The effect of feeding on cerebrospinal fluid corticotropin-releasing hormone levels in humans

Corticotropin-releasing hormone (CRH) is a neuropeptide thought to play a role in appetite regulation. In this report, we used a serial cerebrospinal fluid (CSF) sampling technique to examine the relationship between CSF CRH, plasma ACTH and cortisol and perceptions of hunger and satiety in fasting and sated volunteers. CSF was withdrawn continuously from 11:00 AM to 5:00 PM via an indwelling subarachnoid catheter. Blood was withdrawn every 10 min via an antecubital vein catheter. Fed subjects received a meal at 1:00 PM. Subjects who were fed had lower post-prandial ratings on hunger scales and higher ratings on satiety scales. Fed subjects also had slightly lower levels of CSF CRH after feeding. Furthermore, fed subjects had higher ACTH and cortisol concentrations in the first 3 h; by the fourth h the opposite was true. Our findings do not support the hypothesis that CNS CRH is a central satiety factor in the human. Instead our findings of slightly diminished CSF CRH levels after feeding may be accounted for by the rises in glucocorticoids and their associated negative feedback effects on CNS CRH. Alternatively, our findings could also reflect changes in CRH levels associated with feeding in multiple brain areas and in the spinal cord with the net effect being in the negative direction.

Serum thyrotropin concentrations and bioactivity during sleep deprivation in depression

BACKGROUND

One night of sleep deprivation induces a brief remission in about half of depressed patients. Subclinical hypothyroidism may be associated with depression, and changes in hypothalamic-pituitary-thyroid function may affect the mood response to sleep deprivation. We wished to define precisely the status of the hypothalamic-pituitary-thyroid axis of depressed patients during sleep deprivation and the possible relationship of hypothalamic-pituitary-thyroid function to the mood response.

METHODS

We studied 18 patients with major depressive disorder and 10 normal volunteers. We assessed mood before and after sleep. We measured serum thyrotropin every 15 minutes during the night of sleep deprivation, thyrotropin bioactivity, the thyrotropin response to protirelin the next afternoon, and other indexes of hypothalamic-pituitary-thyroid function. To determine if the changes were limited to the hypothalamic-pituitary-thyroid axis, we measured serum cortisol, which also has a circadian secretory pattern.

RESULTS

Nocturnal serum thyrotropin concentrations were consistently higher in responders, entirely because of elevated levels in the women reponders. Responders had exaggerated responses to protirelin the next afternoon. The bioactivity of thyrotropin in nonresponders was significantly greater than in responders (F(1,8. 99) = 7.52; P =.02). Other thyroid indexes and serum cortisol concentrations were similar among groups.

CONCLUSIONS

Depressed patients have mild compensated thyroid resistance to thyrotropin action, not subclinical autoimmune primary hypothyroidism. Sleep deprivation responders compensate by secreting more thyrotropin with normal bioactivity; nonresponders compensate by secreting thyrotropin with increased bioactivity.

Intra- and inter-individual correlations between cholecystokinin and corticotropin-releasing hormone concentrations in human cerebrospinal fluid

Despite strong evidence of a physiologic relationship between cholecystokinin (CCK) and corticotropin-releasing hormone (CRH) in the rat central nervous system (CNS), evidence of such a relationship between the two hormones in the human CNS is lacking. A post hoc analysis of serial concentrations of immunoreactive CCK and CRH, obtained every ten minutes from CSF continuously collected over six hours, was performed. A total of 30 subjects were studied: 15 normal volunteers, 10 patients with major depression, and 5 recently-abstinent, alcohol-dependent patients. Overall, we observed an average intra-subject correlation of +.273 (P < 0.001) between CSF CRH and CCK. Inter-subject correlations between mean CSF levels of CRH and CCK were +.948 (P = 0.0001) and +.959 (P = 0.005) in the depressed and abstinent alcoholic patients, respectively. These inter-individual correlations were significantly greater than that seen within the group of normal volunteers (r = +.318, n.s.). The present data suggest that interactions between CCK and CRH are significant in the human CNS, particularly perhaps in depressed and alcoholic patients, and that CSF samples may be used to assess elements of the relationship between these hormones.

Serial CSF corticotropin-releasing hormone levels and adrenocortical activity in combat veterans with posttraumatic stress disorder

OBJECTIVE

The authors sought to carefully test, by using a technique of continuous CSF sampling, the hypothesis that basal elevations in CSF corticotropin-releasing hormone (CRH) concentrations exist in patients with posttraumatic stress disorder (PTSD). They also sought to assess the relationship among PTSD symptoms, adrenocortical activity, and CSF CRH levels.

METHOD

CSF was withdrawn by means of a flexible, indwelling subarachnoid catheter over a 6-hour period, and hourly CSF concentrations of CRH were determined for 11 well-characterized combat veterans with PTSD and 12 matched normal volunteers. Twenty-four-hour urinary-free cortisol excretion was also determined. PTSD and depressive symptoms were correlated with the neuroendocrine data.

RESULTS

Mean CSF CRH levels were significantly greater in PTSD patients than in normal subjects (55.2 [SD = 16.4] versus 42.3 pg/ml [SD = 15.6]). No correlation was found between CSF CRH concentrations and PTSD symptoms. While there was no significant difference between groups in 24-hour urinary-free cortisol excretion, the correlation between 24-hour urinary-free cortisol excretion and PTSD symptoms was negative and significant.

CONCLUSIONS

By using a serial CSF sampling technique, the authors found high basal CSF CRH concentrations and normal 24-hour urinary-free cortisol excretion in combat veterans with PTSD, a combination that appears to be unique among psychiatric conditions studied to date.

Cerebrospinal fluid and plasma beta-endorphin in combat veterans with post-traumatic stress disorder

Opioid-mediated analgesia develops in experimental animals following traumatic stress and increased opioid-mediated analgesia has been observed in combat veterans with post-traumatic stress disorder (PTSD). These observations have led to the hypothesis that increased central nervous system (CNS) opioidergic activity exists in patients with PTSD. However, direct CNS data on opioid peptide concentrations and dynamics in patients with PTSD are lacking. We withdrew cerebrospinal fluid (CSF) via a flexible, indwelling subarachnoid catheter over a 6-h period and determined hourly CSF concentrations of immunoreactive beta-endorphin (ir beta END) in 10 well-characterized combat veterans with PTSD and nine matched normal volunteers. Blood was simultaneously withdrawn to obtain plasma for ir beta END. PTSD symptom clusters, as measured by the CAPS, were correlated with neuroendocrine data. Mean CSF ir beta END was significantly greater in patients with PTSD compared with normals and there was a negative correlation between the ir beta END and PTSD intrusive and avoidant symptoms of PTSD. No intergroup difference between plasma ir beta END was found, nor was there a significant correlation between CSF and plasma ir beta END. Immunoreactive beta-lipotropin (ir beta LPH) and pro-opiomelanocortin (irPOMC), both precursors of beta END, were much more plentiful in human CSF than was beta-endorphin itself, as has been previously reported. It remains to be determined whether the increased CNS opioid concentrations predate traumatic stress, thereby conferring a vulnerability to dissociative states and PTSD itself, or result from the trauma. The negative correlation between CSF ir beta END and avoidant and intrusive symptoms suggests that CNS hypersecretion of opioids might constitute an adaptive response to traumatic experience. Poor correlation between CSF and plasma ir beta END limits use of plasma measures to assess CNS opioid activity.

Low cerebrospinal fluid corticotropin-releasing hormone concentrations in eucortisolemic depression

Hypersecretion of corticotropin-releasing hormone (CRH) and resulting hypercortisolism have been implicated in the pathogenesis of major depression. To test this CRH hypersecretion hypothesis, cerebrospinal fluid (CSF) was continuously withdrawn from 11:00 AM to 5:00 PM via an indwelling subarachnoid catheter (placed at 8:00 AM), and immunoreactive CRH concentrations were determined at 10-min intervals in 10 depressed patients, the majority of whom exhibited at least one "atypical" symptom, and in 15 normal volunteers. CSF CRH was low, plasma adrenocorticotropin (ACTH) tended to be low, and plasma cortisol was normal in the depressed patients. Also, tobacco smokers had lower CSF CRH than nonsmokers. CRH increased acutely in response to lumbar puncture, had a brief half-life, showed rapid variability in concentration over time, and displayed a diurnal concentration rhythm that was preserved in fasting individuals and in most depressed patients. CSF CRH did not correlate with plasma ACTH or cortisol; this and its rapidly fluctuating levels suggest a primarily extrahypothalamic origin of lumbar CSF CRH.

Plasma corticotropin and cortisol responses to ovine corticotropin-releasing hormone (CRH), arginine vasopressin (AVP), CRH plus AVP, and CRH plus metyrapone in patients with Cushing's disease

The CRH test may sometimes be useful in the differential diagnosis of Cushing's syndrome, because most patients with pituitary ACTH-dependent Cushing's syndrome (Cushing's disease) respond to CRH, but those with other causes of Cushing's syndrome usually do not. However, about 10% of Cushing's disease patients fail to respond to CRH. We wondered if we could eliminate these false negative results either by exploiting the potential additive or synergistic effects of another ACTH secretagogue or by reducing glucocorticoid inhibition of CRH's ACTH-releasing effect. We compared the effect on plasma ACTH and cortisol in 51 patients with Cushing's disease of administering ovine CRH (1 microgram/kg BW, i.v.) alone, arginine vasopressin (AVP; 10 U, i.m.) alone, the combination of CRH and AVP, and CRH after pretreatment with metyrapone (1 g, orally, every 4 h for three doses; CRH + MET). The rates of nonresponse (ACTH increment, < 35%; cortisol increment, < 20%) to AVP and CRH alone were 26% and 8%, respectively; all patients responded to CRH + AVP. The lack of response was not due to improper administration or rapid metabolism of the agonist, because plasma CRH and AVP concentrations were similar in responders and nonresponders. A synergistic ACTH response to CRH + AVP occurred in 65% of the patients. MET pretreatment increased basal plasma ACTH levels in most patients and induced the greatest mean peak ACTH response to CRH, but 8% of the patients did not respond to CRH + MET with an ACTH increment of 35% or more. Because all of the Cushing's disease patients tested in this study responded to the combination of CRH + AVP, whereas 8% failed to respond to CRH alone, we conclude that CRH + AVP administration may provide a more reliable test for the differential diagnosis of ACTH-dependent Cushing's syndrome than administration of CRH alone. Whether this improved sensitivity is accompanied by unaltered specificity for Cushing's disease must be tested in patients with chronic ectopic ACTH syndrome.

Individual differences in repressive-defensiveness predict basal salivary cortisol levels

Prior studies assessing the relation between negative affective traits and cortisol have yielded inconsistent results. Two studies assessed the relation between individual differences in repressive-defensiveness and basal salivary cortisol levels. Experiment 1 assessed midafternoon salivary cortisol levels in men classified as repressors, high-anxious, or low-anxious. In Experiment 2, more rigorous controls were applied as salivary cortisol levels in women and men were assessed at 3 times of day on 3 separate days. In both studies, as hypothesized, repressors and high-anxious participants demonstrated higher basal cortisol levels than low-anxious participants. These findings suggest that both heightened distress and the inhibition of distress may be independently linked to relative elevations in cortisol. Also discussed is the possible mediational role of individual differences in responsivity to, or mobilization for, uncertainty or change.

Preprothyrotropin-releasing hormone-(178-199) does not inhibit corticotropin release

Pituitary ACTH synthesis and secretion are positively regulated by hypothalamic factors and negatively regulated by adrenal corticosteroids. Negative hypothalamic regulation of pituitary ACTH synthesis and secretion has been postulated, but not proved. The search for a hypothalamic corticotropin release-inhibiting factor has recently focused on peptides derived from the prepro-TRH precursor of TRH. One of the peptides, prepro-TRH-(178-199), was reported to suppress basal and stimulated ACTH release. We examined the effects of prepro-TRH-(178-199) alone and in combination with CRH and corticosterone, two known physiologic regulators of ACTH secretion. Prepro-TRH-(178-199) had no effect on basal, stimulated, or attenuated ACTH release from cells that responded normally to CRH and/or corticosterone. These results indicate that prepro-TRH-(178-199) is not a corticotropin release-inhibiting factor.

Individual differences in repressive-defensiveness predict basal salivary cortisol levels

Prior studies assessing the relation between negative affective traits and cortisol have yielded inconsistent results. Two studies assessed the relation between individual differences in repressive-defensiveness and basal salivary cortisol levels. Experiment 1 assessed midafternoon salivary cortisol levels in men classified as repressors, high-anxious, or low-anxious. In Experiment 2, more rigorous controls were applied as salivary cortisol levels in women and men were assessed at 3 times of day on 3 separate days. In both studies, as hypothesized, repressors and high-anxious participants demonstrated higher basal cortisol levels than low-anxious participants. These findings suggest that both heightened distress and the inhibition of distress may be independently linked to relative elevations in cortisol. Also discussed is the possible mediational role of individual differences in responsivity to, or mobilization for, uncertainty or change.

Role of inositol trisphosphate-sensitive calcium stores in the regulation of adrenocorticotropin secretion by perifused rat anterior pituitary cells

Intracellular Ca2+ (Cai2+) stores contribute significantly to Ca2+ signaling in many types of cells. We studied the role of inositol trisphosphate (InsP3)-sensitive Ca2+ stores, a principal Cai2+ store that presumably is within the endoplasmic reticulum (ER), in cell signaling by examining the effect of thapsigargin (Tg), an ER Ca2+ pump inhibitor that depletes the ER Ca2+ pool, on ACTH secretion. Preincubation for 6-24 h with 2-20 nM Tg had no effect on the resting cytosolic free Ca2+ concentrations ([Cai2+]) but inhibited the ionomycin-stimulated spike-type increase in [Cai2+], which is mediated by InsP3-independent Cai2+ release from the ER, in a dose-dependent (IC50, 4 nM) and time-dependent manner. In ER Cai(2+)-depleted cells, the spike phase (initial 5 min) of the ACTH secretory response to arginine vasopressin (AVP), which is mediated by InsP3-induced Cai2+ release, was also attenuated (IC50, 7.3 nM). However, the spike phase of the ACTH secretory response to AVP was inhibited to a much greater degree than the spike-type response to ionomycin, suggesting that ER Cai2+ stores might have functions other than simply providing Ca2+ for InsP3-stimulated Cai2+ release. Tg pretreatment (IC50, 12 nM) also markedly inhibited the sustained plateau (final 15-min) phase of the ACTH secretory response to AVP, which is mediated by diacylglycerol-induced activation of protein kinase C and subsequent influx of extracellular Ca2+ via L-type voltage-sensitive Ca2+ channels (VSCC), but had no effect on the sustained (full 20 min) response to dioctanoylglycerol that directly activates protein kinase C. Tg had no effect on specific cell binding of [125I]AVP or on specific cell binding of [3H]phorbol 12,13-dibutyrate (except at 20 nM Tg), an index of protein kinase C concentration, or on protein kinase C activity. AVP significantly stimulated inositol trisphosphate accumulation, but pretreatment with Tg completely abolished this effect of AVP, whereas [3H]myoinositol incorporation into membrane-associated inositol lipids and inositol phosphates was unaffected. Thus, Tg-induced depletion of ER Cai2+ stores inhibited both the spike and plateau phases of the ACTH secretory response to AVP, presumably by inhibiting phospholipase C activity and the resulting generation of InsP3 and diacylglycerol. Preincubation with Tg inhibited, in a dose-dependent (IC50, 13 nM) and time-dependent manner, the sustained ACTH secretory response to corticotropin-releasing hormone (CRH) that is mediated by cAMP-induced activation of protein kinase A and Cae2+ influx via L-type VSCC, and the sustained response to forskolin, which directly activates adenylate cyclase.(ABSTRACT TRUNCATED AT 400 WORDS)

Glucocorticoid receptor structure and function in an adrenocorticotropin-secreting small cell lung cancer

ACTH secretion by tumors of nonpituitary origin is characteristically resistant to negative feedback regulation by glucocorticoids. One possible mechanism for the phenomenon could be a structural defect in the intracellular glucocorticoid receptor (GR). We studied the GR in DMS-79 cells derived from a human ACTH-secreting small cell lung cancer. Compared with control cells, DMS-79 cells were found to have greatly diminished GR ligand-binding activity and immunoreactive 94-kilodalton (kDa) GR content. Northern blot analysis revealed expression of GR transcripts that appeared to be slightly larger than those in control cells. A DMS-79 cell GR cDNA was cloned by reverse transcription/polymerase chain reaction amplification of mRNA using primers specific for full-length normal GR. The derived sequence of this full-length GR differed from the reported sequence by a single altered codon (G to A; Asn to Ser at codon 363) outside the steroid-binding domain. This N363S DMS-79 GR functioned normally to activate a target gene [mouse mammary tumor virus-chloramphenicol acetyl transferase (MMTV-CAT)] in transient transfection experiments in COS cells. Evidence for expression of a second type of GR mRNA was obtained by screening a DMS-79 cell cDNA library. This GR cDNA contained normal GR sequence up to nucleotide 2155, corresponding exactly to the end of exon 7 in the normal GR gene. The sequence appended to the GR sequences was not matched by any known sequence in DNA databases and included an in-frame termination codon after only 6 bases. The predicted truncated GR protein product (GR delta) has a mol wt of 73,740 and lacks most of the ligand-binding domain. Transient transfection of the GR delta form into COS cells did not reveal any dominant negative effect on the function of a cotransfected normal GR.(ABSTRACT TRUNCATED AT 250 WORDS)

Cushing's syndrome

Cushing's syndrome is usually caused by the secretion of corticotropin or cortisol by a pituitary or adrenal tumor, respectively, or by ectopic secretion of corticotropin. It is possible to determine the specific abnormality in most patients, but it can sometimes be difficult to decide whether the patient has hypercortisolism and whether it is primary or due to major depressive disorder or to the stress of other diseases. Determining the cause of the hypercortisolism involves performing multiple tests in a logical sequence; the results should all be consistent with the same diagnosis. Treatment should aim to cure the hypercortisolism and to eliminate any tumor that threatens the patient's health, while minimizing the chance of an endocrine deficiency or long-term dependence on medications.

Concentrations of corticotropin-releasing hormone, norepinephrine, MHPG, 5-hydroxyindoleacetic acid, and tryptophan in the cerebrospinal fluid of alcoholic patients: serial sampling studies

Abnormalities in corticotropin-releasing hormone (CRH) secretion, noradrenergic neurotransmission, and serotonergic activity in the central nervous system (CNS) have all been hypothesized to exist in alcoholic patients, as have abnormalities in hypothalamic-pituitary adrenal function. To test these hypotheses, we continuously sampled cerebrospinal fluid (CSF) from alcoholic patients after 38-124 days of abstinence and from normal volunteers via a flexible, indwelling lumbar subarachnoid catheter and measured CRH, norepinephrine (NE), 3-methoxy-4-hydroxyphenylglycol (MHPG), tryptophan, and 5-hydroxyindoleacetic acid (5-HIAA) concentrations at 10-min intervals, from 11:00 through 17:00 h. The spinal canal catheter was inserted at approximately 08:00 h. Serial plasma ACTH, cortisol, and NE concentrations were also measured. A mixed liquid meal was consumed at 13:00 h. CSF CRH concentrations were lower in alcoholic patients than in normal volunteers (26 +/- 15 vs. 60 +/- 30 pg/ml, respectively, p < 0.05 by ANOVA), as were CSF NE levels (0.33 +/- 0.09 vs. 1.15 +/- 0.51 pmol/ml, respectively, p < 0.01). Plasma NE and CSF MHPG levels were normal in the alcoholic patients. CSF tryptophan and 5-HIAA and plasma ACTH and cortisol concentrations did not differ between the groups. These studies extend our finding of reduced spinal canal CSF CRH concentrations in depressed patients to abstinent chronic alcoholics.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of lipoxygenase metabolites of arachidonic acid in the regulation of adrenocorticotropin secretion by perifused rat anterior pituitary cells

Arachidonic acid metabolites have been implicated in the regulation of ACTH secretion. To define further which eicosanoid(s) is primarily involved, we examined the effects of both inhibitors of the three arachidonate metabolic pathways (cyclooxygenase, lipoxygenase, and epoxygenase) and specific eicosanoid products on ACTH secretion by rat pituitary corticotrophs in a microperifusion system. CRF stimulates sustained ACTH release that is mediated by protein kinase-A-induced extracellular Ca2+ (Cae2+) influx via L-type voltage-sensitive calcium channels (VSCC). Arginine vasopressin (AVP) stimulates an initial spike phase of ACTH release that presumably is mediated by inositol 1,4,5-trisphosphate-induced intracellular Ca2+ (Cai2+) release, followed by a sustained plateau phase of ACTH release that is mediated by protein kinase-C-induced Cae2+ influx via L-type VSCC. Pretreatment for 15 min with the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA; 50 microM), but not the cyclooxygenase inhibitor indomethacin (10 microM) or the epoxygenase inhibitor SKF525A (100 microM) inhibited the sustained response to CRF by 48% and the initial spike response to AVP by 38%. NDGA-induced inhibition was not reversed by indomethacin or SKF525A, alone or in combination, precluding arachidonate shunting into other pathways. However, the results suggested that epoxygenase metabolites may have a minor stimulatory and cyclooxygenase metabolites may have a minor inhibitory effect on ACTH secretion. Preexposure to NDGA suppressed by 43% the sustained response to 8-bromo-cAMP, which directly activates protein kinase-A; by 57% the sustained response to dioctanolglycerol, which directly activates protein kinase-C; and by 59% the spike-type response to ionomycin, which releases Cai2+ by an inositol 1,4,5-trisphosphate-independent mechanism. These results suggest that NDGA either inhibits the production of a lipoxygenase metabolite involved in Cae2+ influx and/or Cai2+ release or acts other than by inhibiting lipoxygenase, such as by directly blocking membrane transport of Cae2+. The three major lipoxygenase metabolites tested, 5(S)-, 12(S)-, and 15(S)-hydroxyeicosatetraenoic acid (HETE), all stimulated sustained ACTH release in a dose-dependent manner. At a concentration of 2 microM, 12(S)-HETE was 4.7 and 2.5 times more potent than 5(S)- and 15(S)-HETE, respectively, and completely reversed NDGA inhibition of both CRF- and AVP-stimulated ACTH secretion. The ACTH-releasing activity of 12(S)-HETE was inhibited 26% by removing Cae2+ and 54% by both removing Cae2+ and depleting Cai2+, indicating either that 12(S)-HETE facilitates transmembrane Ca2+ transfer or that increased cytosolic Ca2+ is necessary for 12(S)-HETE's action.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocortical dysplasia: a mouse model system for adrenocortical insufficiency

A spontaneous autosomal recessive mutation causing disordered morphogenesis of the adrenal cortex has been identified in DW/J inbred strain mice and named adrenocortical dysplasia (acd). The acd mutant gene has been mapped just proximal to oligosyndactyly (Os) and esterase-1 (Es-1) in the central region of chromosome 8. Both male and female acd/acd mice are characterized by reduced survival, retarded growth, skin hyperpigmentation, poorly developed pelage and focal ureteral blockage leading to hydronephrosis. Morphometric measurements showed that acd/acd cortical cells and nuclei were increased sevenfold in volume; nuclei often showed a variety of inclusions. Cortical cells of acd/acd mice contained large numbers of mitochondria, smooth endoplasmic reticulum and lipid droplets characteristic of steroidogenic cells. While cortical X-zones failed to develop in acd/acd adrenals, medullary cells and nuclei were unaffected by mutant gene action. Resting serum corticosterone levels in female, but not male, mutant mice were significantly lower than in +/? normal littermates, whereas ACTH levels were significantly elevated in mutants of both sexes. Serum aldosterone levels were normal in acd/acd mice. Functional studies of adrenals cultured in vitro revealed that acd/acd adrenals secreted reduced amounts of corticosterone per pair of glands under both basal and ACTH-stimulated conditions. However, correction of the corticosterone secretion data to mg cortical mass in culture showed that the mutant cortical tissue secreted the same amount of glucocorticoid as did their +/? normal littermate glands. We conclude that the acd mutant gene acts in an unknown fashion to cause a fundamental defect in cellular proliferation in the adrenal cortex, leading to compensatory marked hypertrophy of cortical cells and grossly enlarged nuclei. The role of acd action in adrenal cortical development remains to be established.

Plasma concentrations of immunoreactive proopiomelanocortin peptides and cortisol in clinically normal cats

We measured immunoreactive (IR) plasma concentrations of the proopiomelanocortin (POMC)-derived peptides (adrenocorticotropic hormone [ACTH]; beta-endorphin/beta-lipotropin [beta END/beta LPH]; and alpha-melanocyte stimulating hormone [alpha MSH]) and of cortisol in 100 clinically normal cats. Median plasma concentration of IR-ACTH was 2.7 pmol/L (range, < or = 1.1 to 22 pmol/L), of beta END/beta LPH was 28 pmol/L (range, 3.8 to 130 pmol/L), of alpha MSH was 36 pmol/L (range, < or = 3.6 to 200 pmol/L), and of cortisol was 35 nmol/L (range, 5 to 140 nmol/L). Plasma concentrations of IR-ACTH, alpha MSH, and beta END/beta LPH were at or below the assay sensitivity in 34, 3, and 0% of the cats, respectively. We did not detect a correlation between plasma concentrations of IR-ACTH and beta END/beta LPH (r = 0.23) or between plasma concentrations of IR-ACTH and alpha MSH (r = 0.19). However, there was a significant (P < 0.001) correlation between plasma concentrations of IR-beta END/beta LPH and alpha MSH (r = 0.81). There was not a significant correlation between plasma concentration of cortisol and plasma concentration of any of the IR-POMC peptides. High plasma concentrations of IR-alpha MSH and beta END, POMC peptides secreted predominantly by melanotrophs in other species, indicate that clinically normal cats have an actively secreting pars intermedia.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholecystokinin in human cerebrospinal fluid: concentrations, dynamics, molecular forms and relationship to fasting and feeding in health, depression and alcoholism

Very little is known about the physiologic significance of the gut-brain hormone cholecystokinin (CCK) in the human central nervous system, although the hormone has been hypothesized to be involved in the regulation of both appetite and anxiety. We continuously collected lumbar cerebrospinal fluid (CSF) via indwelling subarachnoid catheters in ten normal volunteers, ten patients with major depression and five abstinent alcoholic humans, while fasting and after eating. Five other healthy subjects were fasted throughout the experiment. We quantified CSF immunoreactive cholecystokinin (IR-CCK) and glucose concentrations at 10-min intervals from 11.00 to 17.00 h. No difference in CSF IR-CCK concentration, half-life or rhythm was observed between normal volunteers and either depressed or alcoholic patients. Fasting CSF IR-CCK concentrations were 1.3 +/- 0.18, 1.3 +/- 0.21 and 1.2 +/- 0.21 fmol/ml (mean +/- S.E.M.) in normal volunteers, depressed patients and alcoholic patients, respectively. After eating, CSF IR-CCK concentrations rose to 1.5 +/- 0.21, 1.5 +/- 0.24 and 1.4 +/- 0.26 fmol/ml, respectively. Normal volunteers who did not eat had similar basal CSF IR-CCK concentrations (1.1 +/- 0.1 fmol/ml) which similarly rose to 1.4 +/- 0.13 fmol/ml during the sampling interval. In contrast, CSF glucose concentrations rose only in the subjects who ate, beginning to rise after about 1 h and remaining elevated for at least 3 h after eating. These data suggest the existence of a diurnal rhythm of IR-CCK release into CSF, as opposed to a response to feeding. The disappearance half-time of CCK in human CSF is less than 13 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid and adrenal dysfunction in abstinent alcoholic men: locus of disturbance

Certain neuroendocrine abnormalities (e.g., blunted plasma adrenocorticotropic hormone [ACTH] response to corticotropin-releasing hormone [CRH] administration and blunted serum TSH response to thyrotropin-releasing hormone [TRH] administration) are common in alcoholic patients. It was the objective of this study to evaluate whether they are centrally mediated: that is, whether they are secondary to increased activity of CRH and/or TRH neurons. We evaluated the nocturnal secretion (2200 hours to 1000 hours, q 15 min) of plasma ACTH, serum cortisol, and serum TSH, and their responses to the combined administration of CRH and TRH, in 28 acutely abstinent alcoholic (age range: 32 to 57 years; mean: 42.4 years) and 19 normal men (age range: 21 to 52 years; mean: 32.1 years). To assess the validity of administering CRH and TRH simultaneously, we gave 10 additional abstinent alcoholic men (age range: 36 to 53 years; mean: 45.8 years), in random order and at least 4 days apart, either CRH, TRH, placebo, or CRH plus TRH. Nocturnal ACTH, cortisol, and TSH secretion, as well as cortisol and TSH responses after CRH plus TRH administration, were similar in alcoholic and normal men. However, ACTH peak responses to CRH plus TRH were reduced in the alcoholic men (p < 0.05). The ACTH, but not cortisol, response was greater after combined CRH plus TRH administration than after CRH alone (p < .002). The blunted ACTH response does not appear to be the result of increased endogenous CRH activity, because all parameters of nocturnal ACTH pulsatility were normal in the alcoholics. It rather appears to be secondary to an intrinsic defect in the CRH responsiveness of the pituitary corticotroph, possibly due to genetic vulnerability or to the toxic effects of prolonged alcohol abuse.

Effect of protein kinase-C depletion on inositol trisphosphate-mediated and cyclic adenosine 3',5'-monophosphate-dependent protein kinase-mediated adrenocorticotropin secretion

We studied the effect of Ca2+/phospholipid-dependent protein kinase-C (protein kinase-C) down-regulation by chronic exposure to phorbol 12-myristate 13-acetate (PMA) on ACTH secretion by dispersed male rat anterior pituitary cells in a microperifusion system. Preincubation for 24 h and preperifusion for 3 h with 0.1 and 1 microM PMA significantly inhibited (by 85% and 91%, respectively) the specific cell binding of [3H]phorbol 12,13-dibutyrate, an index of protein kinase-C concentration, and significantly reduced (by 101% and 20%, respectively) the sustained plateau (final 15-min) phase of the ACTH response to arginine vasopressin (AVP) and (by 56% and 54%, respectively) the sustained (full 20-min) response to dioctanoylglycerol (DOG), both of which are mediated by protein kinase-C activation. In contrast, the spike (initial 5-min) phase of the response to AVP, which is mediated by intracellular Ca2+ release from inositol 1,4,5-trisphosphate (InsP3)-sensitive stores, was significantly increased (by 112% and 99%, respectively), but the spike-type response to ionomycin, which releases intracellular Ca2+ by an InsP3-independent mechanism, was unaffected. AVP significantly stimulated inositol bisphosphate and InsP3, but not inositol monophosphate, accumulation, and PMA pretreatment significantly enhanced their AVP-stimulated accumulation (by 86%, 34%, and 78%, respectively), an effect that was abolished by simultaneous preperifusion with PMA and cycloheximide to inhibit new protein synthesis. Enhancement of the spike phase response to AVP and AVP-stimulated InsP3 accumulation were lost within 1 h of PMA removal, but [3H]phorbol 12,13-dibutyrate binding and the sustained responses to AVP and DOG remained suppressed after 3 h. Pretreatment with 0.1 and 1 microM PMA slightly reduced the sustained responses to CRF (by 29% and 16%, respectively) and 8-bromo-cAMP (by 8% and 12%, respectively), which are mediated by protein kinase-A activation and extracellular Ca2+ influx via L-type voltage-sensitive Ca2+ channels, but not the response to KCl, which is mediated by extracellular Ca2+ influx via all types of voltage-sensitive Ca2+ channels. The sustained response to CRF was still suppressed 1 h after PMA removal, but returned to the control level by 3 h. When new protein synthesis was inhibited by preperifusion with cycloheximide alone for 3 h after 24-h PMA pretreatment, recovery from the effects of PMA was abolished. Three-hour exposure to cycloheximide without PMA pretreatment inhibited the sustained responses to CRF, AVP, and DOG, but not the spite response to AVP.(ABSTRACT TRUNCATED AT 400 WORDS)

Two patients with Cushing's disease in a kindred with multiple endocrine neoplasia type I

Cushing's disease (pituitary ACTH-dependent Cushing's syndrome) has been described in association with the syndrome of multiple endocrine neoplasia type I (MEN-I). Cushing's disease is uncommon in MEN-I and has not been reported in more than one member of a kindred. Here we describe a mother and her daughter with Cushing's disease and major depressive disorder. The mother, her other daughter, and two other relatives also had primary hyperparathyroidism. We believe this to be the first reported instance of hereditary Cushing's disease as a manifestation of MEN-I.

Chromogranin A does not mediate glucocorticoid inhibition of adrenocorticotropin secretion

It has recently been proposed that chromogranin A (CgA), a 50-kilodalton acidic glycoprotein that is costored and cosecreted with hormones and neurotransmitters in a variety of tissues, mediates glucocorticoid inhibition of ACTH secretion from AtT20/D16v mouse anterior pituitary corticotroph tumor cells by an undefined autocrine mechanism. We used AtT20/D16v cells, RIAs for murine CgA and ACTH, complementary DNA probes for CgA and POMC, the precursor of ACTH, antiserum that reacts with murine CgA, highly purified bovine CgA, and synthetic rat and porcine pancreastatin, a bioactive cleavage product of CgA in some systems, to study the kinetics of the effect of glucocorticoids on CgA and ACTH synthesis and secretion and of CgA's subsequent effects on ACTH secretion. Exposure to 100 nM dexamethasone (DEX) did not alter the size of CgA or POMC messenger RNA (mRNA) transcripts but increased cell CgA mRNA content 42% by 3 h and 192% by 48 h. DEX decreased cell POMC mRNA content 22% by 6 h and 57% by 48 h. These divergent effects of DEX on steady state mRNA levels were accompanied by similar divergent effects on the production of CgA and ACTH protein. Thirty-minute exposure to 10 nM ovine CRF increased CgA and ACTH release to 300% and 360% of basal levels, respectively. One-hour DEX pretreatment inhibited CRF-stimulated CgA and ACTH release 58% and 49% at 30 min and 67% and 66% at 60 min, respectively. There was a positive correlation between CgA and ACTH release under all conditions at both times (r = 0.976 and 0.964, respectively, P < 0.001), consistent with costorage and cosecretion of the two proteins. The ratio of secreted ACTH to CgA decreased progressively with DEX treatment. Purified bovine CgA (100 nM) had little or no effect on basal or CRF-stimulated ACTH secretion from AtT20/D16v cells, 100 nM synthetic pancreastatin had no significant effect on basal or CRF-stimulated ACTH release from AtT20/D16v cells or dispersed normal male rat anterior pituitary cells, and anti-CgA sera had no significant effect on basal or CRF-stimulated ACTH release from AtT20/D16v cells. These results indicate: 1) that DEX stimulates CgA synthesis, whereas it inhibits POMC synthesis; 2) that CgA and ACTH are cosecreted; 3) that DEX increases CgA secretion relative to ACTH secretion, but decreases the absolute secretion of both proteins; and 4) that neither CgA nor its proteolytic product, pancreastatin, inhibits ACTH secretion. Thus, CgA does not mediate the inhibitory effect of DEX on ACTH secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Psychiatric phenomenology in Cushing's disease

We evaluated 20 patients with Cushing's disease (i.e., Cushing's syndrome due to ACTH-secreting pituitary microadenoma) and 20 patients with Major Depressive Disorder (MDD) using the Structured Clinical Interview for DSM-III-R (SCID) and Research Diagnostic Criteria. The diagnosis of Generalized Anxiety Disorder (GAD) was most common in Cushing's disease (79%), followed by MDD (68%), and Panic Disorder (PD) including subthreshold PD (53%). The combination of MDD and GAD and/or PD was also common in Cushing's disease (63%). Behavioral symptoms, if present, usually first occurred at or after the onset of the first physical symptoms. However, the onset of PD was associated with more chronic stages of Cushing's disease. In both Cushing's disease and MDD, more female than male relatives suffered from MDD, whereas more male than female relatives suffered from substance abuse. The data demonstrate a syndrome of anxious depression in patients with active Cushing's disease; such comorbidility has not been previously noted. The data also point to intriguing epidemiological, clinical, and biological associations between Cushing's disease, MDD and substance abuse.

Serial cerebrospinal fluid corticotropin-releasing hormone concentrations in healthy and depressed humans

CRH, a hypothalamic peptide that is the most potent ACTH secretagogue known, also appears to be produced in the cerebral cortex and spinal cord. Depressed patients have blunted responses to exogenous CRH and normal to high concentrations of CRH immunoreactivity in single morning samples of lumbar cerebrospinal fluid (CSF). Although these data suggest that depression may be associated with hypersecretion of CRH, it has also been postulated that central nervous system insufficiency of CRH might have a pathophysiological role in certain depressive syndromes. We continuously sampled lumbar CSF via indwelling subarachnoid catheters from 1100-1700 h and measured CRH at 10-min intervals in depressed patients and normal subjects. A standardized mixed liquid meal was administered at 1300 h. CSF CRH was strikingly reduced in depressed patients compared to normal subjects [4.2 +/- 1.1 pmol/L vs. 13 +/- 2.1 pmol/L (mean +/- SEM), respectively, P less than 0.01 by Wilcoxon test]. CSF CRH concentrations rose progressively during the experiment in both groups, suggesting a diurnal rhythm and, possibly, response to a test meal. CRH had a very brief half-life in CSF (less than 10 min), suggesting that the spinal cord is the origin of CRH in lumbar CSF. The rapid transients in CSF CRH concentration demonstrate that single samples provide very limited information. There were no intraindividual correlations between CSF CRH concentrations and those of either plasma ACTH or cortisol, both of which rose in response to eating. The present data show that impaired central nervous system secretion of CRH can exist during states of severe depression.

Lymphocyte-derived adrenocorticotropin is insufficient to stimulate adrenal steroidogenesis in hypophysectomized rats

Cells of the immune system can produce and respond to peptide hormones associated with the endocrine system. However, the physiological significance of these endocrine-immune interactions is not known. It has been postulated that cells of the immune system, when stimulated with viruses that induce interferon-alpha, produce sufficient levels of ACTH to stimulate adrenal steroidogenesis and, thus, function as an auxiliary source of ACTH that may have a role in the response to stress. However, we have confirmed that levels of ACTH-related peptides produced by immunocompetent cells are far lower than those produced by the pituitary, raising questions about the ability of lymphocyte-derived ACTH to stimulate adrenal function. Furthermore, we have rigorously examined this issue using intact and hypophysectomized rats treated with Newcastle disease virus. Although high levels of interferon-alpha were produced by both intact and hypophysectomized rats, and the plasma corticosterone concentration increased dramatically in intact animals, corticosterone remained undetectable in hypophysectomized rats. The lack of a corticosterone response in these animals was not due to adrenal insensitivity to ACTH, as shown by a normal rise in corticosterone following Cosyntropin injection 8 h after hypophysectomy. The findings demonstrate that levels of ACTH produced by nonpituitary sources in response to viral infection are not sufficient to stimulate adrenal steroidogenesis.

Effects of synthetic ovine corticotropin-releasing hormone on plasma concentrations of immunoreactive adrenocorticotropin, alpha-melanocyte-stimulating hormone, and cortisol in dogs with naturally acquired adrenocortical insufficiency

We evaluated the effect of ovine corticotropin-releasing hormone (CRH) on plasma immunoreactive (IR) concentrations of ACTH, alpha-melanocyte-stimulating hormone, and cortisol in 8 dogs with naturally acquired adrenocortical insufficiency. Of the 7 dogs with primary adrenal insufficiency, 6 had markedly high basal plasma IR-ACTH concentrations and exaggerated ACTH responses to CRH administration, whereas 1 dog that was receiving replacement doses of prednisone at the time of testing had normal basal IR-ACTH concentrations and a nearly normal response to CRH. In contrast, the 1 dog with secondary adrenocortical insufficiency had undetectable basal plasma IR-ACTH concentrations, which failed to increase after administration of CRH. Basal plasma alpha-melanocyte-stimulating hormone concentrations in the dogs with adrenal insufficiency were within normal range and were unaffected by CRH administration. In all 8 dogs with adrenal insufficiency, plasma cortisol concentrations were low and did not increase after administration of CRH. Therefore, stimulation with CRH produced 2 patterns of plasma IR-ACTH response when administered to dogs with naturally acquired adrenal insufficiency. Dogs with primary adrenal insufficiency had high basal plasma IR-ACTH concentrations and exaggerated responses to CRH, whereas the dog with secondary adrenal insufficiency had undetectable basal plasma concentrations of IR-ACTH that did not increase after stimulation with CRH.

Effects of short and long duration hypothyroidism and hyperthyroidism on the plasma adrenocorticotropin and corticosterone responses to ovine corticotropin-releasing hormone in rats

We report here a study of the plasma ACTH and corticosterone responses to synthetic ovine CRH (oCRH) in hypothyroid and hyperthyroid rats studied 7, 15, and 60 days after either thyroidectomy or the administration of pharmacological doses of T4. The purpose of this study was to further clarify the time-dependent effects of alterations in thyroid status on the functional integrity of the hypothalamic-pituitary-adrenal axis and to aid in the interpretation of the oCRH stimulation test in hypo- and hyperthyroid states. Our data demonstrate that hypothyroid rats have a significant reduction in the cerebrospinal fluid (CSF) levels of corticosterone and a significant decrease in adrenal weight in association with significant increases in the plasma ACTH response to oCRH. On the other hand, the corticosterone response to the ACTH released during the oCRH stimulation test was significantly reduced in hypothyroidism. With increasing duration of thyroidectomy-induced hypothyroidism, there was a progressive fall in CSF corticosterone levels, a progressive increase in the plasma ACTH response to oCRH, and a gradual normalization of the corticosterone responses to the ACTH released during oCRH stimulation. Our findings in hyperthyroid rats were generally the converse of those seen in hypothyroidism. Hence, there was a significant increase in the CSF levels of corticosterone and a significant increase in adrenal weight in association with an initial slight decrease in the ACTH response to oCRH. On the other hand, the corticosterone response to the ACTH released during oCRH stimulation was significantly increased. There was a gradual increase in the magnitude of the rise in CSF corticosterone levels with time, as well as a gradual normalization of adrenocortical responses during oCRH stimulation. The ACTH plasma clearance rates were similar in hypo-, hyper-, and euthyroid rats. Our data do not permit definitive identification of the precise locus in the hypothalamic-pituitary-adrenal axis that is principally affected by experimentally induced alterations in thyroid status. However, these data are most compatible with a subtle hypothyroid-induced centrally mediated adrenal insufficiency and a subtle hyperthyroid-induced centrally mediated hypercortisolism. These data also suggest that alterations in hypothalamic-pituitary-adrenal function in states of disturbed thyroid function become somewhat more pronounced as the duration of thyroid dysfunction increases. The fact that pituitary-adrenal responses to oCRH are consistently altered in states of thyroid dysfunction may be relevant to the clinical interpretation of oCRH stimulation tests.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of intracellular Ca2+ depletion and glucocorticoid on stimulated adrenocorticotropin release by rat anterior pituitary cells in a microperifusion system

Arginine vasopressin (AVP), oxytocin (OT), and angiotensin-II (AII) elicit a biphasic ACTH secretory response by perifused anterior pituitary cells consisting of an initial transient (less than 3-min) spike phase and a subsequent sustained plateau phase. In contrast, CRF produces a monophasic sustained plateau type of ACTH secretory response. We have previously demonstrated that 1) influx of extracellular Ca2+ (Cae2+) via L-type voltage-sensitive Ca2+ channels is involved in both the response to CRF and the sustained phase of the response to AVP and OT; 2) release of intracellular Ca2+ (Cai2+) is involved in the spike phase of the response to AVP, OT, and AII; and 3) activation of protein kinase-C is required for the sustained phase, but not for the spike phase, of the response to AVP. CRF action is mediated by activation of protein kinase-A. In this study we further examined the role of Cai2+ by exploiting the fact that a low concentration (1 microM) of ionomycin, a potent Ca2+ ionophore, releases Cai2+ from nonmitochondrial inositol-1,4,5-trisphosphate (IP3)-sensitive Cai2+ stores without causing Cae2+ influx. Pretreatment with ionomycin for 10 min decreased the spike phase of the response to 100 nM AVP, OT, and AII, but had no effect on the response to 10 nM CRF or the sustained phase of the responses to the other agonists. The combination of CRF plus AVP induced a biphasic and synergistic release of ACTH. Ionomycin pretreatment reduced the spike phase, especially the first 1 min, without any effect on the sustained phase. These results indicate that Cai2+ release, but not Cae2+ influx, is involved in the spike phase of the response to AVP, OT, and AII and that Cai2+ is not involved in the synergistic effect of the combination of CRF plus AVP. Having established these relationships, we examined the effect of 2-h perifusion with 100 nM dexamethasone (DEX) on stimulated ACTH release. DEX pretreatment reduced the total response to CRF, the sustained phase of the responses to AVP and OT, and the sustained phase of the synergistic response to CRF plus AVP. However, DEX had no effect on the spike phase of the responses to AVP, OT, or AII or the spike phase of the response to CRF plus AVP. These results indicate that DEX inhibits ACTH release mediated by activation of either protein kinase-A or protein kinase-C, but does not affect inositol-1,4,5-trisphosphate/Cai2(+)-mediated ACTH release.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal function in abstinent alcoholic men

1. The nocturnal secretion of plasma ACTH and serum cortisol and their responses to ovine corticotropin-releasing hormone (oCRH) were studied in acutely abstinent alcoholic and normal men. 2. Nocturnal cortisol secretion was similar in alcoholic and normal men, but nocturnal ACTH secretion tended to be decreased during the early morning hours (0600h-0900h) in alcoholic men. ACTH, but not cortisol, responses after oCRH administration tended to be attenuated in alcoholic men. CLUSTER ANALYSIS showed that the changes were not due to alterations in ACTH pulse frequency, amplitude, or interpulse interval. 3. The data suggest an intrinsic defect in response to CRH by the pituitary corticotroph cell, possibly due to genetic vulnerability or to the toxic effects of prolonged alcohol abuse.

Distinct classes of corticotropes mediate corticotropin-releasing hormone- and arginine vasopressin-stimulated adrenocorticotropin release

ACTH release from the anterior pituitary gland is principally driven by the two hypothalamic hormones, corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP). Using the reverse hemolytic plaque assay, we have compared the effects of CRH and AVP on ACTH release from individual, dispersed pituitary cells. A small percent (0.36 +/- 0.06%) of pituitary cells formed plaques when exposed to medium alone. AVP caused 3.44 +/- 0.10% of cells to form plaques (P less than 0.01 compared with medium alone), CRH produced 4.85 +/- 0.20% plaque-forming cells (P less than 0.01 compared with AVP), and the combination of CRH and AVP produced a still greater percent of plaque-forming cells (5.80 +/- 0.20%, P less than 0.01 compared with CRH alone). A double reverse hemolytic plaque assay was then employed to examine whether some cells formed plaques only in the presence of one or other secretagogue. Using this technique we found clear evidence of cells that formed plaques in response to CRH but not AVP (P less than 0.005); CRH or AVP (P less than 0.0001), and CRH and AVP (P less than 0.05). There was no evidence of a corticotrope forming a plaque with AVP but not CRH (P = 0.52). Thus there appears to be functionally distinct classes of corticotropes. These findings have important implications for our understanding of the relative responsiveness of the pituitary to hypothalamic secretagogues and provide a new physiological perspective on recent reports of stress-specific hypothalamic responses regulating ACTH release.

Role of protein kinase-C in the adrenocorticotropin secretory response to arginine vasopressin (AVP) and the synergistic response to AVP and corticotropin-releasing factor by perifused rat anterior pituitary cells

Arginine vasopressin (AVP) stimulates biphasic release of ACTH from anterior pituitary corticotrophs. The response consists of an initial transient spike phase lasting less than 3 min and a subsequent sustained plateau phase that persists for as long as AVP is present. AVP also acts synergistically with CRF on ACTH release. We have previously shown that the initial spike phase of the response mainly requires release of intracellular Ca2+ and is independent of calmodulin, whereas the sustained plateau phase, like the monophasic sustained response elicited by CRF, involves the influx of extracellular Ca2+ via L-type voltage-sensitive Ca2+ channels and activation of calmodulin. We have also shown that the synergism between AVP and CRF does not require extracellular Ca2+ influx. In this study we examined the role of Ca2+/phospholipid-dependent protein kinase-C (PKC) in the two phases of the response to AVP and in the synergism between AVP and CRF. We exploited the observation that prolonged exposure to phorbol esters down-regulates PKC. Dispersed adult male rat anterior pituitary cells were incubated in static suspension culture for 4-5 days, 0.5 microM phorbol 12-myristate 13-acetate (PMA) or 0.0005% dimethylsulfoxide vehicle alone was added, and the incubation was continued for 24 h. The cells were preperifused with PMA-free perifusion medium for 3 h and then perifused with various agents for 10-20 min. Effluent fractions were collected every 30 sec or 1 min and subjected to ACTH RIA. Pretreatment with PMA inhibited the subsequent response to 100 nM PMA and 100 microM dioctanoylglycerol, but not to 5 microM forskolin or to depolarization with 56 mM KCl, demonstrating specific down-regulation of PKC. PMA pretreatment had no effect on the initial spike phase of the response to AVP, but inhibited the sustained plateau phase by 57% (P less than 0.005) and, consequently, the integrated total response by 33% (P less than 0.05). Pretreatment had no effect on the response to CRF. However, pretreatment with PMA completely blocked both phases of the synergistic response to the combination of AVP and CRF. These results indicate that activation of PKC is required for the sustained phase of the response to AVP and both phases of its synergistic interaction with the protein kinase-A pathway, but is not involved in the initial spike phase of the response to AVP, which presumably is mediated by inositol 1,4,5-trisphosphate-stimulated mobilization of intracellular Ca2+, or in the independent activation of the protein kinase-A pathway by CRF.

Roles of intracellular and extracellular calcium in the kinetic profile of adrenocorticotropin secretion by perifused rat anterior pituitary cells. I. Corticotropin-releasing factor stimulation

We examined the effects of removing extracellular Ca2+ (Ca2+e), depleting intracellular Ca2+ (Ca2+i), inhibiting Ca2(+)-dependent calmodulin, blocking voltage-sensitive Ca2+ channels, and combining Ca2+i depletion with exposure to glucocorticoid on the secretion of ACTH by perifused dispersed rat anterior pituitary cells stimulated with ovine CRF and 8-bromo-cAMP (8-Br-cAMP). A time-course analysis of the effect of perifusing the cells for 60 min with Ca2(+)-free medium on 10 nM CRF-stimulated ACTH release revealed that inhibition required about 3 min to begin and about 40 min to reach maximal effect. Within 2 min of restoring Ca2+ to the medium, ACTH secretion rebounded for about 5 min before falling to the pre-Ca2+e removal rate. A similar pattern and time course were observed when Ca2+e was more completely removed by perifusing the cells with Ca2(+)-free medium containing 2 mM EGTA, except that greater suppression was observed. Removing Ca2+e reduced CRF- and 5 mM 8-Br-cAMP-induced ACTH release by 54% and 49%, respectively, and delayed by 1 min the response to 8-Br-cAMP, but not that to CRF. Perifusing 0.2 mM nimodipine, a dihydropyridine Ca2+ channel blocker, before and after restoration of Ca2+ to the Ca2(+)-free medium inhibited ACTH release by 40-48%, and the blockade persisted for at least 70 min after nimodipine was removed from the medium. When intracellular Ca2+ was depleted by perifusing the cells with Ca2(+)-free/EGTA medium containing the Ca2+ ionophore A23187 to facilitate the efflux of Ca2+i, CRF- and 8-Br-cAMP-stimulated ACTH release were reduced by 70% and 71%, respectively, and the responses to both agents were delayed by 1 min. Preperifusion of the cells with 5 microM penfluridol, a calmodulin inhibitor, reduced CRF- and 8-Br-cAMP-induced ACTH release by 54% and 41%, respectively. The combination of Ca2+i depletion and perifusion with 100 nM dexamethasone, a maximally inhibitory concentration, inhibited CRF- and 8-Br-cAMP-stimulated ACTH release by 82% and 83%, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Roles of intracellular and extracellular calcium in the kinetic profile of adrenocorticotropin secretion by perifused rat anterior pituitary cells. II. Arginine vasopressin, oxytocin, and angiotensin-II stimulation

We examined the effects of removing extracellular Ca2+ (Ca2+e), depleting intracellular Ca2+ (Ca2+i), inhibiting cAMP-dependent calmodulin, and blocking voltage-sensitive Ca2+ channels on the secretion of ACTH by perifused dispersed rat anterior pituitary cells. The cells were stimulated with synthetic arginine vasopressin (AVP), oxytocin (OT), and angiotensin-II (AII), all of which are thought to act via the Ca2+/inositol phosphate-dependent protein kinase-C pathway, with synthetic ovine CRF, which acts via the cAMP-dependent protein kinase-A pathway, and with dioctanoylglycerol, which directly activates protein kinase-C. All three secretagogues elicited an initial spike phase ACTH secretory response that peaked within 1 or 2 min and ended within 6 min. AVP and OT also elicited a sustained plateau phase response that lasted for as long as the cells were exposed to the secretagogue, but AII did not. Removal of Ca2+e diminished the initial spike phase by 30-50%, but depletion of Ca2+i virtually abolished it. In contrast, the sustained phase of the response to AVP and OT was abolished by removal of Ca2+e. The effect of dioctanoylglycerol, which elicits a sustained progressive increase in ACTH release, but no initial spike phase, was also greatly inhibited by Ca2+e removal; no greater effect was observed when Ca2+i was depleted. Blockade of L-type voltage-sensitive Ca2+ channels with nimodipine, a dihydropyridine drug, had the same effect as Ca2+e removal on both the initial spike and sustained plateau phases of the response to AVP. Inhibiting cAMP-dependent calmodulin with penfluridol had no effect on the initial spike phase, but reduced the sustained plateau phase of the response to AVP. Removal of Ca2+e or depletion of Ca2+i did not abolish the synergistic ACTH secretory response to the combination of AVP and CRF.(ABSTRACT TRUNCATED AT 400 WORDS)

Kinetic actions and interactions of arginine vasopressin, angiotensin-II, and oxytocin on adrenocorticotropin secretion by rat anterior pituitary cells in the microperifusion system

We have examined the actions and interactions of arginine vasopressin (AVP), angiotensin-II (AII), and oxytocin (OT) on the ACTH secretory response of dispersed rat anterior pituitary cells in a microperifusion system. There was a dose-dependent ACTH secretory response to a 3-min perifusion of AII which reached its maximum 10 sec after the cells were exposed to AII and fell rapidly to baseline within 2 min, despite continued infusion of AII. This brief spike type of pattern is similar to that produced by AVP, but different from the sustained plateau response induced by CRF. The threshold stimulating concentration of AII was about 10(-9) M; the maximally stimulating concentration was not defined, but was 10(-6) M or more. The initial ACTH response to OT was similar, but fell to a plateau 2 min after the cells were exposed to OT and remained constant until perifusion with OT was stopped, after which it fell rapidly to baseline. The threshold stimulating concentration of OT was 10(-8) M; the maximally stimulating concentration was not defined, but was 10(-6) M or more. The ACTH secretory response to 10(-8) M AII was greatly diminished when cells were exposed to 10(-6) AVP or 10(-6) M OT before AII infusion. However, prior exposure to AII had no effect on the magnitude of the ACTH secretory response to either AVP or OT. The effects of simultaneous perifusion of AII and AVP and of AII and OT were additive. When AVP and OT were perifused sequentially, the ACTH secretory response to the peptide that was infused second was completely abolished. Furthermore, the combination of AVP and OT stimulated no greater response than either agent alone. When cells were perifused with the combination of 10(-7) M OT and 10(-7)- to 10(-5)-M concentrations of two potent AVP V1 receptor antagonists, [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-(O-methyl)tyrosine]-Arg8-vasopressin and [1-deaminopenicillamine-2-(O-methyl)tyrosine]-Arg8-vasopressin, both phases of the response to OT were progressively and almost completely inhibited. The initial spike phase was inhibited at lower antagonist concentrations than the sustained plateau phase.(ABSTRACT TRUNCATED AT 400 WORDS)

Primary hypoadrenocorticism in ten cats

Primary hypoadrenocorticism was diagnosed in ten young to middle-aged cats of mixed breeding. Five of the cats were male, and five were female. Historic signs included lethargy (n = 10), anorexia (n = 10), weight loss (n = 9), vomiting (n = 4), and polyuria (n = 3). Dehydration (n = 9), hypothermia (n = 8), prolonged capillary refill time (n = 5), weak pulse (n = 5), collapse (n = 3), and sinus bradycardia (n = 2) were found on physical examination. Results of initial laboratory tests revealed anemia (n = 3), absolute lymphocytosis (n = 2), absolute eosinophilia (n = 1), and azotemia and hyperphosphatemia (n = 10). Serum electrolyte changes included hyponatremia (n = 10), hyperkalemia (n = 9), hypochloremia (n = 9), and hypercalcemia (n = 1). The diagnosis of primary adrenocortical insufficiency was established on the basis of results of adrenocorticotropic hormone (ACTH) stimulation tests (n = 10) and endogenous plasma ACTH determinations (n = 7). Initial therapy for hypoadrenocorticism included intravenous administration of 0.9% saline and dexamethasone and intramuscular administration of desoxycorticosterone acetate in oil. Three cats were euthanatized shortly after diagnosis because of poor clinical response. Results of necropsy examination were unremarkable except for complete destruction of both adrenal cortices. Seven cats were treated chronically with oral prednisone or intramuscular methylprednisolone acetate for glucocorticoid supplementation and with oral fludrocortisone acetate or intramuscular injections of repository desoxycorticosterone pivalate for mineralocorticoid replacement. One cat died after 47 days of therapy from unknown causes; the other six cats are still alive and well after 3 to 70 months of treatment.

Immunocytochemical localization of epidermal growth factor in the developing human respiratory system and in acute and chronic lung disease in the neonate

Cells staining for immunoreactive human epidermal growth factor were sought in the lungs and tracheas of human fetuses from 8 to 24 weeks of gestation. Lungs of liveborn infants from 25 to 40 weeks of gestation (stillborn to 7 months postnatal life), both with and without lung pathology, were also studied. In the early fetal trachea (12 to 15 weeks), many nonciliated cells immunostained for immunoreactive human epidermal growth factor in the lining epithelium. By 16 weeks of gestation this widespread staining was replaced by stained nonciliated single cells or small clusters of cells which were identifiable until 24 weeks. In the few tracheas which were available from liveborn infants who died without evidence of lung disease, stained cells were seldom identified in the lining epithelium after 24 weeks of gestation. In contrast, from 18 weeks until term, tracheal submucosal glands contained scattered cells which immunostained for immunoreactive human epidermal growth factor but which did not appear to be classical mucous cells. Beginning at 20 weeks of gestation, positively staining cells were found occasionally in bronchial lining epithelium, but more often in bronchial submucosal glands. Immunostained cells were never identified in bronchiolar epithelium in normal fetal or newborn lungs. In liveborn infants from 24 weeks onward who developed lung disease, many tracheas were severely damaged. In the presence of extensive denudation of the mucosa or the development of squamous metaplasia, immunostained cells were rarely seen in the lining epithelium. However, even under these conditions stained glandular cells could usually be identified. Stained cells were also present in the necks of those tracheal glands from which new epithelial lining cells appeared to be migrating onto denuded surfaces. Immunostained cells in the bronchial lining epithelium of infants with chronic lung disease were infrequent, just as they were in the fetus, but bronchial submucosal glands contained positively stained cells similar to those in tracheal glands. The appearance and distribution of immunostained cells were similar in the tracheal and bronchial submucosal glands in both normal subjects and those with all stages of lung disease. In contrast to the bronchioles of fetuses and infants without lung pathology, the bronchiolar epithelium of infants with chronic lung disease contained immunostained cells. Immunostained cells were found in areas of migrating dysplastic cells in relining conducting airways.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocorticotropin-independent bilateral macronodular adrenal hyperplasia: an unusual cause of Cushing's syndrome

Inappropriate ACTH secretion with bilateral diffuse or macronodular adrenal hyperplasia is the most common cause of Cushing's syndrome. This report describes a patient with Cushing's syndrome and feminization due to ACTH-independent bilateral macronodular adrenal hyperplasia. A 47-yr-old black man presented with Cushingoid features, diabetes mellitus, hypertension, impotence, and gynecomastia. Urinary cortisol and 17-hydroxycorticosteroid excretion were 94 nmol/mmol creatinine (normal, less than 32) and 5.8 mumol/mmol creatinine (normal, 0.6-3.6), respectively. Both decreased by less than 30% after administration of dexamethasone (8 and 16 mg/day), and urinary 17-hydroxycorticosteroid excretion did not increase after metyrapone (750 mg, orally, every 4 h for six doses). Plasma ACTH was undetectable (less than 1 pmol/L) and was not stimulated by administration of metyrapone or ovine CRH. Serum testosterone was 5.2 nmol/L (normal, 7-30), FSH was 5 U/L (normal, 3-18), LH was 2.8 U/L (normal, 1.5-9.2), and estrone was 767 pmol/L (normal, 55-240). Both adrenal glands were enlarged, with a total weight of 86 g (normal, 8-10), and contained multiple nodules (diameter, greater than 0.5 cm) composed of two active cell types, one of which was also observed between the nodules. Cushing's syndrome with feminization due to ACTH-independent bilateral macronodular adrenal hyperplasia is an unusual process of unknown etiology that should be included with the other known causes of Cushing's syndrome.

Effects of ovine corticotropin-releasing hormone on adrenocorticotropin secretion in the absence of glucocorticoid feedback inhibition in man

We studied 1) the nature of the plasma ACTH response to ovine CRH (oCRH) in the absence of normal glucocorticoid negative feedback inhibition and 2) the cause of the diminished circadian peak in plasma ACTH in normal men the morning after 3-30 micrograms/kg BW doses of oCRH. Placebo or oCRH (3 micrograms/kg BW, iv) was administered as iv injections to five normal men given metyrapone to produce acute glucocorticoid deficiency. Four studies were performed: 1) placebo oCRH plus placebo hydrocortisone (HC), 2) oCRH plus placebo HC, 3) placebo oCRH plus HC, and 4) oCRH plus HC. HC was given as a variable rate iv infusion to mimic the plasma cortisol response to the same dose of oCRH in normal men. Plasma cortisol levels rose only slightly after oCRH, indicating nearly complete blockade of cortisol biosynthesis. Plasma cortisol levels during the HC infusion were similar to those in normal men given 3 micrograms/kg oCRH. There was an exaggerated rise in both the first and second peaks of the plasma ACTH response to oCRH in the metyrapone-treated men. HC infusion did not alter the plasma ACTH response during the first 60 min after oCRH, but markedly attenuated the response thereafter; however, it did not affect the timing of the second peak. This inhibitory effect continued for up to 11 h, which was 2-3 h longer than the period that plasma cortisol levels were increased. Thus, cortisol secreted in response to ACTH released by oCRH modulates, after about a 60-min delay, the continuing release of ACTH. Despite the greater oCRH-induced release of pituitary ACTH in the metyrapone-treated men, the magnitude of their next morning's circadian plasma ACTH peak was similar to that after they received placebo oCRH. Thus, depletion of pituitary ACTH did not appear to explain the diminished circadian peak. Its magnitude was reduced by the combination of oCRH and HC, but not by HC alone. Administration of oCRH, alone or in combination with HC, delayed the onset of the circadian rise, while oCRH, HC, or the combination thereof delayed the time of the circadian peak. Thus, it appears that both the glucocorticoid response to oCRH and direct or indirect effect(s) of oCRH are required to produce these two phenomena.

Immunoreactive human epidermal growth factor concentrations in amniotic fluid, umbilical artery and vein serum, and placenta in full-term and preterm infants

Immunoreactive human epidermal growth factor (IR-hEGF) was measured in samples taken from 27 full-term and 14 preterm infants. The samples included amniotic fluid, amniotic membranes, fetal and maternal sides of the placenta, and matched umbilical artery and umbilical vein serum. Our results demonstrated the presence of IR-hEGF in the human placenta, amniotic fluid and cord blood during the second half of gestation. The increase in placental tissue, amniotic fluid, and cord blood concentration with progressive gestation suggests a possible functional role for EGF during perinatal development.

Proopiomelanocortin gene expression in a pheochromocytoma using upstream transcription initiation sites

The proopiomelanocortin (POMC) gene is expressed in many normal nonpituitary tissues, in addition to the pituitary. POMC-derived peptides have also been detected in many pheochromocytomas. We examined poly(A)+ RNA from 5 pheochromocytomas with a POMC exon 3 riboprobe and show that 3 tumors contained POMC-like mRNAs that were 50 to 350 bases longer than pituitary POMC mRNA. S1 nuclease analyses of tumor poly(A)+ RNA demonstrate that some of the POMC-like mRNAs contain additional segments of 238, 318 or 374 nucleotides derived from the region immediately upstream from the normal transcription initiation site. We conclude that pheochromocytomas express the POMC gene and that the long POMC-like mRNAs in these tumors and, probably, those in normal adrenal and testis arise from transcription initiating at sites upstream from the normal site used in pituitary.

Proopiomelanocortin gene is expressed in many normal human tissues and in tumors not associated with ectopic adrenocorticotropin syndrome

Immunoreactive (IR) POMC peptides have been detected in several human nonpituitary tissues and most pheochromocytomas and lung cancers, including those not associated with ectopic ACTH syndrome. We found IR-ACTH, IR-gamma MSH, IR-beta-endorphin (beta END), and IR-lipotropin in extracts from the following 10 normal human tissues, listed in order of decreasing POMC peptide concentrations: adrenal, testis, spleen, kidney, ovary, lung, thyroid, liver, colon, and duodenum. IR-ACTH, IR-gamma MSH, and IR-beta END were detected in all six pheochromocytomas and all 12 lung tumors (six squamous cell carcinomas, five adenocarcinomas, and one small cell carcinoma) we examined, as well as in a squamous cell carcinoma of the larynx. None of the patients had clinical evidence of ectopic ACTH syndrome. To determine whether these nonpituitary tissues and tumors actually synthesize POMC, rather than simply absorb POMC peptides from plasma, we examined poly(A) RNA prepared from these tissues and total RNA from pituitary by Northern blot hybridization for the presence of POMC-like mRNA with an exon 3 riboprobe. Pituitary contained a single POMC mRNA species of about 1150 bases. A short POMC-like mRNA of about 900 bases was found in all normal nonpituitary tissues, three of five pheochromocytomas, eight of nine lung cancers, and the laryngeal squamous cell tumor. In addition, larger POMC-like mRNA species between 1200 to 1500 bases were detected in adrenal, testis, ovary, placenta, two pheochromocytomas, and three squamous cell lung tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Human urinary epidermal growth factor excretion: age, sex, and race dependence

We measured the urinary excretion of immunoreactive epidermal growth factor (IR-EGF) in random urine specimens obtained from 358 ambulatory patients and normal subjects, aged 18-90 yr, with a homologous EGF RIA. We also measured IR-EGF excretion in 24-h urine collections from 40 additional normal subjects, aged either 20-29 or 60-69 yr, to detect possible artifacts introduced in the analysis of random urine specimens by the age-related decline in the glomerular filtration rate. Urinary IR-EGF excretion decreased in a linear fashion with increasing age. Women excreted more IR-EGF than men, and whites excreted more IR-EGF than blacks of the same age and sex, but the rate of decline with increasing age was similar for all groups. These findings may provide additional insight into the role of EGF in human renal physiology.

Immunoreactive proopiomelanocortin (POMC) peptides and POMC-like messenger ribonucleic acid are present in many rat nonpituitary tissues

Immunoreactive (IR) POMC peptides have been found in several rat nonpituitary tissues. We found IR-ACTH, IR-beta-endorphin (beta END), and IR-gamma MSH in extracts from the following eight rat nonpituitary tissues, listed in order of decreasing POMC peptide concentrations: testis, duodenum, kidney, colon, liver, lung, stomach, and spleen, but not in adrenal or muscle extracts. Concentrations were very low and ranged from less than 0.00003% to 0.0005% of pituitary levels. In testis, duodenum, and colon, IR-gamma MSH and IR-beta END concentrations were only 5-37% of IR-ACTH levels. Gel filtration chromatography showed that IR-ACTH and IR-beta END coeluted in a major peak of 15,000 daltons, which is slightly larger than expected for a C-terminal peptide containing rat ACTH and beta-lipotropin. There were also a minor higher mol wt peak of IR-ACTH and IR-beta END and a minor IR-beta END peak that eluted in the position of mature beta END. There was no peak of IR-ACTH that corresponded to the size of mature ACTH. To determine whether these nonpituitary tissues also contained a POMC-like mRNA, which would confirm that the peptides were synthesized locally within the tissues, we examined poly(A) RNA prepared from 10 nonpituitary tissues and total RNA from pituitary by Northern blot hybridization for the presence of a POMC-like mRNA with an exon 3 riboprobe. Pituitary contained a single POMC mRNA species of about 1000 nucleotides. A short POMC-like mRNA of about 800 bases was found in all nonpituitary tissues, except spleen and muscle. Compared to POMC mRNA levels in pituitary, the concentration of POMC-like mRNA was 0.5% in testis and 0.03-0.07% in the other tissues. The ratio of POMC-like mRNA to IR-POMC peptide concentrations in nonpituitary tissues was at least 1000 times greater than that in the pituitary. We conclude that the POMC gene is expressed in many nonpituitary tissues and that either the short POMC-like mRNA is translated much less efficiently or POMC peptides are released or degraded much more rapidly in nonpituitary tissues than in the pituitary.

Effects of several in vitro systems on the potencies of putative adrenocorticotropin secretagogues on rat anterior pituitary cells

We examined the effects of several in vitro experimental systems on the apparent potencies of putative secretagogues for stimulating ACTH release from rat anterior pituitary cells. Cells were prepared by trypsin digestion and gentle mechanical dispersion. Aliquots of the same cell preparations were tested in 1) a microperifusion system immediately after dispersion (day 0), 2) the same microperifusion system after 4 days of static suspension culture on a layer of Sephadex G-10 gel particles (day 4), 3) a static suspension system after 4 days of static suspension culture, and 4) a static monolayer system after 4 days of monolayer culture. Ovine CRF stimulated release of similar amounts of ACTH in all of the systems on days 0 and 4, except in one experiment, in which the response was less on day 4. Arginine vasopressin (AVP), oxytocin, and angiotensin II all appeared to be more potent in day 4 than in day 0 cells in the perifusion system, and the synergism of AVP with ovine CRF was also increased. Dioctanoylglycerol, which directly activates protein kinase-C, and forskolin, which directly activates adenylate cyclase, both stimulated greater release in day 4 cells. The mechanism(s) responsible for the difference in the responses of day 0 and day 4 cells is unknown. Epinephrine had only a small effect in the microperifusion system, but both epinephrine and norepinephrine had potencies comparable to AVP in the static suspension and monolayer systems. This was not due to prolonged exposure to the catecholamines, suggesting that these agents may act on other anterior pituitary cells to release metabolic products that secondarily stimulate the corticotrophs to release ACTH. The same situation appears to be true for atrial natriuretic factor. Gastrin-releasing peptide, its bioactive COOH-terminal half, which was active in a rat urinary bladder smooth muscle assay, its amphibian analog, bombesin, and cholecystokinin (26-33) were devoid of ACTH-releasing activity in all of the systems, in contrast to the findings of others. Since 4-day culture of dispersed cells improved most of their responses and diminished none, we postulate that they may more closely resemble normal pituitary cells in function, and since cellular metabolites are unlikely to accumulate in the interstitial fluid of the pituitary gland, we propose that the secretory functions of cells in perifusion systems may more closely resemble those in the pituitary gland in situ than they do in static incubation systems.