether the intergeniculate neurons that give rise to hypothalamic projections are targeted by retinal axons.
Within the hypothalamus, Phaseolus vulgaris leucoagglutinin-labeled, lateral geniculate efferents were observed in the suprachiasmatic nucleus, subparaventricular area, periventricular nuclei, medial preoptic areas, and between the arcuate and ventromedial nuclei. In these sites, intergeniculate efferents contacted populations of neurons that were retrogradely labeled from fenestrated capillaries by the intraperitoneal injection of fluorogold. Hypothalamic dopamine neurons, a population of which was neuroendocrine, were also synaptic targets of lateral geniculate efferents. After injection of the retrograde tracer fluorogold into these hypothalamic projection sites in parallel with bilateral enucleation, retrogradely labeled perikarya were restricted to the intergeniculate leaflet. All of the labeled perikarya contained infolded nuclei, and their distal dendrites were frequently found to be contacted by degenerated, retinal fibers.
This study provides morphological evidence for a signaling pathway from the retina through the intergeniculate leaflet to hypothalamic cells that participate in neuroendocrine regulations. These observations raise the possibility that visual signals independent of the circadian clock may also influence the hypothalamo-pituitary axis. In light of the overlapping distribution of intergeniculate and suprachiasmatic efferents in the hypothalamus and their similar relationship with neuroendocrine cells, it is suggested that integration of circadian and visual signals can occur outside of the suprachiasmatic nucleus to regulate endocrine rhythms.
Key words: retina; intergeniculate leaflet; hypothalamus; neuroendocrine cells; dopamine; anterior pituitary
Copyright © 1998 Society for Neuroscience 0270-6474/98/1841546-13$05.00/0
This article has been cited by other articles:
M. Harrington, P. Molyneux, S. Soscia, C. Prabakar, J. McKinley-Brewer, and G. Lall
Behavioral and neurochemical sources of variability of circadian period and phase: studies of circadian rhythms of npy-/- mice
Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2007; 292(3): R1306 - R1314.
[Abstract] [Full Text] [PDF]
L.-Y. Fu, C. Acuna-Goycolea, and A. N. van den Pol
Neuropeptide Y Inhibits Hypocretin/Orexin Neurons by Multiple Presynaptic and Postsynaptic Mechanisms: Tonic Depression of the Hypothalamic Arousal System
J. Neurosci., October 6, 2004; 24(40): 8741 - 8751.
[Abstract] [Full Text] [PDF]
J. S. Menet, P. Vuillez, M. Saboureau, and P. Pevet
Inhibition of hibernation by exercise is not affected by intergeniculate leaflets lesion in hamsters
Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2003; 285(3): R690 - R700.
[Abstract] [Full Text] [PDF]
T. L. Horvath, C. H. Warden, M. Hajos, A. Lombardi, F. Goglia, and S. Diano
Brain Uncoupling Protein 2: Uncoupled Neuronal Mitochondria Predict Thermal Synapses in Homeostatic Centers
J. Neurosci., December 1, 1999; 19(23): 10417 - 10427.
[Abstract] [Full Text] [PDF]
S. Lee, C. K. Kim, and C. Rivier
Nitric Oxide Stimulates ACTH Secretion and the Transcription of the Genes Encoding for NGFI-B, Corticotropin-Releasing Factor, Corticotropin-Releasing Factor Receptor Type 1, and Vasopressin in the Hypothalamus of the Intact Rat
J. Neurosci., September 1, 1999; 19(17): 7640 - 7647.
[Abstract] [Full Text] [PDF]
T. L. Horvath, S. Diano, and A. N. van den Pol
Synaptic Interaction between Hypocretin (Orexin) and Neuropeptide Y Cells in the Rodent and Primate Hypothalamus: A Novel Circuit Implicated in Metabolic and Endocrine Regulations
J. Neurosci., February 1, 1999; 19(3): 1072 - 1087.
[Abstract] [Full Text] [PDF]
G. Legradi and R. M. Lechan
The Arcuate Nucleus Is the Major Source for Neuropeptide Y-Innervation of Thyrotropin-Releasing Hormone Neurons in the Hypothalamic Paraventricular Nucleus
Endocrinology, July 1, 1998; 139(7): 3262 - 3270.
[Abstract] [Full Text] [PDF]
|
|
|
|
 |
|