Corticotropin Releasing Factor (CRF): Origin and Course of Afferent Pathways to the Median Eminence (ME) of the Rat Hypothalamus

Abstract

8–10 days after making various lesions in the rat hypothalamus, the presence of corticotropin releasing factor (CRF) immunoreactive neural structures was studied in paraffin and vibratome sections with CRF immunocytochemistry. (1) Bilateral anterolateral deafferentation of the medial basal hypothalamus (MBH) caused complete disappearance of CRF immunoreactivity from the median eminence (ME) in brains where the posterior edge of the cut reached the level of the pituitary stalk. A shorter cut resulted in positive immunostaining caudal to the caudal edge of the cut. (2) Unilateral deafferentation of the MBH caused significant decrease in CRF immunostaining in the ipsilateral ME. (3) Unilateral posterolateral deafferentation of the MBH caused no changes in CRF immunostaining in the rostral ME, while fewer CRF-containing processes were observed in the more caudal regions. (4) A horizontal cut ventral to the paraventricular nuclei (PVN) caused a slight decrease in the number of CRF-immunoreactive profiles in the ME. A wider and complete unilateral horizontal cut resulted in a significant decrease in CRF immunoreactivity on the operated side. Following various surgical interventions, hormone accumulation in cell bodies was detected in the paraventricular, periventricular preoptic, dorsomedial, periventricular, lateral and posterior hypothalamic, and premammillary nuclei. Fibers arising from most of these nuclei formed a fan-like projection to the ME. The majority of the CRF-fibers ran through the lateral tract of the fan, and reached the ME by the lateral-basal retrochiasmatic area (LBRCA). Scattered fibers were detected in the lateral-basal hypothalamus as far caudally as the level of the pituitary stalk. Unilateral anterolateral and horizontal cuts did not result in complete disappearance of CRF immunoreactivity from the ipsilateral ME, indicating the existence of CRF-fibers of contralateral origin in the ME.

Local secretion of corticotropin-releasing hormone in the joints of Lewis rats with inflammatory arthritis.

“…Immunoreactive CRH is present in the interomediolateral sympathetic column, particularly in the thoracic and lumbar segments of the spinal cord (22), as well as in the ganglia of the sympathetic chain (23,24), and our work suggests that locally secreted CRH may play a role in the pathological process of adjuvant-induced arthritis. Further studies are needed to evaluate the relative contributions of CRH delivered to the joints by the peripheral nervous system and CRH that is synthesized locally in joint tissues.…”

“…Levine and colleagues ( 18,20,21 ) have demonstrated that both sensory afferent and sympathetic efferent nerve fibers contribute to the severity of inflammatory arthritis. Because CRH is localized to the dorsal sensory and sympathetic interomediolateral columns ofthe spinal cord ( 19,22), as well as to the dorsal root and sympathetic ganglia (23,24), it is reasonable to speculate that neuron-derived CRH, along with SP and other neuropeptides, contributes to the inflammatory process.…”

Immunoreactive corticotropin-releasing hormone and its binding sites in the rat ovary.

“…38,000 g for 10 min, the supernatants were discarded, and the pellets were resuspended to a final concentration of 40 mg tissue wet wt/ml in homogenization buffer. 100 Ml ofthe membrane preparation were then added to a 1.5-ml polypropylene microtube containing 100 Ml of an r/hCRH solution ( 12 concentrations ranging from 0 to 1 MM) and 100 Ml of '251I-Tyr-oCRH (0.2 nM final concentration) in incubation buffer (50 mM Tris-HCl, 10 mM MgCl2, 2 mM EGTA, 0.15% BSA, 100 kallikrein inhibitor units/ml aprotinin, 0.15 mM bacitracin, pH 7.2).…”

The hypothalamus, intrinsic connections and outflow pathways to the endocrine system in relation to the control of feeding and metabolism

“…There is convincing anatomical and physiological evidence that the corticotropin zeleasing factor (CRF) containing cells in the parvocellular paraventricular nucleus, via their projections to the median eminence, constitute the major gateway in the hypothalamic expression of motivational drives and the emotional state. Via this paraventricular projection to the median eminence, releasing factors can activate the secretion of adrenocorticotropic hormone (ACTH) from the posterior pituitary, which in turn leads to the liberation of corticosteroids from the adrenal glands (Lechan et al, 1980;Merchenthaler, 1984;Merchenthaler et al, 1984). A second, though minor, connection that may be included in the neuroendocrine pathway may be the dense DMH projection to the OVLT.…”