Immunoreactive Corticotropin-Releasing Hormone in the Hypothalamoinfundibular Tract

Abstract

Ovine corticotropin-releasing hormone (CRF)-like immunoreactivity has been examined in the rat hypothalamus by light microscopy. Immunoreactivity was found in nerve fibers of the median eminence, mainly in the external zone around the portal vessels. In rats pretreated with colchicine or with hypothalamic knife cuts, small to moderate sized cells with two (bipolar) or rarely more (multipolar) dendrites, showing CRF-like immunoreactivity were present in the antierior and medial parvocellular subdivisions of the paraventricular nucleus. Scattered CRF-like immunopositive cells were found in the periventricular and medial preoptic nuclei. CRF-like immunoreactivity was clearly enhanced in the median eminence and paraventricular nucleus 8–10 days after bilateral adrenalectomy. A variety of hypothalamic transections had to be performed to determine reliably the topography of CRF-like nerve fibers projecting to the stalk-median eminence. Ax-ons left the paraventricular nucleus in a lateral direction, turned ventrally in the lateral hypothalamus then medially as they approached the base of the hypothalamus above and behind the optic chiasm (lateral retrochiasmatic area). Fibers reached the median eminence by traveling caudally and medially from the rostral half of the lateral retrochiasmatic area. Scattered fibers were present in the retroinfundibular (posterior) portion of the median eminence. No immunoreactive fibers remained in the stalk-median eminence 1 or 4 weeks after transection of that loop-like pathway of CRF-containing fibers in the lateral retrochiasmatic area.

Immunohistochemical evidence against the coexistence of a corticotropin-releasing factor and oxytocin or vasopressin in the rat paraventricular nucleus.

“…They used serial 5 pm paraffin sections, a thickness which might enable comparison between the two consecutive sections, though they did not present a comparison precise enough in their paper. The results of the present study are in agreement with those of ANTONI et al (1983).…”

“…On the other hand, ANTONI et al (1983) presented evidence that anti-CRF-reactive cells were different from those stained by anti-AVP, antineurophysin and anti-TRH. They used serial 5 pm paraffin sections, a thickness which might enable comparison between the two consecutive sections, though they did not present a comparison precise enough in their paper.…”

“…A corticotropin-releasing factor (CRF Since the purification and determination of the amino acid sequence of CRF (VALE et al, 1981), some immunohistochemical studies on the localization of CRF neurons in the hypothalamus have been accomplished in rats (MERcHENTHALER et al, 1982;ANTONI et al, 1983;BURLET et al, 1983;KAWATA et al, 1983;SWANSON et al, 1983;TRAMU et al, 1983) and some other mammals (KAWATA et al, 1982). In these reports, it has been debated whether or not CRF and arginine-vasopressin (AVP) or CRF and oxytocin (OXT) might exist in the same neurons.…”

“…In these reports, it has been debated whether or not CRF and arginine-vasopressin (AVP) or CRF and oxytocin (OXT) might exist in the same neurons. BURLET et al (1983), SWANSON et al (1983), andTRAMU et al (1983) argued for the coexistence of CRF and one of these posterior pituitary hormones, while ANTONI et al (1983) andMERCHENTHALER et al (1982) denied it. These findings were based on the results of comparisons between adjacent serial sections stained immunohistochemically with anti-CRF and anti-OXT (or anti-AVP) sera, respectively.…”

Hypersecretion of corticotrophin-releasing hormone and arginine vasopressin in hypothyroid male rats as estimated with push-pull perfusion

“…Adrenalectomy markedly increases the levels of CRH and AVP immunoreactivity (Antoni et al 1983, Paull & Gibbs 1983, Kiss et al 1984, and the amount of mRNA transcripts of CRH and AVP gene (Wolfson et al 1985, Antoni 1986, Davis et al 1986 in the neurons of the PVN which contains glucocorticoid receptors in rats (Reul & De Kloet 1985). It has also been reported that adrenalectomy increases the concentration of CRH and AVP in hypophysial portal blood (Oliver et al 1983, Kooy et al 1990) and the median eminence (Suda et al 1983, Holmes et al 1986).…”