Sex differences in corticosteroid binding in the rat brain: an in vitro autoradiographic study

Hippocampus diffusivity abnormalities in classical trigeminal neuralgia

Introduction

Patients with chronic pain frequently report cognitive symptoms that affect memory and attention, which are functions attributed to the hippocampus. Trigeminal neuralgia (TN) is a chronic neuropathic pain disorder characterized by paroxysmal attacks of unilateral orofacial pain. Given the stereotypical nature of TN pain and lack of negative symptoms including sensory loss, TN provides a unique model to investigate the hippocampal implications of chronic pain. Recent evidence demonstrated that TN is associated with macrostructural hippocampal abnormalities indicated by reduced subfield volumes; however, there is a paucity in our understanding of hippocampal microstructural abnormalities associated with TN.

Objectives

To explore diffusivity metrics within the hippocampus, along with its functional and structural subfields, in patients with TN.

Methods

To examine hippocampal microstructure, we utilized diffusion tensor imaging in 31 patients with TN and 21 controls. T1-weighted magnetic resonance images were segmented into hippocampal subfields and registered into diffusion-weighted imaging space. Fractional anisotropy (FA) and mean diffusivity were extracted for hippocampal subfields and longitudinal axis segmentations.

Results

Patients with TN demonstrated reduced FA in bilateral whole hippocampi and hippocampal body and contralateral subregions CA2/3 and CA4, indicating microstructural hippocampal abnormalities. Notably, patients with TN showed significant correlation between age and hippocampal FA, while controls did not exhibit this correlation. These effects were driven chiefly by female patients with TN.

Conclusion

This study demonstrates that TN is associated with microstructural hippocampal abnormalities, which may precede and potentially be temporally linked to volumetric hippocampal alterations demonstrated previously. These findings provide further evidence for the role of the hippocampus in chronic pain and suggest the potential for targeted interventions to mitigate cognitive symptoms in patients with chronic pain.

The influence of sex difference on behavior and adult hippocampal neurogenesis in C57BL/6 mice

Animal models have been used extensively in in vivo studies, especially within the biomedical field. Traditionally, single-sex studies, mostly males, are used to avoid any potential confounding variation caused by sex difference and the female estrous cycle. Historically, female animal subjects are believed to exhibit higher variability, and this could increase the statistical power needed to test a hypothesis. This study sets out to evaluate whether a sex difference does exist in mouse behavior, and whether female mice featured higher variability. We assessed the sensorimotor skills, anxiety-like behavior, depression-like behavior, and cognitive abilities of mice through a series of commonly used behavioral tests. Except for the stronger grip force and lower tactile sensory sensitivity detected in male mice, there was no significant difference between males and females in other tests. Furthermore, immunolabeling of neurogenesis markers suggested no significant difference between sexes in adult hippocampal neurogenesis. Within group variances were equivalent; females did not exhibit higher variability than males. However, the overall negative results could be due to the limitation of small sample size. In conclusion, our study provides evidence that sex difference in mice does not significantly influence these commonly used behavioral tests nor adult neurogenesis under basal conditions. We suggest that female mice could also be considered for test inclusion in future experiment design.

Aging, Social Distancing, and COVID-19 Risk: Who is more Vulnerable and Why?

Perceived social support represents an important predictor of healthy aging. The global COVID-19 pandemic has dramatically changed the face of social relationships and revealed elderly to be particularly vulnerable to the effects of social isolation. Social distancing may represent a double-edged sword for older adults, protecting them against COVID-19 infection while also sacrificing personal interaction and attention at a critical time. Here, we consider the moderating role of social relationships as a potential influence on stress resilience, allostatic load, and vulnerability to infection and adverse health outcomes in the elderly population. Understanding the mechanisms how social support enhances resilience to stress and promotes mental and physical health into old age will enable new preventive strategies. Targeted social interventions may provide effective relief from the impact of COVID-19-related isolation and loneliness. In this regard, a pandemic may also offer a window of opportunity for raising awareness and mobilizing resources for new strategies that help build resilience in our aging population and future generations.

HIV-1 Tat Protein Promotes Neuroendocrine Dysfunction Concurrent with the Potentiation of Oxycodone's Psychomotor Effects in Female Mice

Human immunodeficiency virus (HIV) is associated with neuroendocrine dysfunction which may contribute to co-morbid stress-sensitive disorders. The hypothalamic-pituitary-adrenal (HPA) or -gonadal (HPG) axes are perturbed in up to 50% of HIV patients. The mechanisms are not known, but we have found the HIV-1 trans-activator of transcription (Tat) protein to recapitulate the clinical phenotype in male mice. We hypothesized that HPA and/or HPG dysregulation contributes to Tat-mediated interactions with oxycodone, an opioid often prescribed to HIV patients, in females. Female mice that conditionally-expressed the Tat_1-86 protein [Tat(+) mice] or their counterparts that did not [Tat(-) control mice] were exposed to forced swim stress (or not) and behaviorally-assessed for motor and anxiety-like behavior. Some mice had glucocorticoid receptors (GR) or corticotropin-releasing factor receptors (CRF-R) pharmacologically inhibited. Some mice were ovariectomized (OVX). As seen previously in males, Tat elevated basal corticosterone levels and potentiated oxycodone's psychomotor activity in females. Unlike males, females did not demonstrate adrenal insufficiency and oxycodone potentiation was not regulated by GRs or CRF-Rs. Rather OVX attenuated Tat/oxycodone interactions. Either Tat or oxycodone increased anxiety-like behavior and their combination increased hypothalamic allopregnanolone. OVX increased basal hypothalamic allopregnanolone and obviated Tat or oxycodone-mediated fluctuations. Together, these data provide further evidence for Tat-mediated dysregulation of the HPA axis and reveal the importance of HPG axis regulation in females. HPA/HPG disruption may contribute vulnerability to affective and substance use disorders.

Chronic adolescent stress causes sustained impairment of cognitive flexibility and hippocampal synaptic strength in female rats

Females that experience chronic stress during development, particularly adolescence, are the most vulnerable group to stress-induced disease. While considerable attention has been devoted to stress-induced manifestation of anxiety, depression, and PTSD, evidence indicates that a history of chronic stress is also a risk factor for cognitive decline and dementia - with females again in a higher risk group. This interplay between sex and stress history indicates specific mechanisms drive neural dysfunction across the lifespan. The presence of sex and stress steroid receptors in the hippocampus provides a point of influence for these variables to drive changes in cognitive function. Here, we used a rodent model of chronic adolescent stress (CAS) to determine the extent to which CAS modifies glutamatergic signaling resulting in cognitive dysfunction. Male and female Wistar rats born in-house remained non-stressed (NS), unmanipulated aside from standard cage cleaning, or were exposed to either physical restraint (60 min) or social defeat (CAS) each day (6 trials each), along with social isolation, throughout the adolescent period (PND 35-47). Cognition was assessed in adult (PND 80-130) male and female rats (n = 10-12) using the Barnes Maze task and the Attention Set-Shift task. Whole hippocampi were extracted from a second cohort of male and female rats (NS and CAS; n = 9-10) and processed for RNA sequencing. Brain tissue from the first cohort (n = 6) was processed for density of glutamatergic synaptic markers (GluA1, NMDA1a, and synaptophysin) or whole-cell patch clamping (n = 4) to determine glutamatergic activity in the hippocampus. Females with a history of chronic stress had shorter latencies to locate the goal box than NS controls during acquisition learning but showed an increased latency to locate the new goal box during reversal learning. This reversal deficit persisted across domains as females with a history of stress required more trials to reach criterion during the reversal phases of the Attention Set-Shift task compared to controls. Ovariectomy resulted in greater performance variability overall during reversal learning with CAS females showing worse performance. Males showed no effects of CAS history on learning or memory performance. Bioinformatic prediction using gene ontology categorization indicated that in females, postsynaptic membrane gene clusters, specifically genes related to glutamatergic synapse remodeling, were enriched with a history of stress. Structural analysis indicated that CAS did not alter glutamate receptor density in females. However, functionally, CAS females had a decreased AMPA/NMDA-dependent current ratio compared to controls indicating a weakening in synaptic strength in the hippocampus. Males showed only a slight change in density of NMDA1a labeling in the CA3 region with a history of stress. The data observed here suggest that females are at risk for impaired cognitive flexibility following a history of adolescent stress, possibly driven by changes in glutamatergic signaling.

Sex differences in the hypothalamic-pituitary-adrenal axis' response to stress: an important role for gonadal hormones

The hypothalamic-pituitary-adrenal (HPA) axis, a neuroendocrine network that controls hormonal responses to internal and external challenges in an organism's environment, exhibits strikingly sex-biased activity. In adult female rodents, acute HPA function following a stressor is markedly greater than it is in males, and this difference has largely been attributed to modulation by the gonadal hormones testosterone and estradiol. These gonadal hormones are produced by the hypothalamic-pituitary-gonadal (HPG) axis and have been shown to determine sex differences in adult HPA function after acute stress via their activational and organizational effects. Although these actions of gonadal hormones are well supported, the possibility that sex chromosomes similarly influence HPA activity is unexplored. Moreover, questions remain regarding sex differences in the activity of the HPA axis following chronic stress and the underlying contributions of gonadal hormones and sex chromosomes. The present review examines what is currently known about sex differences in the neuroendocrine response to stress, as well as outstanding questions regarding this sex bias. Although it primarily focuses on the rodent literature, a brief discussion of sex differences in the human HPA axis is also included.

Sex differences in the HPA axis

The hypothalamic-pituitary-adrenal (HPA) axis is a major component of the systems that respond to stress, by coordinating the neuroendocrine and autonomic responses. Tightly controlled regulation of HPA responses is critical for maintaining mental and physical health, as hyper- and hypo-activity have been linked to disease states. A long history of research has revealed sex differences in numerous components of the HPA stress system and its responses, which may partially form the basis for sex disparities in disease development. Despite this, many studies use male subjects exclusively, while fewer reports involve females or provide direct sex comparisons. The purpose of this article is to present sex comparisons in the functional and molecular aspects of the HPA axis, through various phases of activity, including basal, acute stress, and chronic stress conditions. The HPA axis in females initiates more rapidly and produces a greater output of stress hormones. This review focuses on the interactions between the gonadal hormone system and the HPA axis as the key mediators of these sex differences, whereby androgens increase and estrogens decrease HPA activity in adulthood. In addition to the effects of gonadal hormones on the adult response, morphological impacts of hormone exposure during development are also involved in mediating sex differences. Additional systems impinging on the HPA axis that contribute to sex differences include the monoamine neurotransmitters norepinephrine and serotonin. Diverse signals originating from the brain and periphery are integrated to determine the level of HPA axis activity, and these signals are, in many cases, sex-specific.

Chronic scream sound exposure alters memory and monoamine levels in female rat brain

Chronic scream sound alters the cognitive performance of male rats and their brain monoamine levels, these stress-induced alterations are sexually dimorphic. To determine the effects of sound stress on female rats, we examined their serum corticosterone levels and their adrenal, splenic, and thymic weights, their cognitive performance and the levels of monoamine neurotransmitters and their metabolites in the brain. Adult female Sprague-Dawley rats, with and without exposure to scream sound (4h/day for 21 day) were tested for spatial learning and memory using a Morris water maze. Stress decreased serum corticosterone levels, as well as splenic and adrenal weight. It also impaired spatial memory but did not affect the learning ability. Monoamines and metabolites were measured in the prefrontal cortex (PFC), striatum, hypothalamus, and hippocampus. The dopamine (DA) levels in the PFC decreased but the homovanillic acid/DA ratio increased. The decreased DA and the increased 5-hydroxyindoleacetic acid (5-HIAA) levels were observed in the striatum. Only the 5-HIAA level increased in the hypothalamus. In the hippocampus, stress did not affect the levels of monoamines and metabolites. The results suggest that scream sound stress influences most physiologic parameters, memory, and the levels of monoamine neurotransmitter and their metabolites in female rats.

Treatment of dexamethasone-induced hiccup in chemotherapy patients by methylprednisolone rotation

Dexamethasone-induced hiccup (DIH) is an underrecognized symptom in patients with cancer, and little information is available about its treatment. The aims of this study were to investigate the feasibility of methylprednisolone rotation as treatment and to confirm the male predominance among those with cancer who experienced DIH during chemotherapy. Methods. Persons with cancer who experienced hiccups during chemotherapy treatment and who were receiving treatment with dexamethasone were presumed to have DIH. The following algorithmic practice was implemented for antiemetic corticosteroid use: rotation from dexamethasone to methylprednisolone in the next cycle and dexamethasone re-administration in the second cycle of chemotherapy after recognition of hiccups to confirm DIH. All other antiemetics except corticosteroid remained unchanged. Patients (n = 40) were recruited from eight cancer centers in Korea from September 2012 to April 2013. Data were collected retrospectively. Results. Hiccup intensity (numeric rating scale [NRS]: 5.38 vs. 0.53) and duration (68.44 minutes vs. 1.79 minutes) were significantly decreased after rotation to methylprednisolone, while intensity of emesis was not increased (NRS: 2.63 vs. 2.08). Median dose of dexamethasone and methylprednisolone were 10 mg and 50 mg, respectively. Thirty-four (85%) of 40 patients showed complete resolution of hiccups after methylprednisolone rotation in the next cycle. Of these 34 patients, 25 (73.5%) had recurrence of hiccups after dexamethasone re-administration. Compared with baseline values, hiccup intensity (NRS: 5.24 vs. 2.44) and duration (66.43 minutes vs. 22.00 minutes) were significantly attenuated after dexamethasone re-administration. Of the 40 eligible patients, 38 (95%) were male. Conclusion. DIH during chemotherapy could be controlled without losing antiemetic potential by replacing dexamethasone with methylprednisolone. We also identified a male predominance of DIH. Further prospective studies are warranted.

Long-term imipramine treatment affects rat brain and pituitary corticosteroid receptors and heat shock proteins levels in a gender-specific manner

Gender-related differences in the effects of imipramine, on the protein levels of glucocorticoid receptor (GR), and heat shock proteins Hsp90 and Hsp70, as well as on dexamethasone binding to corticosteroid receptors (CRs) in the pituitary, hypothalamus, hippocampus and brain cortex of non-depressed rats were studied. Differences between female and male animals in the GR protein level in the tissues of untreated animals were not noticed. However, imipramine led to opposite changes in the cellular level of GR protein in the brain of female and male rats, as well as to gender- and tissue-specific changes in in vitro dexamethasone binding to GR and mineralocorticoid receptor (MR) in the hippocampus and brain cortex. Gender-related differences in the expression of Hsp90 and Hsp70 were noticed mainly in the hippocampus, only after imipramine treatment. The observed changes in the response of GR to imipramine suggest that this antidepressant may affect both the level of the receptor protein and the mechanisms regulating its binding ability in a gender-related manner.

Acute stress impairs spatial memory in male but not female rats: influence of estrous cycle

We investigated how sex and estrous cycle influenced spatial recognition memory in the Y-maze after exposure to acute restraint stress. In Experiment 1, intact male and female rats were restrained for 1 h and then 2 h after the start of restraint, rats were trained on the Y-maze. After a 4 h delay, hippocampal-dependent spatial recognition memory was assessed. Acute stress produced opposite patterns between the sexes with spatial memory being impaired in males and facilitated in females. Serum corticosterone measures indicated that both sexes showed a robust corticosterone response after restraint and a moderate corticosterone response after Y-maze exposure. Serum corticosterone levels in response to restraint and Y-maze were not statistically different between the sexes. Experiment 2 examined the influence of the estrous cycle on spatial memory ability after acute stress. Acute stress facilitated spatial memory in females compared to controls, regardless of the estrous cycle phase (estrus and proestrus). Moreover, females in proestrus showed higher serum corticosterone levels during restraint compared to females in estrus. No differences in corticosterone levels were observed at baseline or following 2 h of recovery from restraint. These data show important differences in how sex and estrous cycle influence cognitive functions following acute stress.

Hormonal status modifies renin-angiotensin system-regulating aminopeptidases and vasopressin-degrading activity in the hypothalamus-pituitary-adrenal axis of male mice

Local renin-angiotensin systems (RAS) have been postulated in brain, pituitary and adrenal glands. These local RAS have been implicated, respectively, in the central regulation of the cardiovascular system and body water balance, the secretion of pituitary hormones and the secretion of aldosterone by adrenal glands. By other hand, it is known that the hypothalamus-pituitary-adrenal (HPA) axis is involved in blood pressure regulation, and is affected by sex hormones. The aim of the present work is to analyze the influence of testosterone on RAS-regulating aminopeptidase A, B and M activities and vasopressin-degrading activity in the HPA axis, measuring these activities in their soluble and membrane-bound forms in the hypothalamus, pituitary and adrenal glands of orchidectomized males and orchidectomized males treated subcutaneously with several doses of testosterone. The present data suggest that in male mice, testosterone influences the RAS- and vasopressin-degrading activities at all levels of the HPA axis.

Chronic stress effects on memory: sex differences in performance and monoaminergic activity

Increasing evidence suggests that the time course of advantageous versus deleterious effects of stress on physiologic function is also apparent in some brain functions, including learning and memory. This article reviews the effects of chronic stress on behavioral performance and, more importantly, shows that sex of the subject, as well as duration and intensity of stress, is an important determinant of the functional/behavioral, neurochemical, and anatomical consequences of the stress. Following chronic stress (7-28 days of restraint, 6 h/day), male and female rats were tested on a visual memory task (object recognition) and two spatial memory tasks (object placement and radial arm maze). At 21 days, stress impaired males on all tasks while females were either enhanced (spatial memory tasks) or not impaired (nonspatial memory tasks). Additionally, the influence of the hypothalamic-pituitary-adrenocortical axis in mediating the sex-specific responses to stress is considered. Behavioral and neurochemical assessments following chronic stress in ovariectomized females, with and without estradiol, suggest that estrogen exerts both organizational and activational influences on the observed sex differences in response to stress. Furthermore, stress differentially affected central transmitter levels in the frontal cortex, hippocampus, and amygdala depending on sex. The possible role of these sex-specific changes in neurotransmitter levels in mediating behavioral differences in response to stress is discussed. While these results are thus far limited to a few studies and require both further investigation and verification, chronic stress appears to be associated with distinct, sex-differentiated behavioral/cognitive and neurochemical responses. We conclude that sex differences must be taken into account when investigating or describing stress and associated sequalae.

Functional cross-talk between the hypothalamic-pituitary-gonadal and -adrenal axes

Under normal conditions, the adrenal glucocorticoids, the endproduct of the hypothalamic-pituitary-adrenal (HPA) axis, provide a frontline of defence against threats to homeostasis (i.e. stress). On the other hand, chronic HPA drive and glucocorticoid hypersecretion have been implicated in the pathogenesis of several forms of systemic, neurodegenerative and affective disorders. The HPA axis is subject to gonadal influence, indicated by sex differences in basal and stress HPA function and neuropathologies associated with HPA dysfunction. Functional cross-talk between the gonadal and adrenal axes is due in large part to the interactive effects of sex steroids and glucocorticoids, explaining perhaps why several disease states linked to stress are sex-dependent. Realizing the interactive nature by which the hypothalamic-pituitary-gonadal and HPA systems operate, however, has made it difficult to model how these hormones act in the brain. Manipulation of one endocrine system is not without effects on the other. Simultaneous manipulation and assessment of both endocrine systems can overcome this problem. This dual approach in the male rat reveals that testosterone can act and interact on different aspects of basal and stress HPA function. Basal adrenocorticotropic hormone (ACTH) release is regulated by testosterone-dependent effects on arginine vasopressin synthesis, and corticosterone-dependent effects on corticotropin-releasing hormone (CRH) synthesis in the paraventricular nucleus (PVN) of the hypothalamus. In contrast, testosterone and corticosterone interact on stress-induced ACTH release and drive to the PVN motor neurones. Candidate structures mediating this interaction include several testosterone-sensitive afferents to the HPA axis, including the medial preoptic area, central and medial amygdala and bed nuclei of the stria terminalis. All of these relay homeostatic information and integrate reproductive and social behaviour. Because these modalities are affected by stress in humans, a dual systems approach holds great promise in establishing further links between the neuroendocrinology of stress and the central bases of sex-dependent disorders, including psychiatric, cardiovascular and metabolic disease.

Steroid hormones affect limbic afterdischarge thresholds and kindling rates in adult female rats

Catamenial epileptics show particular vulnerability to seizures during menstruation and at the time of ovulation, when circulating estradiol (E(2))/progesterone (P(4)) ratios are high. The present study tested the hypothesis that alterations in neuronal excitability induced by E(2) and P(4) affect thresholds and the development of secondary generalization in kindled rats.

METHODS

The effects of endogenous hormones secreted during the estrous cycle, and of exogenous exposure to E(2) and P(4) after ovariectomy (OVX), with and without adrenalectomy (ADX), were tested. Kindling electrodes were implanted in the basolateral amygdala or dorsal hippocampus in adult female rats. The anticonvulsive effects of P(4) on amygdala kindled seizures were also determined in intact subjects.

RESULTS

In intact females, afterdischarge thresholds (ADTs) in the amygdala were significantly lower (306+/-48 microA; peak to peak) at mid-day proestrus, just prior to ovulation, when serum E(2) is elevated. ADTs were more than twofold higher (808+/-95 microA) during metestrus, coincident with peak ovarian P(4) secretion. In OVX females, amygdala thresholds were lowest with E(2) replacement and highest with P(4) replacement. Hippocampal ADT was unaffected by hormone replacement after OVX. The rates of both amygdala and hippocampal kindling were significantly accelerated by E(2) and slowed by P(4). E(2) replacement significantly increased serum corticosterone (CORT) levels. In ADX rats, CORT replacement increased kindling rates, synergizing with the effects of E(2). In fully kindled animals, P(4) administration suppressed motor seizures in approximately 60% of cases.

CONCLUSIONS

E(2) lowers amygdala ADTs and facilitates kindling. This effect may involve both direct E(2) effects and indirect effects mediated via increased levels of circulating corticosterone. P(4) raises amygdala ADTs, slows kindling development and suppresses fully kindled seizures. Hence, P(4) may have potential therapeutic value for women with catamenial epilepsy.

Hormonal interactions in the effects of halogenated aromatic hydrocarbons on the developing brain

Halogenated arylhydrocarbons (HAHs) exert a wide range of effects on the developing brain. These effects result in altered patterns of neuroendocrine function and behavior in adulthood, as well as changes in cognitive function. The underlying mechanisms have not yet been clearly defined. This paper briefly reviews the effects of HAHs on brain development, and proposes the hypothesis that interactions between different hormone-sensitive systems may contribute to the broad spectrum of responses observed after fetal or early postnatal HAH exposure. Physiological interactions between the effects of sex steroids, corticosteroids, and thyroid hormone are known to influence the development of the central nervous system (CNS). Since the biosynthesis and/or action of each of these hormones is sensitive to developmental HAH exposure, it is suggested that convergent effects of HAHs on different endocrine pathways may underlie some of the disruptive effects of these chemicals on CNS differentiation. Data are presented indicating that the disruptive effects of low dose dioxin exposure on sexual differentiation of the rat brain are probably not mediated through blockade of estrogen responses, but may instead involve subtle developmental changes in other endocrine systems, perhaps also affecting the feedback control of adrenocortical function. The potential for interactive endocrine effects illustrates the need for a fuller understanding of the range of biological activities of HAHs in the brain, so that the potential risks of low dose developmental exposure to these environmental toxicants can be predicted with greater certainty.

Sex differences in pain-induced effects on the septo-hippocampal system

In addition to its role in the modulation of functions such as arousal and attention, learning and memory, the limbic system has repeatedly been described to be involved in the regulation of several behavioral aspects concerning the adaptation to aversive situations, including pain. A key role in these processes seems to be played by the septo-hippocampal system. This paper, far from being a comprehensive review of all the data available about the limbic system, describes some of the circuits participating in the septo-hippocampal system, with the aim of contributing to an understanding of the sex differences in the behavioral, hormonal and neuronal responses to aversive stimuli. It will appear that the complex anatomical and functional interactions between the different neurotransmitters acting at this level prevent one from indicating a certain substance as more important than others in determining a difference between the two sexes. This leads to the conclusion that the septo-hippocampal formation in toto plays a key role in determining the sex differences in the 'pain experience'.

Influence of gonadal steroids on brain corticosteroid receptors: a minireview

Sex differences exist in the functioning of the two brain corticosteroid receptor systems. Ovarian steroid replacement alters receptor mRNA expression, receptor binding capacities, and receptor affinity. The abundance of both mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) message can be reduced by estrogen. Progesterone is able to partially antagonize the action of estrogen and to induce MR transcription. The effect of estrogen on receptor binding capacity is more modest than its transcriptional actions. Estrogen decreases MR binding more reliably than it does GR. Progesterone has high affinity for the MR and can substantially reduce MR affinity for corticoids. Androgen apparently regulates corticoid receptor transcription but may not affect binding capacity. Estrogen and androgen are both more potent in regulating pituitary-adrenal function than would be suggested by their actions on receptor binding parameters.