Presence of corticotropin in brain of normal and hypophysectomized rats.

Abstract

ABSTRACr Immunoreactive and bioreactive corticotropin (ACTH-like) activities have been detected in the median eminence and remaining medial basal hypothalamus of both normal and hypophysectomized adult male rats: bioreactive ACTH (pg/100 gg of protein) 1028 in median eminence and 1289 in medial basal hypothalamus; immunoreactive ACTH (midportion MATERIALS AND METHODSThe median eminence and medial basal hypothalamus were removed from 16 control and 16 hypophysectomized (10 days postoperatively) adult male Sprague-Dawley rats as previously described (11), as were the other, larger, regions such as the cerebellum, cerebral cortex, thalamus, and hippocampus. The median eminence and medial basal hypothalamus were dissected from frozen sections of the brain; the other areas of the brain were removed from fresh tissue. The medial basal hypothalamus sample consisted of three 3-mm X 3-mm triangles of brain, each one 0.3 mm thick.Hypophysectomy was confirmed by visual inspection of the sellar area at time of sacrifice; additionally, plasma ACTH* concentrations at this time (between 0900 and 1000 hr) were less than 15 pg/ml in all the hypophysectomized animals and ranged from 27 to 153 pg/ml in the control group (1 ml is equivalent to approximately 55 ,sg of protein). Specimens of cortex, hippocampus, thalamus, and cerebellum were also obtained from normal animals (n = 5). All tissues were analyzed in pools comprised of samples from five or six animals.Immediately after removal, tissues were placed in plastic or heavily silicone-treated microhomogenizing tubes kept on ice, and were homogenized in 0.1 M HCl (0.2-0.5 ml/mg wet tImmunoassay (12) was performed on unextracted plasma by using the paradoxical binding phenomenon described by Matsukara et al. (13) and an antibody raised in our laboratory. On a molar basis, the antibody crossreacted equally with porcine ACTH (pACTH), hACTH, and ACTH1-24; a-MSH had approximately 8% crossreactivity. Over the effective range of the standard curve, ACTHI-'0, ACTH1749 (synthetic human sequence), and fl-MSH were undetectable. At a titer of 1/1500, the useful standard dose range was 0-150 pg/ml, with 2-4 pg/ml routinely being significantly different than the zero dose. pACTH 39 was used as a standard and for iodination. Most plasma specimens exhibited parallelism with the standard curve, with acceptable incubation damage to label at plasma concentrations of up to 20% of incubation volume. Plasma was assayed at dilutions of 2-10%. All specimens were assayed in duplicate at multiple dilutions. Ten pools of rat plasma (range, 18-300 pg/ml) were compared in assays with the "paradoxical" antibody and the NH2-terminal antibody provided by the National Institutes of Health (extracted plasma). Levels obtained with the latter averaged 84% of those with the paradoxical antibody, with an average coefficient of variation of 9.7% (r = 0.99; slope = 1.1). 648

Effects of Acute Behavioral Stress on Plasma and Cerebrospinal Fluid ACTH and β-Endorphin in Rhesus Monkeys

“…Considerable evidence indicates that the regula tion, secretion, and function of ACTH and P-E in the brain differ from those in the periphery [8,[19][20][21], ACTH and p-E can also be measured in cerebrospinal fluid (CSF) [15, 24. 31, 35].…”

“…ACTH, and p-endorphin. It is suggested that acute behavioral stress does not alter CSF ACTH or p-endorphin, and that this information may be clinically useful for future human studies of CSF ACTH and P-endorphin in neuropsychiatrie illnesses.Adrenocorticotropic hormone (ACTH) and P-endor phin (P-E) have a common polypeptide precursor, pro opiomelanocortin [23] and are located in the same pituitary cells [5], Once thought to be located exclusively in the pitu itary, ACTH and |5-E have recently been found in the brain [18,19,23]. Considerable evidence indicates that the regula tion, secretion, and function of ACTH and P-E in the brain differ from those in the periphery [8,[19][20][21], ACTH and p-E can also be measured in cerebrospinal fluid (CSF) [15, 24.…”

Immunocytochemical Distribution of Luteinizing Hormone in Rat Central Nervous System

“…The most extensively studied of the anterior pituitary-like pro teins in brain is ACTH. Numerous ¡mmunocytochemical studies [ 1,23,27,30,31,35,[42][43][44]46,47,52,55,60,61] have mapped the distribution of ACTH [for review of other POMC molecules, see 34]. Most ACTH immunoreactive perikarya are found in the same area of the mediobasal hypothalamus [31, 35.…”

Corticotropin and beta-endorphin: construction and analysis of recombinant DNA complementary to mRNA for the common precursor.

“…However, ACTH, f3-endorphin, and enkephalin have been identified in other regions of the brain (10)(11)(12). For instance, in some regions there is material that reacts with antisera to f-endorphin but not to [Met]enkephalin, whereas in other regions, the converse is true (12).…”