Coexpression of dynorphin and neurokinin B immunoreactivity in the rat hypothalamus: Morphologic evidence of interrelated function within the arcuate nucleus

Michelle C. Burke, Penny A. Letts, Sally J. Krajewski, Naomi E Rance

Research output: Contribution to journalArticle

178 Citations (Scopus)

Abstract

Considerable evidence suggests that dynorphin and neurokinin B (NKB) neurons in the hypothalamic arcuate nucleus participate in the sex-steroid regulation of reproduction. In the present study, we used dual-label immunofluorescence to explore the distribution of prodynorphin and proNKB immunoreactivity in the rat hypothalamus. Additionally, we investigated whether arcuate prodynorphin-ir (immunoreactive) neurons expressed the neurokinin 3 receptor (NK3R) or nuclear estrogen receptor-α (ERα). We found that the majority of prodynorphin-ir neurons in the rat arcuate nucleus expressed proNKB, whereas nearly all (99%) of the proNKB neurons were immunoreactive for prodynorphin. The arcuate nucleus was the only site in the hypothalamus where neuronal somata coexpressing prodynorphin and proNKB-immunoreactivity were identified. A dense plexus of double-labeled prodynorphin/proNKB-ir fibers was found within the arcuate nucleus extending to the median eminence and throughout the periventricular zone of the hypothalamus. Prodynorphin/proNKB fibers were also identified in the paraventricular nucleus, anterior hypothalamic area, medial preoptic area, median preoptic nucleus, anteroventrai periventricular nucleus, and bed nucleus of the stria terminalis in a distribution consistent with previously described arcuate nucleus projections. Interestingly, the majority of prodynorphin-ir neurons in the arcuate nucleus expressed NK3R, and nearly 100% of the prodynorphin-ir neurons contained nuclear ERa. Our results suggest that there is a close functional relationship between dynorphin and NKB peptides within the arcuate nucleus of the rat, which may include an autofeedback loop mediated through NK3R. The diverse hypothalamic projections of fibers expressing both prodynorphin and proNKB provide evidence that these neurons may participate in a variety of homeostatic and neuroendocrine processes.

Original languageEnglish (US)
Pages (from-to)712-726
Number of pages15
JournalJournal of Comparative Neurology
Volume498
Issue number5
DOIs
StatePublished - Oct 10 2006

Fingerprint

Neurokinin B
Arcuate Nucleus of Hypothalamus
Hypothalamus
Neurokinin-3 Receptors
Neurons
Preoptic Area
Anterior Hypothalamic Nucleus
rimorphin
preproenkephalin
Septal Nuclei
Median Eminence
Paraventricular Hypothalamic Nucleus
Carisoprodol
Estrogen Receptors
Fluorescent Antibody Technique
Reproduction

Keywords

  • Hypothalamus
  • Luteinizing hormone
  • Opioid
  • reproduction
  • Tachykinin

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Coexpression of dynorphin and neurokinin B immunoreactivity in the rat hypothalamus : Morphologic evidence of interrelated function within the arcuate nucleus. / Burke, Michelle C.; Letts, Penny A.; Krajewski, Sally J.; Rance, Naomi E.

In: Journal of Comparative Neurology, Vol. 498, No. 5, 10.10.2006, p. 712-726.

Research output: Contribution to journalArticle

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abstract = "Considerable evidence suggests that dynorphin and neurokinin B (NKB) neurons in the hypothalamic arcuate nucleus participate in the sex-steroid regulation of reproduction. In the present study, we used dual-label immunofluorescence to explore the distribution of prodynorphin and proNKB immunoreactivity in the rat hypothalamus. Additionally, we investigated whether arcuate prodynorphin-ir (immunoreactive) neurons expressed the neurokinin 3 receptor (NK3R) or nuclear estrogen receptor-α (ERα). We found that the majority of prodynorphin-ir neurons in the rat arcuate nucleus expressed proNKB, whereas nearly all (99{\%}) of the proNKB neurons were immunoreactive for prodynorphin. The arcuate nucleus was the only site in the hypothalamus where neuronal somata coexpressing prodynorphin and proNKB-immunoreactivity were identified. A dense plexus of double-labeled prodynorphin/proNKB-ir fibers was found within the arcuate nucleus extending to the median eminence and throughout the periventricular zone of the hypothalamus. Prodynorphin/proNKB fibers were also identified in the paraventricular nucleus, anterior hypothalamic area, medial preoptic area, median preoptic nucleus, anteroventrai periventricular nucleus, and bed nucleus of the stria terminalis in a distribution consistent with previously described arcuate nucleus projections. Interestingly, the majority of prodynorphin-ir neurons in the arcuate nucleus expressed NK3R, and nearly 100{\%} of the prodynorphin-ir neurons contained nuclear ERa. Our results suggest that there is a close functional relationship between dynorphin and NKB peptides within the arcuate nucleus of the rat, which may include an autofeedback loop mediated through NK3R. The diverse hypothalamic projections of fibers expressing both prodynorphin and proNKB provide evidence that these neurons may participate in a variety of homeostatic and neuroendocrine processes.",
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