ACTH In Rats Research Articles

Maternal separation and TNBS-induced gut inflammation synergistically alter the sexually differentiated stress response in rats

BackgroundNeonatal maternal separation (MS) has been used to model long-lasting changes in behavior caused by neuroplastic changes associated with exposure to early-life stress. Earlier studies showed that transient gut inflammation can influence the development of irritable bowel syndrome (IBS). A prevailing paradigm of the etiology of IBS is that transient noxious events lead to long-lasting sensitization of the neural pain circuit, despite complete resolution of the initiating event. This study characterizes the changes in behaviors and neuroendocrine parameters after MS and early-phase trinitrobenzene sulfonic acid (TNBS)-induced colitis. We tested the hypothesis that MS and gut inflammation synergistically induce (1) hyperactivity in male rats and anxiety-like behaviors in female rats and (2) activation of the HPA axis in female rats and deactivation of the HPA axis in male rats after colorectal distention (CRD).MethodsMale and female rat pups were separated from their dams for 180 min daily from postnatal day (PND) 2 to PND 14 (MS). Early-phase colitis was induced by colorectal administration with TNBS on PND 8. The elevated plus-maze test was performed at 7 weeks. Tonic CRD was performed at 60 mmHg for 15 min at 8 weeks. Plasma ACTH and serum corticosterone were measured at baseline or after the CRD. Analysis of variance was performed for comparison among controls, TNBS, MS, and MS + TNBS.ResultsIn male rats, the time spent in open arms significantly differed among the groups (p < 0.005). The time spent in open arms in male MS + TNBS rats was significantly higher than that of controls (p < 0.009) or TNBS rats (p < 0.031, post hoc test). Female rats showed no difference in the time spent in open arms among the groups. MS and gut inflammation induced an increase in plasma ACTH in female rats but not in male rats at baseline.ConclusionsThese findings suggest that MS and gut inflammation synergistically induce hyperactive behavior or exaggerated hypothalamic–pituitary–adrenal axis function depending on sex.

ACTON PROLONGATUM® suppresses spasms head to head with Acthar® Gel in the model of infantile spasms

Epileptic spasms during infancy (infantile spasms, IS) are a rare epilepsy syndrome with dire prognosis. Current treatments, effective in about 55% of cases, include hormonal therapy (adrenocorticotropic hormone [ACTH] = adrenocorticotropin or corticosteroids) or vigabatrin (also in combination with hormones). In addition to their limited efficacy, these treatments may also carry serious adverse effects. Thus, the search for new effective drugs to treat this rare disease is desirable. In this study, we determined the efficacy of ACTON PROLONGATUM® (AP; Ferring Pharmaceuticals) in comparison with Acthar® Gel (Mallinckrodt) and full 39 amino-acid rat ACTH molecule (Genscript) in the rodent model of IS consisting of prenatal priming with betamethasone and repeated postnatal trigger of spasms with N-methyl-d-aspartate. Treatment with these ACTH varieties was given on postnatal days (P)12, P13, and P14 in a prospective test (treatment onset on P12 AFTER induction of spasms). Two independent arms were investigated: subcutaneous (SC) and intramuscular (IM) deliveries that were evaluated separately. In the SC arm, there was a significant suppression of the number of spasms after both Acthar® Gel and AP on P13 and P15 compared with gelatin control. In the IM arm, a significant suppression of the number of spasms was achieved only after AP on both P13 and P15 indicating that after IM delivery, Acthar® Gel was not as effective as AP. In this study, we confirmed the efficacy of two ACTH formulations (gelatin-based Acthar® Gel and carboxymethyl cellulose-based AP) in the model of IS. ACTON PROLONGATUM® may become a valuable therapy for IS. In our animal model, AP was at least as efficient as the standard of care, Acthar® Gel.

AQB-565 shows promise in preclinical testing in the model of epileptic spasms during infancy: Head-to-head comparison with ACTH

Epileptic spasms during infancy (infantile spasms) represent a serious treatment and social problem despite their rare occurrence. Current treatments include hormonal therapy (adrenocorticotropin-ACTH or corticosteroids) or vigabatrin (per se or in the combination). These treatments are partially effective and with potentially significant adverse effects. Thus, the search for new effective drugs is warranted. We tested efficacy of a novel fusion peptide AQB-565 developed by Aequus Biopharma in a model of infantile spasms consisting of prenatal exposure to betamethasone and repeated postnatal trigger of spasms with N-methyl-d-aspartic acid (NMDA). AQB-565 molecule includes the first 24 amino acids of ACTH, a ten amino acid linker and a modified melanocyte-stimulating hormone molecule. In contrast to ACTH with almost uniform activity over all peripheral and central melanocortin receptor isoforms, AQB is preferentially active on central melanocortin receptors MC3 and MC4. Here, we used equivalent doses of rat ACTH (full molecule) and AQB-565 and compared their efficacy in a prospective randomized test against of repeated bouts of spasms on postnatal days (P)12, P13 and P15 in the rat model. All doses of ACTH (range 0.02–1.0 mg/kg s.c.) and all doses but one of AQB-565 in the same range suppressed spasms in P15 rats (treatment stopped on P14). There was no dose-dependent effect and both compounds had all-or-none effect that is similar to clinical outcome of hormonal treatment of infantile spasms in children. Thus, AQB-565 may represent a novel treatment of infantile spasms similarly effective as ACTH but with potentially limited side effects.

Identification of Bioactive Chemical Markers in Zhi zhu xiang Improving Anxiety in Rat by Fingerprint-Efficacy Study.

Zhi zhu xiang (ZZX for short) is the root and rhizome of Valeriana jatamansi Jones, which is a Traditional Chinese Medicine (TCM) used to treat various mood disorders for more than 2000 years, especially anxiety. The aim of the present work was to identify the bioactive chemical markers in Zhi zhu xiang improving anxiety in rats by a fingerprint-efficacy study. More specifically, the chemical fingerprint of ZZX samples collected from 10 different regions was determined by High Performance Liquid Chromatography (HPLC) and the similarity analyses were calculated based on 10 common characteristic peaks. The anti-anxiety effect of ZZX on empty bottle stimulated rats was examined through the Open Field Test (OFT) and the Elevated Plus Maze Test (EPM). Then we measured the concentration of CRF, ACTH, and CORT in rat’s plasma by the enzyme-linked immune sorbent assay (ELISA) kit, while the concentration of monoamine and metabolites (NE, DA, DOPAC, HVA, 5-HT, 5-HIAA) in the rat’s cerebral cortex and hippocampus was analysed by HPLC coupled with an Electrochemical Detector. At last, the fingerprint-efficacy study between chemical fingerprint and anti-anxiety effect of ZZX was accomplished by partial least squares regression (PLSR). As a result, we screened out four compounds (hesperidin, isochlorogenic acid A, isochlorogenic acid B and isochlorogenic acid C) as the bioactive chemical markers for the anti-anxiety effect of ZZX. The fingerprint-efficacy study we established might provide a feasible way and some elicitation for the identification of the bioactive chemical markers for TCM.

Palatable Food Affects HPA Axis Responsivity and Forebrain Neurocircuitry in an Estrous Cycle-specific Manner in Female Rats

Eating palatable foods can provide stress relief, but the mechanisms by which this occurs are unclear. We previously characterized a limited sucrose intake (LSI) paradigm in which twice-daily access to a small amount of 30% sucrose (vs. water as a control) reduces hypothalamic–pituitary–adrenocortical (HPA) axis responses to stress and alters neuronal activation in stress-regulatory brain regions in male rats. However, women may be more prone to ‘comfort feeding’ behaviors than men, and stress-related eating may vary across the menstrual cycle. This suggests that LSI effects may be sex- and estrous cycle-dependent. The present study therefore investigated the effects of LSI on HPA axis stress responsivity, as well as markers of neuronal activation/plasticity in stress- and reward-related neurocircuitry in female rats across the estrous cycle. We found that LSI reduced post-restraint stress plasma ACTH in female rats specifically during proestrus/estrus (P/E). LSI also increased basal (non-stress) FosB/deltaFosB- and pCREB-immunolabeling in the basolateral amygdala (BLA) and central amygdala specifically during P/E. Finally, Bayesian network modeling of the FosB/deltaFosB and pCREB expression data identified a neurocircuit that includes the BLA, nucleus accumbens, prefrontal cortex, and bed nucleus of the stria terminalis as likely being modified by LSI during P/E. When considered in the context of our prior results, the present findings suggest that palatable food reduces stress responses in female rats similar to males, but in an estrous cycle-dependent manner. Further, the BLA may contribute to the LSI effects in both sexes, whereas the involvement of other brain regions appears to be sex-dependent.

YL-0919, a dual 5-HT1A partial agonist and SSRI, produces antidepressant- and anxiolytic-like effects in rats subjected to chronic unpredictable stress.

YL-0919 has been identified as a novel dual 5-HT1A partial agonist and serotonin reuptake inhibitor. In the current study, we demonstrated that YL-0919 produced prominent antidepressant-like and anxiolytic-like effects in a chronic unpredictable stress (CUS) rat model. Male SD rats were exposed to CUS for 5 weeks; YL-0919 (1.25 and 2.5 mg/kg) or a positive control fluoxetine (Flx, 10 mg/kg) was orally administered daily. YL-0919 or Flx treatment significantly increased the sucrose preference rate, the locomotor activity in an open field test (OFT), the latency to feed in a novelty-suppressed feeding test (NSFT), and both the percentage of time spent in the open arms and the number of entries into the open arms in an elevated plus-maze test. YL-0919 or Flx treatment significantly suppressed the serum levels of ACTH and corticosterone in CUS-exposed rats. Additionally, YL-0919 or Flx treatment significantly enhanced the levels of cAMP, the expression of phosphorylated cAMP response element-binding protein (pCREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus of CUS-exposed rats. Similar to Flx, YL-0919 treatment significantly enhanced the dendritic complexity, and increased the number of dendritic nodes as well as the spine length and number of branch nodes in the hippocampal pyramidal neurons of CUS-exposed rats. Overall, our results reveal that YL-0919 suppresses the HPA axis and exerts antidepressant-like and anxiolytic-like effects in CUS-exposed rats, which are associated with the enhanced cAMP signaling and hippocampal dendritic complexity.

Maternal separation during nursing alters basal neuroendocrine levels in juvenile and adult rats.

Work with different animal models including that of maternal separation during nursing has shown that early adverse experiences such as abuse, maternal abandonment and psychosocial stress may favor the development of various psychopathologies. However, several neuroendocrine changes have not been completely described yet. To establish whether maternal separation during nursing modifies the basal levels of neurohormones such as corticosterone, ACTH, oxytocin and vasopressin in juvenile and adult rats (aged 35 and 90 days, respectively). Wistar rats were separated from their mothers for two periods of 3 hours per day during the 21 days of nursing. Once these rats had reached 35 and then 90 days of age, blood samples were taken from both the separated and control groups to obtain serum for immunoenzymatic assays and measure the levels of each of the hormones. Concentrations of corticosterone were higher in control adult females in comparison with the rest of the groups and lower in the control adult males. Those of ACTH were higher in the separated young males and females than in the adult groups. Oxytocin levels were significantly higher in the separated adult females in comparison with the other groups and significantly lower in the adult males. With respect to vasopressin, the separated groups had lower concentrations than the young and adult control groups. These results show that the early stress to which rats were submitted produced changes in the basal responses of the hypothalamic-pituitary-adrenal axis, that these responses were distinct in males and females and that they also differed according to age.

The Defecation Index as a Measure of Emotionality: Questions Raised by HPA Axis and Prolactin Response to Stress in the Maudsley Model.

The Maudsley Reactive and Maudsley Non-Reactive strains have been selectively bred for differences in open-field defecation (OFD), a putative index of stress. We investigated whether variations in the hypothalamic-pituitary-adrenal (HPA) axis are correlated with strain differences in OFD in the Maudsley model. Exposure to the open-field test did not result in increases in ACTH in male rats of either strain and there were no strain differences in the large increases in ACTH and corticosteroid that occurred in response to intermittent footshock. Parallel studies of prolactin showed that Maudsley Reactive rats had greater response to the open-field and to footshock than Maudsley Non-Reactive rats. The lack of correlation between strain differences in OFD and reactivity of the HPA axis is consistent with the idea that HPA response to stress and OFD reflect the output of different neural systems and that individual differences in emotionality, as indexed by OFD do not influence other measures of stress-reactivity in a simple manner, if at all. The reactivity of the prolactin system to the open-field test and lack of response of ACTH to the same situation is consistent with the idea that the prolactin system is sensitive to lower levels of stress than the HPA axis, a finding at variance with the presumed extreme sensitivity of the latter system. Earlier comparisons of the HPA axis in these strains implicate local factors such as neuropeptide-Y peptide in the adrenal in attenuating the response of the adrenal cortex to ACTH and hints at the complexity of regulation of the HPA axis.

Effect of Noise and Crowding Related Stress on Serum Level of Cortisol ACTH , Epinephrine and Insulin in Female Albino Rats

Background: Noise and crowding are the most stressful factors for human beings. Study aimed to clarify their effect on cortisol, ACTH, epinephrine, insulin and the amelioration effect of Sulpiride. Material and Methods: Thirty six female rats were divided into six groups (6/each): 1- Rats served as control, 2- Rats treated with Sulpiride drug, 3- Rats exposed to noise (90db, 3hr. per day) for 45 days. 4- Rats exposed to noise and treated with sulpiride drug, 5- Rats exposed to crowding. 6- Rats exposed to noise and treated with Sulpiride drug. Results: Noise and crowding stresses caused a significant increase of cortisol, ACTH and epinephrine while there was a significant decrease in insulin hormone. Sulpiride drug ameliorated these parameters. Conclusion: it is useful to use Sulpiride drug with people who are exposing to noise and crowding

The influence of poststress social factors on hormonal reactivity in prepubertal male rats

Following a variety of stressors, prepubertal animals display significantly longer hormonal stress responses than adults. Although the mechanisms that mediate this pubertal-related difference in stress reactivity are unclear, previous studies have shown that social interactions are differentially affected by stress in animals before and after puberty. Given the influence of social factors on stress reactivity, we hypothesize the protracted stress-induced hormonal response in prepubertal animals may be in part mediated by aspects of their poststress social environment. We explored this hypothesis by measuring plasma ACTH and corticosterone in prepubertal male rats 15, 30, and 45 min after a 30 min session of restraint stress exposed to one of three social conditions: recovering in the presence of a stressed cage mate; recovering in the presence of a nonstressed cage mate; and recovering in the absence of a cage mate. We report here that although prepubertal and adult animals display different hormonal responses following restraint, the presence or absence of stressed cage mates has little impact on the poststress hormonal response in prepubertal males. We do, however, show that social factors can alter HPA reactivity in prepubertal animals, in that significant hormonal responses are evoked in nonstressed animals exposed to a stressed cage mate, an effect not found in adults. Collectively, these data indicate that although the poststress social environment does not play a role in mediating the protracted hormonal response in prepubertal animals, the social context can significantly influence HPA activation in otherwise unstressed animals prior to puberty.

The influence of heroin withdrawal and relapse on pituitary ACTH, beta‐EP cells and serum cortisol level in rats

To investigate the effect of heroin withdrawal and relapse on the morphology and function of pituitary ACTH, β‐EP cells and the serum cortisol level and to further explore the possible mechanism. 63 adult male SD rats were randomly divided into normal control group (NCG), saline control group (SCG), and experiment group(EG). The rats in EG group were sub‐divided into heroin withdrawal group (HWG), methadone detoxication group (MDG), and heroin relapse group (HRG). The pituitary of rats was excised soon after the serum was obtained via heart puncture. The morphology of pituitary ACTH, β‐EP cells was observed by using immunohistochemical SABC method, image analysis, and transmission electron microscopy (TEM). RIA was used to detect the serum cortisol level. The immunostaining intensity of ACTH cells in HWG and HRG was higher and β‐EP cells was lower when compared with NCG and SCG. TEM showed that vacuolation, dilatation of endoplasmic reticulum, secretory granules decreased, smaller irregular nucleus, and the increased perinuclear space occurred in the ACTH cells in HWG and HRG. The results of RIA showed that the level of serum cortisol in each group of EG was significantly increased as compared with NCG (P&lt;0.05). The results suggest that the pituitary‐adrenal axis is activated and the secretion of endogenous opioid peptides is inhibited during heroin withdrawal and relapse period.

Sensitization of restraint-induced corticosterone secretion after chronic restraint in rats: Involvement of 5-HT7 receptors

Serotonin (5-HT) modulates the hypothalamic-pituitary-adrenal (HPA) axis response to stress. We examined the effect of chronic restraint stress (CRS; 20 min/day) as compared to control (CTRL) conditions for 14 days, on: 1) restraint-induced ACTH and corticosterone (CORT) secretion in rats pretreated with vehicle or SB-656104 (a 5-HT7 receptor antagonist); 2) 5-HT7 receptor-like immunoreactivity (5-HT7-LI) and protein in the hypothalamic paraventricular nucleus (PVN) and adrenal glands (AG); 3) baseline levels of 5-HT and 5-hydroxyindolacetic acid (5-HIAA), and 5-HIAA/5-HT ratio in PVN and AG; and 4) 5-HT-like immunoreactivity (5-HT-LI) in AG and tryptophan hydroxylase (TPH) protein in PVN and AG. On day 15, animals were subdivided into Treatment and No treatment groups. Treatment animals received an i.p. injection of vehicle or SB-656104; No Treatment animals received no injection. Sixty min later, Treatment animals were either decapitated with no further stress (0 min) or submitted to acute restraint (10, 30, 60 or 120 min); hormone serum levels were measured. No Treatment animals were employed for the rest of measurements. CRS decreased body weight gain and increased adrenal weight. In CTRL animals, acute restraint increased ACTH and CORT secretion in a time of restraint-dependent manner; both responses were inhibited by SB-656104. Exposure to CRS abolished ACTH but magnified CORT responses to restraint as compared to CTRL conditions; SB-656104 had no effect on ACTH levels but significantly inhibited sensitized CORT responses. In CTRL animals, 5-HT7-LI was detected in magnocellular and parvocellular subdivisions of PVN and sparsely in adrenal cortex. Exposure to CRS decreased 5-HT7-LI and protein in the PVN, but increased 5-HT7-LI in the adrenal cortex and protein in whole AG. Higher 5-HT and 5-HIAA levels were detected in PVN and AG from CRS animals but 5-HIAA/5-HT ratio increased in AG only. Finally, whereas 5-HT-LI was sparsely observed in the adrenal cortex of CTRL animals, it strongly increased in the adrenal cortex of CRS animals. No TPH protein was detected in AG from both animal groups. Results suggest that CRS promotes endocrine disruption involving decreased ACTH and sensitized CORT responses to acute restraint. This phenomenon may be associated with increased function and expression of 5-HT7 receptors as well as 5-HT turnover in AG.

Effects of Electroacupuncture at Auricular Concha Region on the Depressive Status of Unpredictable Chronic Mild Stress Rat Models

To explore new noninvasive treatment options for depression, this study investigated the effects of electroacupuncture (EA) at the auricular concha region (ACR) of depression rat models. Depression in rats was induced by unpredictable chronic mild stress (UCMS) combined with isolation for 21 days. Eighty male Wistar rats were randomly assigned into four groups: normal, UCMS alone, UCMS with EA-ACR treatment, and UCMS with EA-ear-tip treatment. Rats under inhaled anesthesia were treated once daily for 14 days. The results showed that blood pressure and heart rate were significantly reduced in the EA-ACR group than in the UCMS alone group or the EA-ear-tip group. The open-field test scores significantly decreased in the UCMS alone and EA-ear-tip groups but not in the EA-ACR group. Both EA treatments downregulated levels of plasma cortisol and ACTH in UCMS rats back to normal levels. The present study suggested that EA-ACR can elicit similar cardioinhibitory effects as vagus nerve stimulation (VNS), and EA-ACR significantly antagonized UCMS-induced depressive status in UCMS rats. The antidepressant effect of EA-ACR is possibly mediated via the normalization of the hypothalamic-pituitary-adrenal (HPA) axis hyperactivity.

Constant light disrupts the circadian rhythm of steroidogenic proteins in the rat adrenal gland

The circadian rhythm of corticosterone (CORT) secretion from the adrenal cortex is regulated by the suprachiasmatic nucleus (SCN), which is entrained to the light–dark cycle. Since the circadian CORT rhythm is associated with circadian expression of the steroidogenic acute regulatory (StAR) protein, we investigated the 24h pattern of hormonal secretion (ACTH and CORT), steroidogenic gene expression (StAR, SF-1, DAX1 and Nurr77) and the expression of genes involved in ACTH signalling (MC2R and MRAP) in rats entrained to a normal light–dark cycle. We found that circadian changes in ACTH and CORT were associated with the circadian expression of all gene targets; with SF-1, Nurr77 and MRAP peaking in the evening, and DAX1 and MC2R peaking in the morning. Since disruption of normal SCN activity by exposure to constant light abolishes the circadian rhythm of CORT in the rat, we also investigated whether the AM–PM variation of our target genes was also disrupted in rats exposed to constant light conditions for 5weeks. We found that the disruption of the AM–PM variation of ACTH and CORT secretion in rats exposed to constant light was accompanied by a loss of AM–PM variation in StAR, SF-1 and DAX1, and a reversed AM–PM variation in Nurr77, MC2R and MRAP. Our data suggest that circadian expression of StAR is regulated by the circadian expression of nuclear receptors and proteins involved in both ACTH signalling and StAR transcription. We propose that ACTH regulates the secretion of CORT via the circadian control of steroidogenic gene pathways that become dysregulated under the influence of constant light.

P.1.f.004 Behavioural and neurodevelopmental effects of ACTH and glucocorticoids in neonatal rats

This chapter highlights how studies of the giant dopamine neuron (GDN) located in the left pedal ganglion of the pond snail Planorbis corneus have provided direct demonstration of reverse transport from a neuron in real time. The GDN is advantageous for these studies because it has nomifensine-sensitive plasma membrane dopamine (DA) uptake, reserpine-sensitive vesicular DA uptake, it metabolizes DA to dihydroxyphenylacetic acid, and lacks ascorbic acid, facilitating the unambiguous amperometric detection of DA. Exocytic quantal release events can easily be distinguished from release by reverse transport using carbon fiber electrodes. The large size of the neuron allows the estimation of cytosolic levels of DA with intracellular carbon electrodes. The large size of the cell, the presence of the DA uptake system, and presence of many synaptic vesicles provides an enormous transmitter pool, proving the means to detect reverse transport from a single cell.

Congenital absence of vasopressin and age-dependent changes in ACTH and corticosterone stress responses in rats

The hypothalamic components of the hypothalamo–pituitary–adrenal axis (HPA) are corticotropin-releasing hormone (CRH) and vasopressin. To test the hypothesis that HPA regulation changes with age, we compared ether and bacterial lipopolysaccharide (LPS) injection induced stress reactions in adult and 10-day-old Brattleboro rats, which naturally lack vasopressin owing to mutation of the gene (di/di). The LPS stimulus was used also with V1b receptor antagonist pretreatment (SSR149415). In adult di/di or V1b pretreated rats, we observed normal pituitary and adrenocortical secretory responses, while in all 10-day-old rats stress-induced serum corticosterone increases were marked, but adrenocorticotropin (ACTH) increases were significantly smaller. Compared to control pups the adenohypophysis of the 10-day-old di/di rats responded normally to CRH, but their adrenal glands were hyper-responsive to ACTH, while in adults there was greater secretion at both levels with no difference between the genotypes. The serum transcortin level was higher in adults than pups, with the di/di pups having higher transcortin levels than controls. Hence, using the same stressors in adults and pups with both a genetic model and pharmacological pretreatment, we have shown that the role of vasopressin in ACTH regulation is more important during the neonatal period than in adulthood. Blunted hypophysial sensitivity to CRH and similar adrenal gland sensitivity to ACTH in the pups compared to adults suggest that hypothalamic factors could be responsible for the neonatal stress hyporesponsive period.

Effect of Animal Facility Construction on Basal Hypothalamic-Pituitary-Adrenal and Renin-Aldosterone Activity in the Rat

Although loud noise and intense vibration are known to alter the behavior and phenotype of laboratory animals, little is known about the effects of nearby construction. We studied the effect of a nearby construction project on the classic stress hormones ACTH, corticosterone, renin, and aldosterone in rats residing in a barrier animal facility before, for the first 3 months of a construction project, and at 1 month after all construction was completed. During some of the construction, noise and vibrations were not obvious to investigators inside the animal rooms. Body weight matched for age was not altered by nearby construction. During nearby construction, plasma ACTH, corticosterone, and aldosterone were approximately doubled compared with those of pre- and postconstruction levels. Expression of CRH mRNA in the paraventricular nucleus of the hypothalamus, CRH receptor and POMC mRNA in the anterior pituitary, and most mRNAs for steroidogenic genes in the adrenal gland were not significantly changed during construction. We conclude that nearby construction can cause a stress response without long-term effects on hypothalamic-pituitary-adrenal axis gene expression and body weight.

Changes of Dipeptidyl Peptidase (DP IV) Activity in the T Lymphocytes of Rats Following Administration of ACTH, Dexamethasone and Opiates

The aim of the work was to study the effect of glucocorticoids, opiates and stressful stimuli on dipeptidyl peptidase IV (DP IV, EC 3.4.14.5) activity of T lymphocytes prepared from the thymus of intact and adrenalectomized rats. Four week old male rats of Wistar strain were used. The in vivo administration of ACTH, dexamethasone and morphine treatment resulted in an increase of DP IV activity in the cell suspension. In adrenalectomized rats ACTH treatment failed to modify the enzyme activity, however, pain or emotional stress resulted in an elevated DP IV activity. Morphine and D-Met2-Pro5-enkephalinamide resulted in a dose dependent activation of DP IV in T cells, an effect which could be modified by naloxone pretreatment. Our findings show that DP IV mechanisms in T cells are highly sensitive to exogenous and endogenous steroids, opiates and biologically active substances released in response to stress in rats.

Different mechanisms mediate the in vivo aldosterone and corticosterone responses to 5-bromo-2'-deoxyuridine in rats.

The subcutaneous injection of 5'-bromo-2' deoxyuridine (BrdU) was found to raise the plasma concentrations of ACTH, aldosterone and corticosterone in rats. The aldosterone response was observed at a lower dose of BrdU and lasted for a longer period than those of ACTH and corticosterone (1.25 versus 2.50 mg/100 g body weight; 48 versus 24 h). Corticosterone response to BrdU was partially reversed by the ACTH-receptor antagonist corticotropin-inhibiting peptide (CIP), and aldosterone response by the arginine vasopressin (AVP) V1-receptor antagonist [amino-Pen1, Val4,D-Arg8]-vasopressin (AVP-A). The angiotensin-II (ANG-II)-receptor antagonist [Sar1, Val5, Ala8]-ANG-II (SAR) was ineffective. CIP, AVP-A and SAR, when administered alone, did not alter basal levels of ACTH, aldosterone and corticosterone. In light of these findings the following conclusions can be drawn: (i) BrdU stimulates the hypothalamo-pituitary-adrenal axis in rats, and this effect may influence the results of cell-kinetics studies carried out with the BrdU-labelling technique, especially in those tissue that are highly responsive to glucocorticoids (e.g. pituitary, adrenal and lymphatic tissues); and (ii) different mechanisms underlie the aldosterone and corticosterone secretagogue effects of BrdU, the former being at least in part dependent on the stimulation of AVP release and the latter on the rise in ACTH secretion.

Genistein affects the morphology of pituitary ACTH cells and decreases circulating levels of ACTH and corticosterone in middle-aged male rats.

The soybean phytoestrogen, genistein, is increasingly consumed as an alternative therapeutic for age-related diseases, namely cardiovascular conditions, cancer and osteoporosis. However, despite the beneficial effects on health, concern has been raised that this isoflavone also acts as an endocrine-disrupting chemical. The aim of this study was to examine the effects of genistein on immunohistomorphometric features of pituitary adrenocorticotropic cells (ACTH) and blood concentrations of ACTH and corticosterone in orchidectomized middle-aged male rats. Sixteen-month-old Wistar rats were divided into sham-operated (SO), orchidectomized (Orx) and genistein-treated orchidectomized (Orx+G) groups. Genistein (30mg/kg/day) was administered subcutaneously for three weeks, while the control groups received the vehicle alone. ACTH cells were identified by the peroxidase-antiperoxidase (PAP) immunohistochemical procedure. Circulating concentrations of ACTH and corticosterone were measured by immunoassay. Orchidectomy reduced (p<0.05) the cell volume and the relative volume of ACTH cells in comparison to SO rats. Genistein treatment further decreased (p<0.05) these morphometric parameters and reduced (p<0.05) circulating ACTH and corticosterone concentrations by more than 20% in comparison to both Orx and SO rats. In conclusión, genistein modulated the immunohistomorphometric features of ACTH cells and decreased blood ACTH and corticosterone levels, which supports evidence that this isoflavone affects the hypothalamic-pituitary-adrenal axis and suppresses glucocorticoid hormone secretion.