Osmotic regulation of hypothalamo-neurointermediate lobe corticotrophin-releasing factor-41 in the rat

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Abstract
We have detected significant amounts of corticotrophin-releasing factor-41 (CRF-41) in the rat hypothalamo-neurointermediate lobe system using a radioimmunoassay and reversed-phase high-performance liquid chromatography. Total amounts of CRF-41 in extracts of median eminence (ME), supraoptic nucleus (SON), paraventricular nucleus (PVN) and neurointermediate lobe (NIL) from control animals were 1076 ± 132, 196 ± 44, 22 ± 7 and 147 ± 50 fmol respectively (means ± s.e.m., n = 6). In animals given 340 mmol NaCl/l instead of tap water to drink for 12 days, no significant changes occurred in the CRF-41 content of the ME, SON or PVN, but CRF-41 content increased more than twofold in the NIL (362 ± 58 fmol). Plasma concentrations of CRF-41 and ACTH in control animals were 23 ± 6 and 51 ± 8 pmol/l respectively. After saline treatment no significant change in plasma CRF-41 was detected (20 ± 8 pmol/l) but concentrations of circulating ACTH were decreased (15 ± 2 pmol/l). The CRF-41 content of both the ME and the NIL was significantly depleted after intracerebroventricular injection of colchicine (414 ± 81 and 34 ± 7 fmol respectively). These data suggest that NIL CRF-41 is of hypothalamic origin and can be regulated by an osmotic stimulus. Journal of Endocrinology (1989) 120, 119–124