The Hypophysiotropic Neurotensin-Immunoreactive Neuronal System of the Rat Brain

Abstract

The present study describes the distribution of hypophysiotropic neurotensin-immunoreactive (NTi) perikarya in the rat hypothalamus. After peripheral administration of the retrograde tracer Fluoro-Gold, NT immunoreactivity was demonstrated with fluorescence immunocytochemistry using Texas red-labeled avidin. The results indicate that approximately 70% of all NTi neurons that are connected to the hypophysial portal system are located in the arcuate nucleus. Approximately 30% of these hypophysiotropic NTi neurons reside in the parvocellular subdivisions of the paraventricular nucleus. Our results also show that both the arcuate and the paraventricular nuclei contain NTi perikarya that do not project to the median eminence.

Expression and localization of the cystic fibrosis transmembrane conductance regulator mRNA and its protein in rat brain.

“…Neurotensin is known to cause anorexia and increased energy expenditure when injected into the central hypothalamus of rats (40,43). Merchenthaler et al has established that 70% of neurotensin-immunoreactive neurons within the arcuate nucleus, the paraventricular area, and the paraventricular nucleus send axons that terminate on portal capillaries of the median eminence (43).…”

“…Merchenthaler et al has established that 70% of neurotensin-immunoreactive neurons within the arcuate nucleus, the paraventricular area, and the paraventricular nucleus send axons that terminate on portal capillaries of the median eminence (43). The regulation and maintenance of homeostatic functions is in part regulated by the pituitary gland and whose function may be affected by the expression of CFTR.…”

Multimodal Influence of Estrogen upon Gonadotropin-Releasing Hormone Neurons

“…Many of these neurons coexpress dopamine and project to the median eminence (301,302) from where NT release has been shown to be regulated by estrogen (303). A role has been proposed for estrogendependent NT release from the median eminence in regulating PRL secretion while its involvement within the GnRH network is unknown (293).…”

Pharmacological Evidence that Neurotensin Mediates Prolactin- Induced Activation of Tuberoinfundibular Dopamine Neurons

“…Although not directly addressed in the present study, the source of NT which mediates the stimulatory effect of prolactin on TIDA neurons is likely to be located within the mediobasal hypothalamus since complete surgical deafferentation of this region from the rest of the brain does not alter the ability of hyperprolactinemia to activate TIDA neurons [12]. Since NT mRNA and immunoreactivity have been localized in neurons within the arcuate nucleus (including those containing tyrosine hydroxylase) [33], prolactin induction of NT synthesis and release could occur in afferent neuropeptidergic neurons [14, 34] and/or in subpopulations of TIDA neurons themselves [35, 36]. …”

“…For example, NT-containing neurons are located in the mediobasal hypothalamic arcuate nucleus [13, 14] and TIDA neurons encode mRNA for high-affinity NT receptors [15]. Furthermore, administration of NT produces a dose-dependent activation of TIDA neurons both in vitro [16, 17] and in vivo [18, 19, 20].…”