Thyrotropin, prolactin, and growth hormone responses to thyrotropin-releasing hormone in anorexia nervosa and bulimia

TRH in the nucleus accumbens acts downstream to α-MSH to decrease food intake in rats

Feeding-regulatory peptides such as thyrotropin-releasing hormone (TRH), α-melanocyte-stimulating hormone (α-MSH) and their receptors are expressed in brain regions involved in the homeostatic and hedonic control of food intake, such as the hypothalamus and the mesolimbic system, respectively. The nucleus accumbens (NAc) is part of the latter, a brain circuit involved in processing reward stimuli and the appetitive motivation of feeding. When TRH or α-MSH are administered in the NAc, both decrease food intake, through activating their respective receptors, TRH-R1 and MC4R. The actions of α-MSH as a homeostatic feeding-regulator involves the increase of hypothalamic TRH expression, thus, we aimed to identify whether TRH signaling in the NAc was also participating in α-MSH-induced reduction of food intake. α-MSH administration in the NAc of 48 h fasted rats reduced their food intake during the 2-h period of refeeding, increased accumbal TRH mRNA expression and decreased that of MC4R. Such downregulated MC4R mRNA levels implied a compensatory decrease of α-MSH actions in the NAc after the previous pathway stimulation. The co-administration of α-MSH along with an antisense oligonucleotide directed against pro-TRH mRNA in the NAc impaired the α-MSH-induced feeding reduction, supporting that the accumbal TRHergic pathway is downstream of α-MSH actions to inhibit feeding. Our results suggested that TRH in the NAc mediates some effects of α-MSH on inhibition of food intake; this supports the role of TRH not only as a homeostatic regulator but also as modulating the motivational aspects of feeding.

Growth hormone and insulin-like growth factor 1 secretions in eating disorders: Correlations with psychopathological aspects of the disorders

Hormonal alterations in Eating Disorders (ED) may result from the biochemical stress of malnutrition/starvation. The correlations between some hormonal impairments, particularly of the somatotropic axis, and the psychopathological aspects of ED are still undefined. We measured the plasma concentrations of the somatotropic hormone (GH) and the insulin-like growth factor-1 (IGF-1) in 136 patients with various forms of ED, 65 with restricted Anorexia Nervosa (ANR), 19 with bingeing-purging Anorexia Nervosa (ANBP), 12 with purging-non binging Anorexia Nervosa (ANP), 26 with Bulimia Nervosa (BN), 8 with ED not otherwise specified-anorexic type (EDNOS-AN), 7 with ED not otherwise specified-bulimic type (EDNOS-BN) and in 30 healthy controls. Psychological assessment of patients and controls was performed using two outpatient rating scales, the Eating Disorder Inventory-2 (EDI-2) and the Symptom Checklist-90 (SCL-90). Significant negative or positive correlations were observed between GH-IGF-1 concentrations and impairments on several EDI-2 subscales (drive for thinness, body dissatisfaction, interoceptive awareness, sense of ineffectiveness, interpersonal distrust, maturity fear) and on SCL-90 subitems (depression, hostility, obsessivity compulsivity, anxiety), suggesting a possible hormonal modulatory effect on specific aspects of ED psychopathology.

Pharmacotherapy and medical complications of eating disorders in children and adolescents

In this article, the authors cover two areas of interest regarding eating disorders in childhood and adolescence: (1) the detection of eating disorders in medical practice and their medical complications and (2) the psychopharmacologic treatment of patients with eating disorders.

Update on endocrine disturbances in anorexia nervosa

The marked endocrine changes that occur in anorexia nervosa have aroused a great deal of interest, and over the last decade much research has been conducted in this field. The endocrine disturbances are not specific to this disorder, as they also occur in starvation states secondary to other causes, and they return to normal upon weight restoration. However, emaciation may have profound effects on psychological processes, establishing an intricate circular interaction whereby somatic and psychological manifestations of starvation may continue to act. The purpose of this paper is to provide an overview of the large body of literature concerning endocrine aspects of anorexia nervosa with the main focus on the latest results, which provide leads for potential etiological theories.

Evidence of diffuse atrophy of the thyroid gland in patients with anorexia nervosa

OBJECTIVE

The altered function of the hypothalamic-pituitary-thyroid axis (HPT) in anorexia nervosa (AN) patients has not been clearly elucidated so far. Low triiodothyronine (T3) syndrome and a blunted and delayed thyrotropin (TSH) response to exogenously administrated thyrotropin-releasing hormone (TRH) are common findings. However, no attention has been paid to thyroid morphology in AN patients.

METHOD

We performed an ultrasonographic (US) evaluation of the thyroid gland in 22 AN patients and in 44 age and sex-matched control subjects. Lean body mass (LBM) was determined by dual-energy X-ray absorptiometry.

RESULTS

US-determined thyroid volume was significantly reduced in AN patients (9.2 +/- 0.4 vs. 17.8 +/- 1.2 ml in the controls; M +/- SEM; p < 10(-4)). In healthy subjects, it has previously been established that thyroid volume can be estimated from age and body weight. In the present study, the measured thyroid volume in patients with AN was significantly lower than the predicted thyroid volume (measured: 9.2 +/- 0.4 vs. estimated: 12.2 +/- 0.2 ml; p < 10(-4)). Furthermore, in the AN patients, the thyroid size was not correlated to body mass index (BMI) or LBM.

DISCUSSION

Thyroid volume in AN patients was markedly reduced compared with the control group and with the volume expected from age and body weight or LBM. This indicates thyroid atrophy, which, hypothetically, could be involved in a vicious circle maintaining anorectic or depressive symptomatology.

A review of endocrine changes in anorexia nervosa

Anorexia nervosa is a syndrome of unknown etiology. It is associated with multiple endocrine abnormalities. Hypothalamic monoamines (especially serotonin), neuropeptides (especially neuropeptide Y and cholecystokinin) and leptin are involved in the regulation of human appetite, and in several ways they are changed in anorexia nervosa. However, it remains to be clarified whether the altered appetite regulation is secondary or etiologic. Increased secretion of corticotropin-releasing hormone and proopiomelanocortin seems to be secondary to starvation, however, there is evidence that it may maintain and intensify anorexia, excessive physical activity and amenorrhea. Hypothalamic amenorrhea, which is a diagnostic criterion in anorexia nervosa, is not solely related to the low body weight and exercise. Growth hormone resistance with low production of insulin-like growth factor I and high growth hormone secretion reflect the nutritional deprivation. The nutritional therapy of patients with anorexia nervosa might be improved by administering an anabolic agent such as growth hormone or insulin-like growth factor I. So far none of the endocrine abnormalities have proved to be primary, however, there is increasing evidence that some of these might participate in a vicious circle.

Are young women in Japan at high risk for eating disorders?: Decreased BMI in young females from 1960 to 1995

The height, weight and body mass index (BMI) of Japanese males and females aged from 6 to 24 years between 1960 and 1995 were studied. From 1960 to 1995 in males of all ages and in females aged 6-14 years height, weight and BMI increased. In females aged 15-24 years, the height increased and the weight slightly increased, but the BMI gradually decreased from 21.5 in 1960 to 20.5 in 1995. Over the last 35 years adolescent and young adult women have become thinner. Dieting to be slim has become much more prevalent among young women. These findings suggest that young females in Japan have decreased their BMI by dieting in order to become slim. If this tendency persists, with regard to a close relationship between restrained eating or dieting and eating disorders, Japanese young women have a much greater risk of developing eating disorders.

Prolactin response to d-fenfluramine is blunted in people with anorexia nervosa

BACKGROUND

Several studies have explored serotonin (5-HT) transmission in people with anorexia nervosa, but their results have been inconsistent.

METHOD

According to a double-blind placebo-controlled design, plasma prolactin response to the specific serotonergic probed d-fenfluramine was investigated in 10 under weight and two normal-weight women with anorexia, and in 12 age-matched healthy females. Eating-related psychopathology, depressive and obsessive--compulsive symptoms, and aggressiveness were measured by appropriate rating scales.

RESULTS

Compared with healthy control subjects, the women with anorexia showed reduced baseline prolactin and oestrogen levels and increased basal cortisol concentrations. The prolactin response to d-fenfluramine was blunted and did not correlate with psychopathological measures.

CONCLUSIONS

These results support a dysfunction of 5-HT transmission in anorexia nervosa. This dysfunction does not seem to be related to concomitant depressive or obsessive--compulsive symptoms or to the level of aggressiveness of the patients.

Hexarelin is a stronger GH-releasing peptide than GHRH in normal cycling women but not in anorexia nervosa

Anorexia nervosa (AN) is a chronic disease in which an enhanced GH response to GHRH, a paradoxic increase after TRH and LHRH, and low IGF1 levels may be present according to the patient's clinical state. It is well known that the GH hypersecretory state commonly found in the "acute phase" of AN is restored with weight gain. The new synthetic hexapeptide, Hexarelin (HEX), which is chemically similar to GH-releasing peptide 6, has recently been shown to possess a stronger GH-releasing activity than GHRH in humans and to share a synergistic effect with GHRH when administered intravenously. Indeed, HEX shows a slight cortisol and PRL-releasing activity. The aim of the study was to evaluate the effect of i.v. administration of old (GHRH) and new (HEX) GH-releasing peptides on GH, PRL and cortisol secretion in 9 AN patients in the "recovery phase" of the disease, after partial but significant weight gain. For controls we studied 7 normal cycling women. No significant difference in GH secretion after GHRH was found between AN and controls. GHRH was not able to release cortisol or PRL either in AN or controls. HEX produced a significantly (p < 0.05) higher GH peak in controls than in AN, while GH AUC was slightly but not significantly higher. Indeed, only in controls, HEX was a stronger GH-releasing peptide than GHRH. These findings could be explained by the fact that, in AN, GH secretion is already stimulated both by reduced IGF1 levels and by increased GHRH/somatostatin ratio. As reported in the literature, the action of HEX action is only slightly influenced by variations in somatostatin tone. It therefore appears likely that the absolute or relative GHRH increase present in AN could partially mimic the unknown hypothalamic factor necessary for HEX action on the hypophisis and that, following a structural modification of pituitary HEX receptors, GHRH would become able to bind to HEX receptors on somatotropic cells. Consequently, the pituitary cells would already be over-activated and so unable to respond maximally to HEX stimulation. Indeed, in AN, GHRH might play a role of negative modulation in the control of HEX action. Finally, in our study HEX was able to produce a persistent PRL release in controls but not in AN, thus suggesting that its action could be partially dependent on the estrogen milieu, while it stimulated cortisol secretion only transiently in the patients studied.

Circadian patterns of cortisol, prolactin, and growth hormonal secretion during bingeing and vomiting in normal weight bulimic patients

Women who are of normal weight and have bulimia nervosa exhibit multiple neuroendocrine disturbances. We hypothesized that bingeing and vomiting behavior could be contributory because food consumption in healthy volunteers increases plasma cortisol and prolactin secretion and suppresses growth hormone secretion. Thus, we investigated the effects of bingeing and vomiting on the circadian pattern (measurements every 20 min for 24 hr) of these hormones in comparison to healthy control women eating normally. Bingeing and vomiting were associated with modest increases in cortisol and prolactin and reductions in growth hormone secretion. However, this bingeing or purging did not alter mean 24-hr pattern of cortisol and growth hormone secretion as values for bulimics were similar to controls. While mean daytime patterns of prolactin secretion were similar in bulimics and controls, bulimic patients had a significant reduction of nocturnal prolactin levels. In summary, bingeing and vomiting does not appear to have a substantial influence on hormonal secretion. However, bulimic women have blunted nocturnal prolactin patterns.

Blockade of cholinergic muscarinic receptors by pirenzepine and GHRH-induced GH secretion in the acute and recovery phase of anorexia nervosa and atypical eating disorders

In view of the important role played by the cholinergic system in the neural regulation of growth hormone (GH) secretion, the ability of pirenzepine, a selective antagonist of muscarinic cholinergic receptors, to blunt the GH response to GH-releasing hormone (GHRH) was studied in adolescent females with anorexia nervosa in the acute (AN-AP) five AN-AP patients, administration of GHRH 1-40 (1 microgram/kg IV) evoked a significantly higher GH response than in controls at established intervals, whereas in eight AN-RP and seven AED patients it was higher than in controls at only one (150-min) and two (150-min, 180-min) time intervals, respectively. In the AN-AP patients, pretreatment with pirenzepine (0.6 mg/kg IV) only partially blocked the GH response to GHRH, whereas in the same AN-AP patients tested during recovery, and in AN-RP and AED patients, the drug completely suppressed the GH response to GHRH, as it did in controls. In view of pirenzepine's mechanism of action, these findings are best explained by the existence in the hypothalamus of AN-AP patients of a cholinergic hypertone and/or a diminished somatostatinergic function. Evaluation of the clinical and hormonal characteristics of the anorectic patients studied would indicate that factors other than undernutrition and its biological consequences, which subside in the recovery stage of the disease and are not present in AED patients, contribute to the anomalous GH response pattern of AN-AP patients.

Triiodothyronine administration reduces serum growth hormone levels and growth hormone responses to thyrotropin-releasing hormone in patients with anorexia nervosa

The aim of this study was to test the hypothesis that low serum T3 concentrations may promote an abnormal growth hormone (GH) response to thyrotropin-releasing hormone (TRH) in patients with anorexia nervosa. Eight anorexic women and two anorexic men, ages 15-25 years, with low free T3 circulating levels (mean +/- SEM = 2.8 +/- 0.3 pmol/l) were studied. A TRH test (200 micrograms IV) was carried out under basal conditions and repeated following treatment with oral T3 (1.5 micrograms/kg BW/day) for eight days. Following T3 administration, GH levels dropped significantly from a baseline of 7.1 +/- 1.3 micrograms/l to 3.1 +/- 0.7 micrograms/l (p less than 0.02), as did GH peak responses to TRH (9.0 +/- 1.0 micrograms/l vs 4.4 +/- 0.8 micrograms/l, p less than 0.01). ANOVA and analysis of area under the curve (AUC) confirmed that after T3 treatment there was a significant reduction in TRH-induced GH release in these patients (GH AUC: 902 +/- 132 micrograms/l vs. 456 +/- 91 micrograms/l, p less than 0.02). TSH responses to TRH, which were normal prior to T3 treatment, completely disappeared following it, and PRL responses to TRH also were diminished. Although our experimental approach does not permit a conclusion that low T3 levels were the primary reason for these changes, the data support the theory that low T3 circulating levels may facilitate abnormal GH secretion and the GH-releasing activity of intravenous TRH.

The effect of bingeing and vomiting on hormonal secretion

Women who are of normal weight and have bulimia nervosa have multiple neuroendocrine disturbances. The reasons for these neuroendocrine abnormalities are not known, but there are reasons to suspect that bingeing and vomiting behavior could be contributory. It is well known that food consumption in healthy volunteers increases plasma insulin, cortisol, and prolactin secretion and suppresses growth hormone secretion, whereas activation of the emetic reflex increases plasma arginine vasopressin (AVP) secretion. The purpose of this study was to investigate the effects of bingeing and vomiting on these hormones. In comparison with healthy control women consuming a large meal, bulimic patients, when bingeing and vomiting, had an exaggerated secretion of either the amount and/or the duration of insulin, cortisol, and prolactin. Vasopressin secretion was not increased during or after bingeing and vomiting, probably because bulimic subjects do not become nauseated. In addition, bulimic patients had significantly reduced baseline plasma prolactin and possibly elevated baseline cortisol compared with controls. In summary, this study supports the presence of neuroendocrine disturbances in bulimia and raises a question as to whether or not excessive and prolonged food consumption (and/or vomiting) are contributory.

The DST and TRH test in bulimia nervosa

Abnormal neuroendocrine responses have been found in depression and eating disorders. It remains unclear whether these reflect an underlying shared biology or epiphenomena. To evaluate this further, we conducted the 1 mg DST and the TSH response to 500 micrograms i.v. TRH in normal-weight bulimics and controls. Bulimics (n = 18) demonstrated significantly more DST non-suppression (45%) than controls (18%; n = 20). In the bulimic group, non-suppressors were significantly thinner than suppressors, but did not differ from them on any measure of depression. Bulimics (n = 19) and controls (n = 12) responded similarly without blunting on the TSH response to TRH. These data suggest that DST non-suppression may be related to non-specific variables such as weight. Bulimics do not demonstrate TSH blunting as found in some depressed patients. These tests do not support evidence for a biological link between these disorders.

Neuroendocrine profile in bulimia nervosa

The neuroendocrinology of bulimia nervosa has only recently been investigated, with initial research suggesting some biological overlap with both anorexia nervosa (AN) and depression. Similarities among AN, depression, and bulimia include a nonsuppressed Dexamethasone Suppression Test and an abnormal growth hormone (GH) response to thyrotropin-releasing hormone (TRH). Bulimics and anorectics both tend to have a delayed thyrotropin (TSH) response to TRH and elevated basal GH levels. Bulimics, however, have a normal GH response to clonidine, a nonblunted TSH response to TRH, low basal prolactin (PRL) levels, and may have an exaggerated PRL response to TRH. Unpublished data suggest bulimics may have a gonadotropin profile distinct from either AN or depression, as well as a variety of other endocrinopathies. Although many of these abnormalities may reflect malnutrition despite normal weight, other factors that are as yet unidentified are likely to be contributing to the neuroendocrine abnormalities seen in bulimia.

Prevalence of binge-eating and bulimia among adolescent women in Japan

This study examined by questionnaire the prevalence of binge-eating and bulimia among 220 women at a school of nursing and 236 women at a junior college, all from 18 to 21 years old, in two different areas of Japan. Binge-eating more than once a week was found in 14 (6.5%) of the nursing school students and 21 (9.1%) of the college women. Self-induced vomiting and use of purgatives were found in 19 (8.7%) and 12 (5.5%) of the nursing school students, and 19 (8.1%) and 9 (3.8%) of the college women, respectively. The difference between these two groups was not significant. The prevalence of binge-eating more than once a week, together with self-induced vomiting or purgative use, was 3.6% in the nursing school students, 2.1% in the college women, and 2.9% in the total sample. These women appeared to meet both DSM-III criteria for bulimia and Russell's criteria for bulimia nervosa.

Prolactin in patients with major depressive disorder and in healthy subjects. I. Cross-sectional study of basal and post-TRH and postdexamethasone prolactin levels

Prolactin (PRL) levels were investigated in patients with major depressive illness and in healthy subjects. Basal and postdexamethasone levels were measured in 27 patients, and levels after thyrotropin-releasing hormone (TRH) stimulation (delta PRL) were measured in 22 patients. Basal and delta PRL were also determined in 64 age- and sex-matched healthy subjects. Both basal and postdexamethasone PRL levels were normal in depressed patients, with the postdexamethasone levels in particular showing no correlation to postdexamethasone cortisol concentrations. One milligram oral dexamethasone did not influence 4:00 PM PRL levels in 15 healthy subjects. delta PRL was significantly elevated in both male and female patients. These increases were not correlated with severity of illness and are difficult to interpret owing to the complexity of the PRL regulatory system. No significant correlations were found between basal or post-TRH PRL and cortisol, thyroid-stimulating hormone (TSH), thyroid hormones, gonadotropins, or estradiol in the patients. However, surprisingly significant positive correlations between basal PRL and basal cortisol, T4 and reverse T3 occurred in healthy subjects. It is as yet unclear how this finding can be explained and what relevance it has. Women tended to have higher basal PRL concentrations than men, but the difference was not significant in either group. delta PRL was significantly higher in women than in men in both patients and controls. No significant influence of age was found.

Gonadotropin response to LH-RH in anorexia nervosa and bulimia

Serum LH and FSH levels before and after stimulation with LH-RH were measured in 9 patients with bulimia, 7 with a restricting subtype and 6 with a bulimic subtype of anorexia nervosa. All patients with anorexia nervosa and 5 (56%) patients with bulimia showed amenorrhea for at least 5 months, while 4 (44%) of the bulimic patients showed oligomenorrhea. Mean basal levels of LH and FSH were low in patients with restricting and bulimic anorexia nervosa, but were normal in patients with bulimia. The response of LH and FSH to LH-RH was impaired in approximately half of the patients with the two subtypes of anorexia nervosa, whereas it was normal in all but one patient with bulimia. These results suggest that bulimic patients with amenorrhea or oligomenorrhea have hypothalamic dysfunctions, which do not appear to be due solely to low weight or to metabolic changes resulting from binge eating, vomiting or purgative use.

Pituitary response to TRH in bulimia

The response to thyrotropin-releasing hormone (TRH) of thyroid-stimulating hormone (TSH), growth hormone (GH), and prolactin (PRL) was examined in nine normal weight female bulimics without endogenous depression and eight female controls. Four bulimics had delayed peak TSH response, but none demonstrated a blunted TSH response, unlike that which has been reported in endogenous depression. Bulimics had elevated mean +/- SD serum GH levels (controls 1.6 +/- 1.4 ng/ml, bulimics 5.6 +/- 3.9) and an inappropriate GH release following TRH. Their mean +/- SD serum PRL (3.1 +/- 1.7 ng/ml) was lower than that of controls (4.7 +/- 1.3); however, the PRL response to TRH was significantly greater in bulimics than in controls. These data show that neuroendocrine abnormalities exist in normal weight bulimic women without endogenous depression and provide further evidence for a neuroendocrine component to this illness.

Growth hormone and somatomedin-C in bulimia

Somatomedin-C (SOM-C) concentrations are regulated by circulating growth hormone (GH) concentrations; however, other factors, such as nutrition, also influence SOM-C concentrations. We evaluated the GH-SOM-C axis in seven normal-weight female bulimics one day after hospital admission, and in seven age-, sex-, and weight-matched normal controls. Subjects were medication-free for at least one month. Fasting morning serum GH concentrations were higher in all bulimics (range 2.5-13.3 ng/ml) than in all controls (range less than 1.0-1.8 ng/ml). The mean (+/- SD) maximum GH response to TRH (500 micrograms) was greater in the bulimics (12.9 +/- 4.9 ng/ml) than in the controls (3.7 +/- 2.7 ng/ml) (p less than .001). Despite this GH elevation, the mean (+/- SD) SOM-C concentration was comparable in the bulimics (2.0 +/- 0.6 U/ml) and the controls (1.6 +/- 0.8 U/ml). This suggests that SOM-C generation is resistant to the elevated circulating GH in bulimia and that SOM-C is not inhibiting GH secretion in the pituitary-hypothalamic axis.