Vasoactive Intestinal Peptide Efferent Projections of the Suprachiasmatic Nucleus in Anterior Hypothalamic Transplants: Correlation with Functional Restoration of Circadian Behavior

Nov 1, 1995Experimental neurology

Brain signals from the body’s main clock to the front hypothalamus in transplants linked to restoring daily activity rhythms

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

A dense aggregation of vasoactive intestinal peptide (VIP) neurons was found in transplants that restored behavioral rhythmicity in hosts.

Transplantation of fetal anterior hypothalamic tissue containing the suprachiasmatic nucleus (SCN) can restore circadian rhythmicity in hosts made arrhythmic by SCN ablation.
Identification of SCN-derived VIP fibers in host terminal fields suggests integration of transplant-derived signals with the host brain.
Restoration of circadian locomotor activity correlates with VIP innervation in the host's paraventricular thalamic nucleus (PVT).
No significant differences were observed in the VIP projections from homografts compared to heterografts.

AI simplified

Circadian rhythmicity can be restored by transplantation of fetal anterior hypothalamic (AH) tissue containing the suprachiasmatic nucleus (SCN) into hosts rendered arrhythmic by SCN ablation. However, the nature of the SCN effector pathways mediating functional recovery has remained elusive. To examine implant-derived SCN innervation of the host, AH homografts (hamster-to-hamster) and heterografts (mouse- or rat-to-hamster) were employed and the distribution of vasoactive intestinal peptide (VIP) within the SCN terminal fields was evaluated. A comparison was made between cases where circadian locomotor activity was restored and cases where circadian rhythmicity remained disrupted following AH transplantation. A dense aggregation of VIP neurons and processes was identified in each transplant that restored behavioral rhythmicity in the host. In these cases, SCN-derived VIP fibers were integrated with the host brain and could be identified in host terminal fields typically innervated by SCN-VIP fibers. A correlation was noted between VIP innervation of the host paraventricular thalamic nucleus (PVT) and restoration of circadian rhythmicity. Neither qualitative nor quantitative differences in transplant VIP projections were noted between AH homografts and heterografts. These results demonstrate that SCN VIP neurons in AH transplants send an appropriately restricted set of efferent projections to the host brain and suggest that SCN efferent projections to the PVT may participate in mediating the functional recovery of circadian locomotor activity.

Full Text

Full text is available at the source.

View full text (XML) ↗View full text ↗

Vasoactive Intestinal Peptide Efferent Projections of the Suprachiasmatic Nucleus in Anterior Hypothalamic Transplants: Correlation with Functional Restoration of Circadian Behavior

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief