Influence of acute stress and the adrenal axis on regulation of LH and testosterone in the male rhesus monkey (Macaca mulatta)

In order to determine the mechanism by which stress may affect the secretion and function of luteinizing hormone (LH) in primates, the response of the adrenal and gonadal axes was followed in male rhesus monkeys during brief restraint in primate chairs and during various hormone treatments. To further assess the responsiveness of the gonadal axis, gonadotropin releasing hormone (GnRH) was administered during the experiments. Corticosteroid levels were elevated throughout the first restraint trial as compared to those in subsequent trials. LH was elevated in the first sample of the first trial as compared to that in the following trials. The responses of LH to GnRH were equivalent in all trials, while the testosterone response to GnRH was attenuated in the first trial. A single injection of adrenocorti-cotropin (ACTH, 40 IU), while increasing circulating corticosteroids similarly to that observed during the first restraint trial, failed to cause an acute initial release of LH. However, ACTH did lower the testosterone response to GnRH. Following 5 days of ACTH treatment (40 IU twice daily), basal LH was suppressed, and the testosterone response to GnRH was decreased. Following 5 days of cortisol injections (100 mg twice daily), basal LH and testosterone were suppressed, but again only the testosterone response to GnRH was attenuated. Acute restraint stress, acting by some mechanism other than the activation of adrenal axis, stimulates a transient release of LH. While the stress-stimulated release of corticosteroids failed to affect the LH response following GnRH administration, it did act directly on the testes to prevent the normal release of testosterone. Finally, chronic elevation of corticosteroids, produced by ACTH or cortisol administration, suppressed basal serum LH and attenuated the response of testosterone to GnRH.     

Further evaluation of IGF-I responsiveness to ACTH in children affected with IGHD.

In our previous studies we had demonstrated that, in children affected with isolated GH deficiency (IGHD), a short-term recombinant growth hormone (rGH) therapy increases the 11-deoxycortisol (S) secretion and induces an IGF-I responsiveness to the ACTH challenge. The aim of the present study was to further investigate the mechanisms by which IGF-I is secreted after ACTH challenge in children affected with IGHD by correlating IGF-I versus cortisol (F) time courses after ACTH administration. Ten children affected with IGHD were subjected to rGH therapy (4 IU/day subcutaneously) for 10 days. The responsiveness of IGF-I, F and S to the ACTH 1-17 test were evaluated before and at the end of the therapy. No IGF-I response to the ACTH test was recorded in the patients before the rGH treatment, whereas after rGH administration ACTH induced a significant IGF-I release (p < 0.001) which started at the 1st hour, reached a peak value between the 5th and 6th hours and disappeared at the 10th hour. In conclusion, our study confirms that a short-term rGH therapy induces an IGF-I responsiveness to ACTH and helps to better define the kinetics and the mechanism of this IGF-I response to ACTH.     

La puberté surrénalienne

The androgens produced by the adrenal glands are mainly Δ5 steroids, first dehydroepiandrosterone (DHA) and its sulfate (DHAS). Adrenal androgens, very high at birth, decrease rapidly the first few months of life, remaining very low from 1 to 6 years of life. Adrenarche is defined as the changes in the pattern of adrenal secretions which occur several years before the onset of gonadal puberty (gonadarche). Developmental patterns of adrenal androgens differ markedly among species and only the chimpanzee exhibits an adrenarche comparable to that of man. Adrenarche starts in both sexes around age 7. The increase in DHA/DHAS has a rather abrupt onset and is thereafter progressive. Before the onset of gonadarche mean levels of DHA and DHAS have increased by about 10 and 20 fold respectively. The prepubertal rise in plasma Δ⁵-androgens is accompanied by that of Δ4-androstenedione and 11β-hydroxy-Δ⁴-androstenedione occurring likely at about the same time but being very progressive and more modest are only significant after age 8 in both sexes. Adrenal androgens continue to rise during puberty. Plasma levels of DHA and DHAS continue to rise from pubertal stages 1 to 5 and remain similar in both sexes until age 15. At pubertal stage P5, plasma DHA levels are similar to that seen in young adults with no sex difference while that of DHAS continue to rise in boys and become significantly higher than in girls. Developmental changes in adrenal androgen secretions are also observed in the response to ACTH stimulation. Whether estimated as absolute levels or Δ of response, the rise in all unconjugated adrenal androgens to a short or prolonged ACTH stimulation, is greater with increasing age, with no sex difference, and is somewhat correlated to basal levels. Plasma levels of DHAS do not vary significantly the 2 hours following a bolus injection of ACTH (21, 34) but its response to longterm (3-days) ACTH stimulation is also increasing with age. Morphological and functional changes in the adrenal cortex also occur during development. Focal development of aZona reticularis starts at 5 years of age, and progressively becomes continuous. The development of the zona reticularis is parallel to the increase in adrenal androgen secretions, and is completed only by age 15. This is accompanied by a rise in 17-hydroxylase and 17,20-desmolase activity in the adrenals. In a normal timing of physiological events, the onset of adrenarche occurs several years before the onset of gonadarche, 2–3 years in girls and 3–4 years in boys. This relation does not preclude that the processes are independent events. Indeed, the onset of adrenarche and gonadarche are dissociated in a variety of disorders of sexual maturation Adrenal androgen secretions are under the control of ACTH, as shown by a series of observations. However, the specific increase of adrenal androgen secretions during development without any detectable change in ACTH stimulation, the dissociation between adrenarche and gonadarche in several conditions, have led to postulate that the biochemical differentiation of the zona reticularis may require the action of an «adrenal factor» in addition to ACTH. Among the proposed «trophic» factors of adrenal androgen secretion, LH/FSH and estrogens are no longer believed to be involved. The evidences for the existence of a separate and specific pituitary cortical androgen-stimulating hormone (CASH) are not yet convincing. Prolactin, linked to nutritional status, may stimulate the activity of the adrenal hydroxysteroid sulfotransferase. The functional zonal theory» is attractive, but it does not explain why changes in adrenal androgens occur at a given age. Finally, the occurrence of familial cases of premature pubarche, the study of the changes in adrenal androgens in monozygotic or dizygotic twins and the observation that in idiopathic delayed puberty the delay in adrenarche is only one part of a generalized growth and developmental delay, strongly suggests that maturation of the adrenal cortex is regulated, at least in part, by genetic factors. The physiological importance of adrenal androgens remains a matter of controversy. Classical “dogma” dictates that adrenal androgens are responsible for pubic hair development. It has also been suggested that they contribute to somatic growth or epiphyseal advancement in childhood. This is mainly based on the observation that premature adrenarche is accompanied by premature pubarche, tall stature and advanced bone age. However, adequate androgen secretion alone does not ensure normal sexual hair development in many patients with gonadal dysgenesis. Moreover, in children with a lack or delayed adrenarche long-term treatment with DHAS at dosages such as to restore normal levels for age, failed to induce growth of sexual hair or any change in growth rate, bone maturation velocity, or to advance puberty. Although new hypotheses favour the view that Δ5-androgens, particularly Δ⁵-androstenediol, have some characteristic properties of estrogens, the physiological role of adrenal androgens, if any, remains to be established. DHAS may well be only a prohormone. There are ample evidences that all tissues possess active sulfatases which transform it into DHA, a steroid with high turn-over. Administration of DHA to experimental animals has shown beneficial effects on various endocrine-metabolic parameters, enhanced immunoprotective functions and reduced carcinogenesis. DHA prevents diabetes in genetically diabetic and obese mice. The importance ofin vivo andin vitro experimental findings is underscored by epidemiological data showing that low DHA levels are correlated with increased cardiovascular morbidity in men, breast cancer in women and a decline in immune competence. Human studies are at the moment controversial. It remains possible that DHAS influence breast cancer risk earlier in life, and/or that there are more complex interactions with other hormones or the intracellular metabolism of DHA/DHAS. Indeed, the tissue concentrations of DHAS may be important since it may act indirectly via its metabolism into estradiol or other steroids. Further long-term studies are needed to conclude whether DHA/DHAS are a youth fountain.     

Insulin hypoglycemia test and releasing hormone (corticotropin-releasing hormone and growth hormone-releasing hormone) stimulation in patients with pituitary failure of different origin

To investigate the efficacy of endocrine evaluation in diagnosing and localizing the cause of anterior pituitary failure, 17 patients with suprasellar space-occupying lesions, 4 patients with intrasellar tumors, 8 patients with no detectable anatomical lesion, 1 patient with posttraumatic failure and 1 patient with septooptical dysplasia were investigated. Endocrine evaluation consisted of measuring adrenocorticotropic hormone (ACTH), cortisol, and growth hormone (GH) levels during insulin hypoglycemia test (IHT) and after administration of corticotropin-releasing hormone (CRH) and growth hormone-releasing hormone (GRH). In addition, basal prolactin levels, gonadal and thyroid function were evaluated. The results showed that 4 of 17 patients with suprasellar tumors had normal ACTH and GH responses during IHT and after releasing hormone (RH) administration. Five of these patients had a normal ACTH or cortisol rise but no GH response during IHT. All 5 had a normal ACTH and 3 had normal GH rise after RH. Seven patients with suprasellar tumors had no ACTH or GH response during IHT, but all had an ACTH response to CRH. Only 3 of this group had a GH response to GRH. There was one exception of a patient who showed a GH and ACTH rise during IHT but only a blunted ACTH and no GH rise after RH administration. Four patients with pituitary failure and no demonstrable lesion had an ACTH rise after CRH but no GH rise after GRH, whereas in 3 patients with isolated ACTH deficiency no ACTH rise after CRH was seen. In 4 patients with nonsecreting pituitary tumors normal ACTH responses to IHT and CRH were seen, whereas GH rose during IHT only in 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)     

日本鳗鲡雌鳗卵巢发育期间肌肉脂肪酸的组成及消耗

研究采用3种不同的处理方式(I&GD、I&nGD和A&nGD)对雌鳗处理后,进行了生物学相关参数、肌肉脂肪酸组成和含量变化测定分析.研究结果表明,日本鳗鲡在性腺发育期间,体重一直呈一个下降的趋势,直到产卵前,才显著高于野生海鳗.该现象被称为水合反应.实验结束时,3个实验组的脂肪总量均有不同程度的下降,其中,I&GD组下降最多,占总脂肪的66.55%;其次是A&nGD组,占总脂肪的43.76%;下降最少的是I&nGD组,占总脂肪的34.68%.研究对日本鳗鲡的肌肉共测出了17种脂肪酸,SFA 7种、MUFA 2种、PUFA 8种.其中,MUFA虽然只有2种,但在脂肪酸总量中占的百分比却较高达38.02%,而且它们的消耗与性腺发育和基础代谢有关,与雌鳗的游泳耗能无关.在8种PUFA中,AA的变化很特殊.实验期间,它在日本鳗鲡肌肉内是一个积累和消耗的动态过程.而且,积累程度与雌鳗的游动有关,游动越多,积累越多.EPA虽然能被检出,但量很低,而且各组间的变化无明显规律.DHA在日本鳗鲡肌肉中的含量达到123.91 mg/g干肌肉,占总脂肪的32.52%.卵巢发育所消耗的量也很多,I&GD组在卵巢发育结束后,下降到10.59 mg/g十肌肉.相关性分析发现.虽然总脂肪酸、PUFA、DHA和EPA与GSI间均存在一定程度的负相关性,但关系最密切的是DHA,其r=-0.952(P<0.01,n=5),关系最小的是EPA,其r=-0.882(P<0.05,n=5).因此分析认为DHA是日本鳗鲡性腺发育所需的最主要的一种脂肪酸.对能量分布进行综合分析后认为,日本鳗鲡在人工诱导性腺发育期间,基础代谢所需的脂肪量(LBM)占总脂肪量的34.68%,性腺发育所需脂肪量(LGD)占总脂肪量的32.49%,运动耗能所需脂肪量(LM)占总脂肪量的9.79%.因此认为,日本鳗鲡在不摄食的情况下,肌肉中的脂肪不仅能提供性腺发育所需的营养物质,而且还能满足洄游2000海里到达产卵场所需的能量.     

Activation of adrenal function in fetal sheep by the infusion of adrenocorticotropin to the fetus in utero

We determined whether ACTH1-24, infused into fetal lambs at a rate that is known to cause premature labor, elicits changes in the responsiveness of the fetal adrenal glands, and alters the pattern of corticosteroid output. Plasma cortisol (F), corticosterone (B) and progesterone (P4) were measured during 72 h of infusion of saline or ACTH (10 micrograms/h) beginning on Day 127 of pregnancy. Adrenals were then dispersed into isolated cells, and the output of F, B and P4 after exogenous ACTH determined in vitro. Plasma concentrations of F and B were higher in ACTH-treated fetuses. The increment in F (5-to 7-fold) was greater than that in B (2-fold) such that the F:B ratio in plasma of ACTH-treated fetuses on Days 2 and 3 of infusion was 2.5 times higher than in controls. After 72 h of infusion, the adrenal weights in ACTH-treated fetuses (741 +/- 38 mg, +/- SEM; n = 4) were greater than in the control animals (349 +/- 11 mg). There was a significant effect of ACTH pretreatment in vivo on F output by isolated adrenal cells in vitro. Mean increments in F output after addition of ACTH1-24 (5000 pg/ml) in vitro rose from 368 +/- 235 pg/50,000 cells in controls, to 64,639 +/- 19,875 pg/50,000 cells after ACTH in vivo. There was no significant effect of ACTH in vivo on B output in vitro; the ratio of F:B output, either in the absence or presence of ACTH in vitro, was significantly higher in cells from ACTH-pretreated fetuses. There was a significant effect of in vivo ACTH on in vitro P4 output. After ACTH treatment in vivo there was an increase in the vitro output ratio of F:P4, but no change in the output ratio of B:P4. We conclude that ACTH treatment of the fetal lamb in vivo results in activation of fetal adrenal function, increased fetal adrenal responsiveness to ACTH, and directed corticosteroid biosynthesis towards cortisol. Our results are consistent with an increase in fetal adrenal 17 alpha-hydroxylase activity after ACTH treatment.     

Regulation of baboon fetal adrenal androgen production by adrenocorticotropic hormone, prolactin, and growth hormone

Factors other than adrenocorticotropic hormone (ACTH) are thought to influence fetal adrenal steroidogenesis during primate pregnancy. Therefore, we determined the effects of prolactin (Prl), growth hormone (GH), and human chorionic gonadotropin (hCG) as well as ACTH on steroid secretion by collagenase-dispersed baboon fetal adrenal cells. Adrenal glands were obtained from seven baboon (Papio anubis) fetuses following cesarean section at Day 100-107 of gestation (term = Day 184). Tissue was minced with a fine scissors and cells were dispersed with 0.2% collagenase, then washed with Medium 199 containing penicillin/streptomycin. Cells (0.5 X 10(4)) were placed in 4 ml Medium 199 with or without 10 nmol ovine Prl, ovine GH, or ACTH, or 50 nmol hCG. After 18 h incubation (37 degrees C), cells were separated by centrifugation and the quantities of cortisol (F), dehydroepiandrosterone (DHA), and DHA-sulfate (DHAS) secreted into the medium were determined. In controls, DHA secretion [224 +/- 96 ng/(24 h X 10(5) cells] was greater (P less than 0.05) than that of DHAS (20 +/- 12) and F (14 +/- 12). Adrenocorticotropic hormone, Prl, and GH stimulated (P less than 0.05) DHA secretion by 370% +/- 71%, 215% +/- 61%, and 292% +/- 73%, respectively; hCG was not effective. Due primarily to the relatively low secretion rates, DHAS and F secretion were not altered by hormonal treatment. Moreover, addition of 20 nmol progesterone to the medium in the presence or absence of ACTH did not influence F production. These findings indicate that the baboon fetal adrenal at midgestation does not utilize placental progesterone for F synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Docosahexaenoic acid is an antihypertensive nutrient that affects aldosterone production in SHR.

The effects of dietary docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid, on blood pressure and some pressure-regulating systems were measured in young spontaneously hypertensive rats (SHR). Plasma aldosterone and corticosterone levels, adrenal aldosterone production in vitro, and characteristics of adrenal angiotensin receptors were measured after 6 weeks of diet. Renal cytochrome P450 (CYP) 4A gene expression and arachidonic acid metabolism by renal microsomes were also investigated. Plasma cholesterol, triglycerides, and high-density lipoprotein cholesterol were measured. Diets contained either corn/soybean oil alone (CSO), or oil enriched with DHA. After 6 weeks, rats fed DHA had systolic blood pressures averaging 34 mmHg less than controls (P < 0.001). Plasma aldosterone levels were 33% lower in the DHA-fed animals than in controls (22 +/- 3 vs. 33 +/- 3.7 ng/dl, P < 0.05). Plasma levels of corticosterone were 18% lower in animals fed DHA than in controls, but this difference was not statistically significant. Adrenal glomerulosa cells from DHA-fed rats produced less aldosterone in vitro in response to angiotensin II, ACTH, or potassium. The difference was less marked when aldosterone production was stimulated by supplying exogenous corticosterone, suggesting an effect of DHA on postreceptor steps in signal transduction or the early pathway of aldosteronogenesis. We found no significant differences in angiotensin receptor subtype, number, or affinity. Production of arachidonic epoxides by renal microsomes was 17% lower in DHA-fed animals than in controls (P < 0.05). Renal cortical mRNA levels of CYP4A genes and formation of 19- and 20-hydroxyeicosatetraenoic acid (HETE) did not differ between dietary groups. Plasma total cholesterol and high-density-lipoprotein (HDL) levels were significantly reduced in SHR fed the DHA supplement, but triglyceride levels were not significantly different. The effects of DHA on steroid and eicosanoid metabolism may be part of the mechanism by which this fatty acid prevents some of the hypertension in growing SHR.     

Sex-differences in adrenocortical responsiveness during development in rats

It is known that the stress hyporesponsive period (SHRP), which seems to be related to an immature hypothalamo-pituitary-adrenal (HPA) regulatory system, occurs during the first 2 weeks after birth in rats. In the present study, we investigated the effects of sex-steroid hormones on adrenocortical responsiveness to adrenocorticotropic hormone (ACTH) in neonatal rats. The levels of cyclic adenosine 3',5'-monophosphate (cAMP), corticosterone, and adenylate cyclase activity increased with the dose of ACTH in adrenal cells of males and females in vitro. The ACTH responsiveness in adrenal cells increased with age (7-35 days of age), that is, the loss in responsiveness to ACTH just after birth began to recover in 14-35-day-old rats, but the responsiveness in 14-day-old rats was attenuated in males compared with females. Although castration markedly augmented the responsiveness in male rats, testosterone-replacement in the castrated male rats inhibited the enhancement. Furthermore, the responsiveness in 14-day-intact female rats was suppressed by treatment with testosterone. Expression levels of ACTH receptor mRNA in adrenals increased with age in the female rat, but not in the male. Castration enhanced the level of ACTH receptor mRNA to three-fold of that in intact male rats at 14 days of age, but replacement treatment with testosterone in castrated male rats lowered the elevated levels. Testicular androgens are thought to evoke a gender-specific response in neonates, and the temporal decrease of adrenal ACTH-responsiveness might be due to the topically immature adrenal system as well as the central nervous system in mammals.     

Involvement of the suprachiasmatic nucleus in diurnal ACTH and corticosterone responsiveness to stress

We explored the contribution of the suprachiasmatic nucleus (SCN) in ACTH and corticosterone (CORT) diurnal responsiveness of the rat to restraint stress applied either in the morning (AM) or in the evening (PM). Ablation of the SCN caused the diurnal rhythmicity of the CORT response to disappear but had no effects on AM vs. PM differences in the ACTH response. Stress-response curves in SCN-lesioned rats that had prestress levels of CORT either in the AM range or in the PM range, when compared with those obtained for AM and PM controls, showed that the SCN differentially regulates the stress response depending on the underlying secretory activity of the adrenal cortex. When basal CORT secretion is at its lowest, the SCN inhibits CORT responsiveness to stress by controlling pituitary corticotrophs; but when it is at its highest, it has a permissive action that will bypass the hypophysis and reach the adrenals to adjust the response of the gland to ACTH.     

Effects of ACTH on plasma levels of adrenal steroids in essential hypertension.

Plasma concentrations of progesterone (P), deoxycorticosterone (DOC), 17-hydroxyprogesterone (17-OH P), corticosterone (B), deoxycortisol (S), cortisol (F) and aldosterone (A) in 8 control subjects (mean age: 40.5 years) and 10 patients with essential hypertension (EH) (mean age: 48.5 years) were determined before, 4 and 8 hours after an infusion of ACTH at a rate of 25 units per 8 hours. Secretion rates (SR) of 18-hydroxy-11-deoxycorticosterone (18-OH DOC) were measured 24 hours before and again on the day of ACTH infusion. All subjects were studied on the fourth day of a diet containing 135 mEq of sodium and 90 mEq of potassium. There was no statistically significant difference between 8 control subjects and 10 patients with EH in the 7 plasma steroid levels and the SR of 18-OH DOC before ACTH infusion. The mean plasma P response to ACTH was slightly lower in controls than in patients with EH, while that of 17-OH P (in male subjects) was slightly higher. The mean plasma B response was significantly lower after 4 hours of ACTH infusion (p less than 0.01), while that of DOC was significantly higher after 8 hours of ACTH infusion (p less than 0.05) in patients with EH. The mean plasma S rose significantly more in patients with EH (p less than 0.025) at 4 and 8 hours after ACTH infusion. The mean plasma F response to ACTH infusion was slightly lower in patients with EH than in controls. The mean response of 18-OH DOC SR to ACTH infusion was slightly higher in patients with EH than in controls. The mean plasma A response was significantly higher in patients with EH than in controls 4 (p less than 0.05) and 8 hour (p less than 0.001) after an ACTH infusion. These results could be explained in part by abnormalities in the 17- and 11-hydroxylase systems, and that the abnormality in 11-hydroxylation was more pronounced than that in the 17-position. Furthermore, we suspect that the sensitivity of adrenal aldosterone to ACTH might be increased or another accelerated pathway to aldosterone biosynthesis might exist in patients with EH.     

Increased adrenal steroid secretion in response to CRF in women with hypothalamic amenorrhea

OBJECTIVE: To evaluate adrenal steroid hormone secretion in response to corticotropin-releasing factor (CRF) or to adrenocorticotropin hormone in women with hypothalamic amenorrhea. DESIGN: Controlled clinical study. SETTING: Department of Reproductive Medicine and Child Development, Section of Gynecology and Obstetrics, University of Pisa, Italy. PATIENT(S): Fifteen women with hypothalamic amenorrhea were enrolled in the study. Eight normal cycling women were used as control group. INTERVENTION(S): Blood samples were collected before and after an injection of ovine CRF (0.1 microg/kg iv bolus) or after synthetic ACTH (0.25 mg iv). MAIN OUTCOME MEASURE(S): Plasma levels of ACTH, 17-hydroxypregnenolone (17OHPe), progesterone (P), dehydroepiandrosterone (DHEA), 17-hydroxyprogesterone (17OHP), cortisol (F), 11-deoxycortisol (S) and androstenedione (A). RESULT(S): Basal plasma concentrations of ACTH, cortisol, 11-deoxycortisol, DHEA and 17OHPe were significantly higher in patients than in controls, whereas plasma levels of progesterone and 17-OHP were significantly lower in patients than in controls. In amenorrheic women the ratio of 17-OHPe/DHEA, of 17-OHPe/17-OHP and of 11-deoxycortisol/cortisol were significantly higher than in controls, while a significant reduction in the ratio of 17-OHP/androstenedione, of 17-OHP/11-deoxycortisol was obtained. In response to corticotropin-releasing factor test, plasma levels of ACTH, cortisol, 17-OHP, 11-deoxycortisol, DHEA and androstenedione were significantly lower in patients than in controls. In response to adrenocorticotropin hormone, plasma levels of 17-OHP, androstenedione and androstenedione/cortisol were significantly higher in patients than in controls. CONCLUSIONS: Patients suffering for hypothalamic amenorrhea showed an increased activation of hypothalamus-pituitary-adrenal (HPA) axis, as shown by the higher basal levels and by augmented adrenal hormone response to corticotropin-releasing factor administration. These data suggest a possible derangement of adrenal androgen enzymatic pathway.     

Response of the interrenal to adrenocorticotropic hormone after short-term thyroxine treatment of coho salmon (Oncorhynchus kisutch)

The effects of experimentally elevated plasma thyroxine levels on the subsequent response of interrenals of coho salmon (Oncorhynchus kisutch) to adrenocorticotropic hormone (ACTH) in vitro were examined. Animals were treated with thyroxine by immersion (200 micrograms/L) for 3 days, which resulted in physiological elevations in circulating thyroxine. In animals treated before the parr-smolt transformation was completed (early smolts), thyroxine had no effect on plasma cortisol levels but significantly enhanced the sensitivity of the interrenal to ACTH in vitro. In animals treated after the period of smoltification (postsmolts), plasma cortisol levels were significantly higher than those of controls; both experimental and control animals had plasma cortisol levels higher than normally observed at this stage of development. The response of the interrenals of thyroxine-treated postsmolts to ACTH in vitro was significantly lower than that of controls. Results from the experiments using early smolts are in agreement with studies in other vertebrates showing that thyroid hormones are involved in maintaining the normal functioning of corticosteroidogenic tissue and suggest that thyroid hormones may be involved in the activation of the interrenal that occurs during smoltification. The results obtained using postsmolts are more difficult to interpret because of the possibility that these animals were physiologically stressed by the treatment. Increased ACTH release in vivo resulting from stress may have led to a depression of interrenal sensitivity to ACTH in vitro and may have masked a refractoriness of the pituitary-interrenal axis to thyroxine.     

Adrenal responsiveness and social status in intact and ovariectomized Macaca fascicularis

Plasma cortisol (F) response to intravenous adrenocorticotropin (ACTH) infusion (following dexamethasone suppression) was examined in adult female Macaca fascicularis that had been living for 22 months in social groups consisting of four to six females and one male. A portion of these females were ovariectomized (n = 21), while the rest were reproductively intact (n = 23). The social behavior of all animals was monitored with a focal sampling procedure, and dominance ranks were determined on the basis of fight outcomes. Further, intact females were swabbed vaginally to determine onset of menstruation and were sampled for plasma progesterone (P) every three days during the luteal phase of their cycles. Among the results was that the plasma F response to ACTH infusion was greater in subordinate animals than in dominants (P < .02). Subordinates and dominants did not, however, differ in plasma F measured at baseline. It was found further that plasma F concentrations were greater in ovariectomized than in intact females at baseline and following ACTH injection (P < .01). Finally, there was an appreciable elevation in plasma F across all animals during the 15- and 30-minute post-ACTH injection measurements (P < .01). Subsequent analyses of data from intact females showed interrelationships among dominance rank, reproductive function (indicated by luteal phase plasma P concentrations), adrenal size, and adrenal response to ACTH infusion. These data indicated that subordinate females were at a reproductive disadvantage compared to dominants, a result that may have been mediated, in part, by the increased adrenal size and enhanced adrenal responsiveness of subordinate females.     

Ontogenetic diurnal variation of adrenal responsiveness to ACTH and stress in rats

We performed studies in 8-, 16-, 24-, 30 and 35-day-old Wistar rats at 8.00 h (AM) and 20.00 h (PM) to investigate the relationship between the diurnal variations of basal plasma corticosterone (compound B, CB) and its responses to ACTH and ether stress during the postnatal period. Basal plasma CB levels increased at PM from 8 to 35 days of age and an AM-PM difference was observed at 16 days. Although an AM-PM difference in CB responsiveness to ACTH was detected only at 24 and 35 days, ACTH induced an increasingly higher CB response at PM than at AM from 8 to 35 days. A stress-induced CB response was observed starting at 8 days of age and presented an age-dependent increase; however, no AM-PM difference was observed at any age. The stress-induced CB levels were higher than ACTH-induced CB values at all ages tested except at PM in 8-day old rats. These data demonstrate that the basal CB levels and adrenal sensitivity to ACTH rise during the evening as a function of neonatal development.     

DHA supplementation during the perinatal period and neurodevelopment: Do some babies benefit more than others?

A dietary supply of docosahexaenoic acid (DHA, 22:6n-3) during the perinatal period is postulated to be important for the neurodevelopmental outcome of children. This paper reviews the results of two large scale intervention trials in which equivalent dietary doses of DHA were assessed. One trial assessed the ex utero effect of DHA supplementation for preterm infants born <33 weeks' gestation while the other trial assessed the in utero effect of DHA supplementation during the second half of pregnancy. Ex utero DHA supplementation, which aimed to achieve the level of DHA accumulation that would occur in the womb, appeared more effective in improving the neurodevelopmental outcome of preterm children rather than in utero DHA supplementation of unborn infants. Significant treatment by sex and treatment by birth weight interactions were noted indicating that boys and girls respond differently to DHA supplementation and that birth weight may also be important in predicating the DHA responsiveness.     

Testicular and adrenocortical function in healthy men and in men with benign prostatic hyperplasia.

The influence of aging upon serum concentrations of testicular steroids, sex hormone binding globulin (SHBG) and pituitary hormones and on adrenal steroid levels and adrenal steroid response to ACTH was studied in 81 healthy men aged 20-87 years. These endocrine variables were also compared in 43 patients with benign prostatic hyperplasia (BPH), aged 58-89 years and in a subgroup of 41 men, aged 58-87 years, from the above mentioned reference population. The normal endocrine aging was characterized by a rise in SHBG levels, decreasing levels of testicular steroids and non-SHBG-bound testosterone (NST) and increasing gonadotropin levels and decreasing concentrations of total estrone. Adrenal androgen levels decreased in the presence of unchanged levels of cortisol and the adrenal steroid response to ACTH changed by decreasing increments in dehydroepiandrosterone (DHA) and increasing increments in 17 alpha-hydroxyprogesterone (17OHP). With the exception of the alterations in SHBG and adrenal androgens, all these changes were finished before the seventh decade of life. BPH patients had elevated levels of testosterone and NST in the presence of normal SHBG and gonadotropin levels, elevated levels of DHA and DHA sulfate (DHAS) in the presence of normal cortisol levels, a "younger" pattern of adrenal steroid response to ACTH as judged from the increments in DHA and 17OHP, elevated ratios between estrone and 4-androstene-3,17-dione suggesting an increased peripheral aromatization and subnormal prolactin levels. BPH patients may be considered as "endocrinologically younger" than healthy subjects. DHA and especially its proximate metabolite 5-androstene-3 beta, 17 beta-diol exert powerful estrogenic effects on the receptor level. Thus the elevated levels of DHA and DHAS in the BPH patients may create an hyperestrogenic condition in addition to the slight hyperandrogenicity caused by the elevated NST levels. Both endocrine aberrations may play a role in the etiology of BPH, in accordance with the dual sex steroid sensitivity of the periurethral glands.     

Infusion of ACTH stimulates expression of adrenal ACTH receptor and steroidogenic acute regulatory protein mRNA in fetal sheep

The late-gestation plasma cortisol surge in the sheep fetus is critical for stimulating organ development and parturition. Increased adrenal responsiveness is one of the key reasons for the surge; however, the underlying mechanisms are not fully understood. Our recent studies suggest that ACTH-mediated increased expression of ACTH receptor (ACTH-R) and steroid acute regulatory protein (StAR) may play a role in enhancing responsiveness. Hence, we examined effects of ACTH infusion in fetal sheep on mRNA expression of these two mediators of adrenal responsiveness and assessed the functional consequences of this treatment in vitro. Fetuses of approximately 118 and 138 days of gestational age (dGA) were infused with ACTH-(1-24) for 24 h. Controls received saline infusion. Arterial blood was sampled throughout the infusion. Adrenals were isolated and analyzed for ACTH-R and StAR mRNA, or cells were cultured for 48 h. Cells were stimulated with ACTH, and medium was collected for cortisol measurement. Fetal plasma ACTH and cortisol concentrations increased over the infusion period in both groups. ACTH-R mRNA levels were significantly higher in ACTH-infused fetuses in both the 118 and 138 dGA groups. StAR mRNA increased significantly in both the 118 and 138 dGA groups. Adrenal cells from ACTH-infused fetuses were significantly more responsive to ACTH stimulation in terms of cortisol secretion than those from saline-infused controls. These findings demonstrate that increases in circulating ACTH levels promote increased expression of ACTH-R and StAR mRNA and are coupled to heightened adrenal responsiveness.     

Prenatal testosterone treatment alters LH and testosterone responsiveness to GnRH agonist in male sheep

Although evidence is accumulating that prenatal testosterone (T) compromises reproductive function in the female, the effects of excess T in utero on the postnatal development of male reproductive function has not been studied. The aim of this study was to assess the influence of prenatal T excess on age-related changes in pituitary and gonadal responsiveness to GnRH in the male sheep. We used the GnRH agonist, leuprolide (10 microg/kg), as a pharmacologic challenge at 5, 10, 20 and 30 weeks of age. These time points correspond to early and late juvenile periods and the prepubertal and postpubertal periods of sexual development, respectively. LH and T were measured in blood samples collected before and after GnRH agonist administration. The area under the response curve (AUC) of LH increased progressively in both controls and prenatal T-treated males from 5 to 20 weeks of age (P<0.01). The LH responses in prenatal T-treated males were lower at 20 and 30 weeks of age compared to controls (P<0.05). AUC-T increased progressively in control males from 5 through 30 weeks of age and prenatal T-treated males from 5 to 20 weeks of age. The T response in prenatal T-treated males was higher at 20 weeks compared to controls of same age but similar to controls and prenatal T-treated males at 30 weeks of age (P <0.05). Our findings suggest that prenatal T treatment advances the developmental trajectory of gonadal responsiveness to GnRH in male offspring.     

Effects of ACTH and estradiol on steroid production by cultured adrenal cells from an anencephalic fetus and from normal adults

Dispersed adrenal cells from a 16 1/2 week anencephalic fetus, 7 fetuses with intact pituitaries and 3 adult subjects undergoing renal transplants were maintained in tissue culture and the steroidogenic responses to ACTH (0-10(3) pg/ml), with or without added estradiol (0-10(4) ng/ml) were evaluated. In the anencephalic preparation the response to ACTH was delayed, but by the fifth day production of cortisol, dehydroepiandrosterone (DHA) and DHA-sulfate was similar to that in the other cultured fetal adrenal cells. The addition of estradiol caused dose-related inhibition of cortisol production and concomitant increase in DHA and DHA-sulfate production. The adult adrenal cells in the presence of ACTH showed a much higher cortisol/DHA secretion ratio, but the addition of estradiol markedly reduced this ratio as in fetal cells. The data support the suggestion that the major factors which interact to impose the characteristic fetal pattern of adrenal steroidogenesis are ACTH and the synergistic effects of placental and intra-adrenal steroids (such as estradiol) which act to inhibit 3 beta-hydroxysteroid dehydrogenase activity.