The neuroendocrine response to d-fenfluramine in women with premenstrual depression

Review : Gonadal Steroids and Affective Illness

Gonadal steroids seem to regulate affective state in some people (but not all), despite the absence of abnormal steroid hormone levels or dysfunction of the reproductive endocrine axis. In this article, we attempt to explain this paradox 1) by describing the molecular mechanisms by which gonadal steroids can regulate neuronal function; 2) by describing the specific regulatory impact of gonadal steroids on two systems im plicated in the pathophysiology of mood disorders; and 3) by defining the role of gonadal steroids in several mood disorders linked to periods of reproductive change. We suggest that the context in which the neuro- regulatory actions of gonadal steroids occur determines the impact of steroid signaling on the regulation of affective state. NEUROSCIENTIST 5:227-237, 1999

A lack of consistent evidence for cortisol dysregulation in premenstrual syndrome/premenstrual dysphoric disorder

Although decades of research has examined the association between cortisol regulation and premenstrual syndrome/premenstrual dysphoric disorder (PMS/PMDD), no review exists to provide a general set of conclusions from the extant research. In the present review we summarize and interpret research that has tested for associations between PMS/PMDD and cortisol levels and reactivity (n=38 original research articles). Three types of studies are examined: correlational studies, environmental-challenge studies, and pharmacological-challenge studies. Overall, there was very little evidence that women with and without PMS/PMDD demonstrate systematic and predictable mean-level differences in cortisol, or differences in cortisol response/reactivity to challenges. Methodological differences in sample size, the types of symptoms used for diagnosis (physical and psychological vs. only affective), or the type of cortisol measure used (serum vs. salivary), did not account for differences between studies that did and did not find significant effects. Caution is recommended before accepting the conclusion of null effects, and recommendations are made that more rigorous research be conducted, considering symptom-specificity, within-person analyses, and multiple parameters of cortisol regulation, before final conclusions are drawn.

ACTH and cortisol response to Dex/CRH testing in women with and without premenstrual dysphoria during GnRH agonist-induced hypogonadism and ovarian steroid replacement

CONTEXT

During conditions of ovarian suppression, women with premenstrual dysphoria (PMD) experience abnormal behavioral responses to physiological levels of ovarian steroids. Although hypothalamic-pituitary-adrenal (HPA) axis dysregulation frequently accompanies depression, and ovarian steroids regulate HPA axis responsivity, the role of HPA axis dysregulation in PMD is not known. We hypothesized that women with PMD would show abnormalities of HPA axis function analogous to those reported in depressive illness, and that ovarian steroids would differentially regulate HPA axis function in women with PMD compared with asymptomatic controls (AC).

OBJECTIVE

Our objective was to characterize the HPA axis response to physiological levels of estradiol and progesterone in women with PMD and AC.

DESIGN AND SETTING

We conducted an open-label trial of the GnRH agonist depot Lupron with ovarian steroid replacement administered in a double-blind crossover design in an outpatient clinic.

PARTICIPANTS

Forty-three women (18 with prospectively confirmed PMD and 25 AC) participated.

INTERVENTIONS

Women received Lupron for 6 months. After 3 months of hypogonadism, women received 5 wk each of estradiol (100-μg patch daily) or progesterone (suppositories 200 mg twice daily). During each condition, combined dexamethasone-suppression/CRH-stimulation tests and 24-h urinary free cortisol levels were performed.

MAIN OUTCOME MEASURES

Plasma cortisol and ACTH levels were evaluated.

RESULTS

HPA axis function was similar in PMD compared with AC. In all, progesterone significantly increased the secretion of cortisol compared with estradiol [area under the curve (t(74) = 3.1; P < 0.01)] and urinary free cortisol (t(74) = 3.2; P < 0.01) and ACTH compared with hypogonadism [area under the curve (t(74) = 2.4; P < 0.05)].

CONCLUSIONS

HPA axis regulation is normal in PMD, suggesting that the pathophysiology of PMD differs from major depression. As observed previously, progesterone but not estradiol up-regulates HPA axis function in women.

Fluctuating serotonergic function in premenstrual dysphoric disorder and premenstrual syndrome: findings from neuroendocrine challenge tests

RATIONALE

Premenstrual dysphoric disorder (PMDD) has been assumed to be a subtype of premenstrual syndrome (PMS) with depressive symptoms, such as depressive mood, tension, anxiety, and mood liability during luteal phase. At present, no conclusion has been established about serotonergic function in PMDD.

OBJECTIVE

The purpose of this study was to investigate the serotonergic function of PMDD subjects in comparison to PMS without PMDD subjects and normal controls via neuroendocrine challenge tests.

SUBJECTS AND METHODS

Twenty-four women (seven with PMDD, eight with PMS without PMDD, and nine normal controls) were tested on three occasions (follicular phase, early luteal phase, and late luteal phase) receiving paroxetine 20 mg orally as a serotonergic probe at 8:00 A: .M: . Plasma ACTH and cortisol were measured prior to the administration and every hour for 6 h thereafter.

RESULTS

As a whole, there were significant differences in serotonergic function measured by ACTH and cortisol responses to paroxetine challenge across these three groups. PMDD subjects showed higher serotonergic function in follicular phase but lower serotonergic function in luteal phase, compared with women with PMS without PMDD and normal controls.

CONCLUSION

The present findings suggest that PMDD women have fluctuating serotonergic function across their menstrual cycles and that the pattern may be different from PMS without PMDD.

Tamoxifen fails to affect central serotonergic tone but increases indices of anxiety in female rhesus macaques

The selective estrogen receptor modulator (SERM), tamoxifen, effectively slows the progression of estrogen-positive breast cancer and aids in the prevention of cancer in at-risk women. Tamoxifen is well characterized with regards to its effects on breast cancer, but its effects on other estrogen-related systems, particularly neural circuits regulating brain function and mood, are poorly understood. Using ovariectomized rhesus monkeys, we examined the effects of tamoxifen, with and without estrogen replacement therapy (ERT), on social behavior and central serotonin (5HT) systems thought to influence these behaviors. Relative to placebo treatments, estrogen treatment increased serotonergic tone, based on response in prolactin and cortisol to fenfluramine, a 5HT releasing agent. Tamoxifen neither blocked nor enhanced this effect, indicating it to be neither an antagonist nor an agonist on serotonergic activity. In contrast, CSF measures of the 5HT metabolite, 5HIAA, were not significantly affected by treatment. Tamoxifen-treated animals showed increases in measures of anxiety, compared with ERT-treated animals, suggesting that this SERM may be anxiogenic. Co-treatment with estrogen attenuated the anxiogenic properties of tamoxifen. These data show that tamoxifen administration increased anxiety levels, but the affect was not associated with differences in central levels of the serotonin tone.

Current management of premenstrual syndrome and premenstrual dysphoric disorder

About 5% of women of reproductive age experience affective or physical premenstrual symptoms that markedly influence work, social activities, or relationships. Prospective charting of symptoms for at least two menstrual cycles is required to facilitate an accurate diagnosis of premenstrual syndrome or premenstrual dysphoric disorder. The optimal treatment plan begins with lifestyle modifications, followed by pharmacotherapy. Evidence from numerous controlled trials has clearly demonstrated that low-dose serotonin reuptake inhibitors, using intermittent or continuous administration, have excellent efficacy with minimal side effects. Modification of the menstrual cycle should be considered only after all other treatment options have failed.

The role of central serotonergic dysfunction in the aetiology of premenstrual dysphoric disorder: therapeutic implications

Premenstrual dysphoric disorder (PMDD), as defined in DSM-IV, is a mood disorder. One of the leading theories for the pathogenesis of mood disorders is dysfunction of the serotonergic system. An increasing database suggests that serotonergic dysfunction also characterises PMDD. Evidence that treatments which enhance serotonergic function are beneficial in reducing the symptoms of PMDD support this hypothesis. Indeed, most of the evidence from baseline studies suggests predominantly a serotonergic rather than a noradrenergic or dopaminergic dysfunction. Challenge studies further support this hypothesis. These findings of neurotransmitter dysfunction are more consistent than those of other neuroendocrine abnormalities for example. Based on treatment studies, a selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitor, fluoxetine, has been approved for use in PMDD by the US Food and Drug Administration.

Serotonergic dysfunction in women with pure premenstrual dysphoric disorder: is the fenfluramine challenge test still relevant?

The fenfluramine (FEN) neuroendocrine challenge paradigm, which involves measuring the response of prolactin (PRL) release to an oral challenge dose of FEN, provides a means of assessing serotonin (5-HT) function. The purpose of this study was to ascertain the role of 5-HT in premenstrual dysphoric disorder (PMDD) by measuring: (1) PRL and cortisol (CORT) responses to FEN; and (2) platelet 3H-imipramine binding levels, in females with pure PMDD (without a past or present comorbid mood disorder) in comparison to healthy controls. FEN challenge tests were administered to nine female patients with pure PMDD and nine healthy female controls during the follicular and late luteal phases of a menstrual cycle. There were no differences in the PRL response to FEN for women with PMDD compared to healthy controls. However, the trend toward a delayed response to FEN and a significant negative correlation between delta(max) PRL and basal CORT in patients but not in controls during both phases of the menstrual cycle suggest an underlying 5-HT dysfunction in patients as compared to controls. This is further supported by the finding of significantly lower Bmax 3H-imipramine binding levels in the patients during the late luteal phase.

Selective serotonin reuptake inhibitors and neuroendocrine function

Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are effective drugs for the treatment of several neuropsychiatric disorders associated with reduced serotonergic function. Serotonergic neurons play an important role in the regulation of neuroendocrine function. This review will discuss the acute and chronic effects of SSRIs on neuroendocrine function. Acute administration of SSRIs increases the secretion of several hormones, but chronic treatment with SSRIs does not alter basal blood levels of hormones. However, adaptive changes are induced by long-term treatment with SSRIs in serotonergic, noradrenergic and peptidergic neural function. These adaptive changes, particularly in the function of specific post-synaptic receptor systems, can be examined from altered adrenocorticotrophic hormone (ACTH), cortisol, oxytocin, vasopressin, prolactin, growth hormone (GH) and renin responses to challenges with specific agonists. Neuroendocrine challenge tests both in experimental animals and in humans indicate that chronic SSRIs produce an increase in serotonergic terminal function, accompanied by desensitization of post-synaptic 5-HT1A receptor-mediated ACTH, cortisol, GH and oxytocin responses, and by supersensitivity of post-synaptic 5-HT2A (and/or 5-HT2C) receptor-mediated secretion of hormones. Chronic exposure to SSRIs does not alter the neuroendocrine stress-response and produces inconsistent changes in alpha2 adrenoceptor-mediated GH secretion. Overall, the effects of SSRIs on neuroendocrine function are dependent on adaptive changes in specific neurotransmitter systems that regulate the secretion of specific hormones.

D-Fenfluramine induces serotonin-mediated Fos expression in corticotropin-releasing factor and oxytocin neurons of the hypothalamus, and serotonin-independent Fos expression in enkephalin and neurotensin neurons of the amygdala

The neurotransmitters expressed by neurons activated by D-fenfluramine (5 mg/kg, i.p.) were identified in the hypothalamus, amygdala and bed nucleus of the stria terminalis. Induction of Fos immunoreactivity following D-fenfluramine injection was used as an index of neuronal activation. To test whether D-fenfluramine activated neurons by releasing serotonin from the serotonergic nerve terminals, rats were pretreated with fluoxetine (10 mg/kg, i.p.), a serotonin reuptake inhibitor that prevents the release of serotonin stimulated by D-fenfluramine, 12 h before D-fenfluramine injection. The approximate percentages of peptidergic neurons that contained Fos immunoreactivity after D-fenfluramine administration were 94% of corticotropin-releasing factor and 22% of oxytocin cells in the paraventricular nucleus of the hypothalamus, 6% of oxytocin cells in the supraoptic nucleus of the hypothalamus, 36% of enkephalin and 15% of neurotensin cells in the central amygdaloid nucleus, and 19% of enkephalin and 9% of neurotensin cells in the bed nucleus of the stria terminalis. Fluoxetine pretreatment blocked Fos expression in corticotropin-releasing factor- and oxytocin-expressing cells in the hypothalamus, but not in enkephalin-and neurotensin-expressing cells located in the bed nucleus of the stria terminalis and central amygdaloid nucleus. D-Fenfluramine did not induce Fos immunoreactivity in vasopressin-, thyrotropin-releasing hormone-, somatostatin- and tyrosine hydroxylase-containing cells in the hypothalamus, and corticotropin-releasing factor-expressing cells in the central amygdaloid nucleus and bed nucleus of the stria terminalis. These results show that D-fenfluramine stimulates corticotropin-releasing factor- and oxytocin-expressing cells in the hypothalamus via serotonin release. The enkephalin- and neurotensin-expressing cells in the amygdala are activated by D-fenfluramine via non-serotonergic mechanisms. Induction of Fos expression by D-fenfluramine in restricted populations of cells suggests a selective activation of neuronal circuitry that is likely to be involved in the appetite suppressant effects of D-fenfluramine.

Estrogen-serotonin interactions: implications for affective regulation

A burgeoning literature documents the convergence of reproductive endocrine and central serotonergic systems in the regulation of a variety of behaviors. This review will focus on one element of this interaction, the modulation of serotonergic function by estrogen. After describing the manifold neuroregulatory effects of gonadal steroids, we summarize the effects of estrogen on central serotonin systems in animals and humans as inferred from studies demonstrating the impact of gender, estrus (or menstrual) cycle, or hormone manipulation. Finally, we summarize the putative roles of estrogen and serotonin in two reproductive-endocrine-related mood disorders: premenstrual syndrome and perimenopausal depression.

The 5-HT1A and 5-HT2A/2C receptor antagonists WAY-100635 and ritanserin do not attenuate D-fenfluramine-induced fos expression in the brain

D-Fenfluramine is a serotonin (5-hydroxytryptamine, 5-HT) releaser and reuptake inhibitor. It is used to study the neurochemical control of feeding and has been used to treat obesity. It has also been employed as a pharmacological tool to study changes in serotonergic function in psychiatric patients. Brain sites activated by D-fenfluramine via the release of 5-HT have been mapped via the expression of the immediate early gene c-fos. Studies in our laboratory have indicated that D-fenfluramine induces Fos in the hypothalamus and cortex through 5-HT release. The present study investigated whether 5-HT released by D-fenfluramine induces Fos expression in the brain by activating 5-HT1A or 5-HT2A/2C receptors. Rats were pretreated either with WAY-100635, a 5-HT1A antagonist, or ritanserin, a 5-HT2A/2C antagonist, prior to d-fenfluramine injection. Blockade of either 5-HT1A or 5-HT2A/2C receptors was not sufficient to suppress the Fos response to D-fenfluramine in any region of the brain examined, including the cingulate cortex, frontal cortex, caudate-putamen, paraventricular nucleus of the hypothalamus, amygdala, and brainstem. These results indicate that Fos response elicited by D-fenfluramine may be mediated by other receptors, in addition to the 5-HT1A or 5-HT2A/2C receptors.

Premenstrual syndromes

Premenstrual syndrome research has made a great deal of progress since 1983 when the criteria for the diagnosis were clearly defined. Confirming the diagnosis prospectively and ruling out other disorders was a major methodologic advance. The DSM-IV criteria for PMDD now help us identify and classify women who have severe psychologic symptoms during the premenstruum. Although we do not have a definitive cause for PMDD, the consensus is that it is the end result of a complex series of events mediated partly by the serotonin system and triggered by ovulation. Women who meet criteria for PMS, do not meet the criteria for PMDD, and do not have a concurrent disorder should be treated conservatively. Women who meet criteria for PMDD can be treated successfully with low-dose clomipramine, SSRIs, or GnRH-as with "add back" estrogen and progestins.

Serotonin re-uptake inhibitors in the treatment of premenstrual dysphoria: Current state of knowledge

Late luteal phase dysphoric disorder (LLPDD) and the more recently introduced premenstrual dysphoric disorder (PMDD) are recognized psychiatric disorders that consist of distressing emotional and behavioural symptoms that occur premenstrually. Recently, advances have been made in understanding the aetiology of the disorder, with clear evidence to implicate the serotonergic system. In women with predominately psychological symptoms, selective serotonin re-uptake inhibitors (SSRIs), as well as clomipramine, have demonstrated excellent efficacy and minimal side effects.

Diagnosis and treatment of premenstrual dysphoric disorder

Premenstrual syndrome (PMS) is a common problem and patients with PMS are encountered by obstetricians, gynecologists, family practitioners, internists (general physicians) and psychiatrists. Despite several decades of biological research, the etiology of the disorder is still elusive. The introduction of a psychiatric category called premenstrual dysphoric disorder (PMDD), describing women with severe emotional premenstrual symptoms, has advanced biological treatment research by identifying a more homogeneous patient population. This paper aims to review our current understanding of the clinical presentation, underlying psycho-biology, and essentials of treatment for premenstrual dysphoric disorder.