Predictive markers for mammoplasty and a comparison of side effect profiles in transwomen taking various hormonal regimens.

CONTEXT: Breast development in transwomen is an important issue, affecting general psychological functioning. Current hormonal therapies are imperfect, with 60% of patients requesting mammoplasty. INTERVENTIONS: Interventions included the following: 1) comparing the effects on transwomen's requests for mammoplasty of estrogen valerate, ethinylestradiol, and conjugated equine estrogen (CEE) hormone treatments; and 2) comparing the effects of GnRH analogs and androgen antagonists. OBJECTIVE: The objective of the study was to identify which hormone regimen is associated with the greatest subsequent request for augmentation mammoplasty. DESIGN: The study was a controlled, retrospective case audit. SETTING: The study was conducted at a single-center National Health Service tertiary care unit. PATIENTS: Patients were eligible for breast augmentation after 2 yr of estrogen treatment, were Tanner IV or higher breast development, and reported psychological distress due to small breasts. One hundred sixty-five subjects and 165 age-matched controls were identified. OUTCOME MEASURE: The outcome measure was a mammoplasty request. RESULTS: There were significantly more self-medicating individuals than controls in the mammoplasty group (11.5 vs. 6%, P < 0.05). The type of estrogen use did not affect the outcome. Compared with other antiandrogens, spironolactone use was significantly higher in those requesting mammoplasty (4.8 vs. 1.8%, P = 0.002). Thromboembolism occurred in 1.2% of individuals, more frequently in those treated with CEE than in those treated with either estrogen valerate or ethinylestradiol (4.4 vs. 0.6 vs. 0.7%, P = 0.026). Depression was noted in approximately 30% of individuals. CONCLUSIONS: Self-medication with estrogen is significantly more likely to result in a later request for mammoplasty than is treatment prescribed by licensed practitioners. Previous spironolactone use is more common in those requesting mammoplasty. CEE treatment is associated with a higher incidence of thromboembolism than treatment with other estrogen types.

A case of excess growth hormone levels.

Patients with anorexia nervosa are known to have elevated basal growth hormone levels, which fail to suppress normally during glucose tolerance testing. We describe a case of probable anorexia nervosa initially diagnosed as acromegaly despite a low insulin-like growth factor-1 level and treated with transsphenoidal surgery based on a pituitary microadenoma on magnetic resonance imaging and a lack of suppression of growth hormone levels during glucose tolerance testing. This case highlights, firstly, that pituitary magnetic resonance imaging will suggest a pituitary adenoma in up to 10% of normal individuals. Secondly, that a diagnosis of acromegaly should be made on clinical features as well as growth hormone measurements.

Effect of direct injection of melanin-concentrating hormone into the paraventricular nucleus: further evidence for a stimulatory role in the adrenal axis via SLC-1.

Melanin-concentrating hormone (MCH) is implicated in the control of a number of hormonal axes including the hypothalamic-pituitary adrenal (HPA) axis. Previous studies have shown that there is evidence for both a stimulatory and an inhibitory action on the HPA axis; therefore, we attempted to further characterize the effects of MCH on this axis. Intracerebroventricular injection of MCH increased circulating adrenocorticotropic hormone (ACTH) at 10 min post injection. Injection of MCH directly into the paraventricular nucleus (PVN) was found to increase both circulating ACTH and corticosterone 10 min after injection. Additionally, MCH was found to increase corticotropin-releasing factor (CRF) release from hypothalamic explants, and this effect was abolished by the specific SLC-1 antagonist SB-568849. Neuropeptide EI, a peptide from the same precursor as MCH was also found to increase CRF release from explants. These results suggest that MCH has a stimulatory role in the HPA axis via SLC-1, and that MCH exerts its effects predominantly through the PVN CRF neuronal populations

Agouti-related protein has an inhibitory paracrine role in the rat adrenal gland.

alpha-Melanocyte-stimulating-hormone (alpha-MSH) is an agonist at the melanocortin 3 receptor (MC3-R) and melanocortin 4 receptor (MC4-R). alpha-MSH stimulates corticosterone release from rat adrenal glomerulosa cells in vitro. Agouti-related protein (AgRP) an endogenous antagonist at the MC3-R and MC4-R, is expressed in the adrenal gland. We investigated the expression of the MC3-R and MC4-R and the role of AgRP in the adrenal gland. MC3-R and MC4-R expression was detected in rat adrenal gland using RT-PCR. The effect of AgRP on alpha-MSH-induced corticosterone release was investigated using dispersed rat adrenal glomerulosa cells. AgRP administered alone did not affect corticosterone release, but co-administration of AgRP and alpha-MSH attenuated alpha-MSH-induced corticosterone release. To investigate glucocorticoid feedback, adrenal AgRP expression was compared in rats treated with dexamethasone to controls. AgRP mRNA was increased in rats treated with dexamethasone treatment compared to controls. Our findings demonstrate that adrenal AgRP mRNA is regulated by glucocorticoids. AgRP acting via the MC3-R or MC4-R may have an inhibitory paracrine role, blocking alpha-MSH-induced corticosterone secretion.

Hypothalamic interactions between neuropeptide Y, agouti-related protein, cocaine- and amphetamine-regulated transcript and alpha-melanocyte-stimulating hormone in vitro in male rats.

A number of neuropeptides implicated in the hypothalamic regulation of appetite are synthesized in the arcuate nucleus (Arc). Neuropeptide Y (NPY) and agouti-related protein (Agrp) are orexigenic. The pro-opiomelanocortin (POMC) product alpha-melanocyte-stimulating hormone (alpha-MSH) is anorectic. Intracerebroventricular administration of cocaine- and amphetamine-regulated transcript (CART) decreases food intake. However, recent results show that CART is orexigenic when injected into discrete hypothalamic nuclei. There is almost complete coexpression of NPY and Agrp mRNA in Arc neurones, and the majority of CART-containing neurones in the Arc also contain POMC mRNA. We investigated possible interactions between these neuropeptides in vitro using a rat hypothalamic explant system. Administration of 1, 10 and 100 nm of NPY to hypothalamic explants significantly increased release of Agrp(83-132)-immunoreactivity (IR). NPY (10 and 100 nm) significantly increased the release of CART(55-102)-IR and alpha-MSH-IR from hypothalamic explants. Agrp(83-132) (10 nm) administered to hypothalamic explants significantly increased the release of NPY-IR. Agrp(83-132) (10 and 100 nm) significantly decreased the release of CART(55-102)-IR from hypothalamic explants. Administration of 1, 10 and 100 nm CART(55-102) to hypothalamic explants resulted in a significant increase in NPY-IR release. Administration of 10 nm CART(55-102) to hypothalamic explants significantly increased the release of Agrp(83-132)-IR. NDP-MSH (10 nm) administered to hypothalamic explants significantly increased the release of NPY-IR. NDP-MSH (10 and 100 nm) significantly increased the release of Agrp(83-132)-IR from hypothalamic explants. These data suggest that orexigenic neuropeptides in the arcuate nucleus stimulate the release of each other, perhaps reinforcing orexigenic behaviour via a positive-feedback loop. Our results are also in keeping with the possibility that the melanocortin-3 receptor in the arcuate nucleus may influence the release of arcuate neuropeptides.

Ghrelin enhances appetite and increases food intake in humans.

Ghrelin is a recently identified endogenous ligand for the growth hormone secretagogue receptor. It is synthesized predominantly in the stomach and found in the circulation of healthy humans. Ghrelin has been shown to promote increased food intake, weight gain and adiposity in rodents. The effect of ghrelin on appetite and food intake in man has not been determined. We investigated the effects of intravenous ghrelin (5.0 pmol/kg/min) or saline infusion on appetite and food intake in a randomised double-blind cross-over study in nine healthy volunteers. There was a clear-cut increase in energy consumed by every individual from a free-choice buffet (mean increase 28 +/- 3.9%, p<0.001) during ghrelin compared with saline infusion. Visual analogue scores for appetite were greater during ghrelin compared to saline infusion. Ghrelin had no effect on gastric emptying as assessed by the paracetamol absorption test. Ghrelin is the first circulating hormone demonstrated to stimulate food intake in man. Endogenous ghrelin is a potentially important new regulator of the complex systems controlling food intake and body weight.

Ghrelin causes hyperphagia and obesity in rats.

Ghrelin, a circulating growth hormone-releasing peptide derived from the stomach, stimulates food intake. The lowest systemically effective orexigenic dose of ghrelin was investigated and the resulting plasma ghrelin concentration was compared with that during fasting. The lowest dose of ghrelin that produced a significant stimulation of feeding after intraperitoneal injection was 1 nmol. The plasma ghrelin concentration after intraperitoneal injection of 1 nmol of ghrelin (2.83 +/- 0.13 pmol/ml at 60 min postinjection) was not significantly different from that occurring after a 24-h fast (2.79 +/- 0.32 pmol/ml). After microinjection into defined hypothalamic sites, ghrelin (30 pmol) stimulated food intake most markedly in the arcuate nucleus (Arc) (0-1 h food intake, 427 +/- 43% of control; P < 0.001 vs. control, P < 0.01 vs. all other nuclei), which is potentially accessible to the circulation. After chronic systemic or intracerebroventricular (ICV) administration of ghrelin for 7 days, cumulative food intake was increased (intraperitoneal ghrelin 13.6 +/- 3.4 g greater than saline-treated, P < 0.01; ICV ghrelin 19.6 +/- 5.5 g greater than saline-treated, P < 0.05). This was associated with excess weight gain (intraperitoneal ghrelin 21.7 +/- 1.4 g vs. saline 10.6 +/- 1.9 g, P < 0.001; ICV ghrelin 15.3 +/- 4.3 g vs. saline 2.2 +/- 3.8 g, P < 0.05) and adiposity. These data provide evidence that ghrelin is important in long-term control of food intake and body weight and that circulating ghrelin at fasting concentrations may stimulate food intake.

PRL-releasing peptide inhibits food intake in male rats via the dorsomedial hypothalamic nucleus and not the paraventricular hypothalamic nucleus.

PRL-releasing peptide inhibits food intake after intracerebroventricular injection. PRL-releasing peptide immunoreactivity is found in several hypothalamic nuclei involved in feeding, with highest levels in the paraventricular and dorsomedial hypothalamic nuclei. The aim of this study was to examine the effect of PRL-releasing peptide on food intake after administration into these nuclei. Paraventricular nucleus injection of PRL-releasing peptide did not alter food intake. Dorsomedial hypothalamic nucleus injection of PRL-releasing peptide decreased 1 h food intake [PRL-releasing peptide (1 nmol) 83.4 +/- 6.1% saline all; P < 0.05]; and continued until 8 h postinjection [PRL-releasing peptide (1 nmol) 89.2 +/- 4.1% saline; P < 0.05]. To investigate the mechanism of this inhibition of food intake, we examined PRL-releasing peptide's effect on neuropeptide release from hypothalamic explants. alpha MSH release was increased [PRL-releasing peptide (100 nmol), 5.4 +/- 1.6 pmol/explant; change vs. basal, P < 0.01], whereas agouti-related protein release was unchanged. The release of cocaine- and amphetamine-regulated transcript was inhibited [PRL-releasing peptide (100 nmol), -33.5 +/- 12.6 pmol/explant; change vs. basal, P < 0.01]. PRL-releasing peptide dose-dependently increased neurotensin release [PRL-releasing peptide (1 nmol), 3.7 +/- 2.6 pmol/explant; change vs. basal, P = NS; PRL-releasing peptide (10 nmol), 7.2 +/- 2.7 pmol/explant; change vs. basal, P < 0.01; PRL-releasing peptide (100 nmol), 36.8 +/- 5.4 pmol/explant; change vs. basal, P < 0.001]. Our data suggest that the dorsomedial hypothalamic nucleus is important in the inhibitory effect of PRL-releasing peptide on food intake and that PRL-releasing peptide alters the release of several hypothalamic neuropeptides important in the control of food intake.

Exendin-4 reduces fasting and postprandial glucose and decreases energy intake in healthy volunteers.

Exendin-4 is a long-acting potent agonist of the glucagon-like peptide 1 (GLP-1) receptor and may be useful in the treatment of type 2 diabetes and obesity. We examined the effects of an intravenous infusion of exendin-4 (0.05 pmol. kg(-1). min(-1)) compared with a control saline infusion in healthy volunteers. Exendin-4 reduced fasting plasma glucose levels and reduced the peak change of postprandial glucose from baseline (exendin-4, 1.5 +/- 0.3 vs. saline, 2.2 +/- 0.3 mmol/l, P < 0.05). Gastric emptying was delayed, as measured by the paracetamol absorption method. Volunteers consumed 19% fewer calories at a free-choice buffet lunch with exendin-4 (exendin-4, 867 +/- 79 vs. saline 1,075 +/- 93 kcal, P = 0.012), without reported side effects. Thus our results are in accord with the possibility that exendin-4 may be a potential treatment for type 2 diabetes, particularly for obese patients, because it acts to reduce plasma glucose at least partly by a delay in gastric emptying, as well as by reducing calorie intake.

Actions of cocaine- and amphetamine-regulated transcript (CART) peptide on regulation of appetite and hypothalamo-pituitary axes in vitro and in vivo in male rats.

Cocaine- and amphetamine-regulated transcript (CART) and CART peptide are abundant in hypothalamic nuclei controlling anterior pituitary function. Intracerebroventricular (ICV) injection of CART peptide results in neuronal activation in the paraventricular nucleus (PVN), rich in corticotrophin-releasing factor (CRH) and thyrotrophin-releasing factor (TRH) immunoreactive neurons. The aims of this study were three-fold. Firstly, to examine the effects of CART peptide on hypothalamic releasing factors in vitro, secondly, to examine the effect of ICV injection of CART peptide on plasma pituitary hormones and finally to examine the effect of PVN injection of CART peptide on food intake and circulating pituitary hormones. CART(55-102) (100 nM) peptide significantly stimulated the release of CRH, TRH and neuropeptide Y from hypothalamic explants but significantly reduced alpha melanocyte stimulating hormone release in vitro. Following ICV injection of 0.2 nmol CART(55-102), a dose which significantly reduces food intake, plasma prolactin (PRL), growth hormone (GH) and adrenocorticotrophin hormone (ACTH) and corticosterone increased significantly. Following PVN injection of CART(55-102), food intake was significantly reduced only at 0.2 and 0.6 nmol. However, PVN injection of 0.02 nmol CART(55-102) produced a significant increase in plasma ACTH. ICV injection of CART peptide significantly reduces food intake. Unlike many anorexigenic peptides, there is no increased sensitivity to PVN injection of CART(55-102). In contrast, both ICV and PVN injection of CART(55-102) significantly increased plasma ACTH and release of hypothalamic CRH is significantly increased by CART peptide in vitro. This suggests that CART peptide may play a role in the control of pituitary function and in particular the hypothalamo-pituitary adrenal axis.

Hypothalamic localization of the feeding effect of agouti-related peptide and alpha-melanocyte-stimulating hormone.

The melanocortin-4 receptor (MC4R) in the hypothalamus is thought to be important in physiological regulation of food intake. We investigated which hypothalamic areas known to express MC4R are involved in the regulation of feeding by using alpha-melanocyte-stimulating hormone (alpha-MSH), an endogenous MC4R agonist, and agouti-related peptide (Agrp), an endogenous MC4R antagonist. Cannulae were inserted into the rat hypothalamic paraventricular (PVN), arcuate (Arc), dorsomedial (DMN), and ventromedial (VMN) nuclei; the medial preoptic (MPO), anterior hypothalamic (AHA), and lateral hypothalamic (LHA) areas; and the extrahypothalamic central nucleus of the amygdala (CeA). Agrp (83-132) (0.1 nmol) and [Nle4, D-Phe7]alpha(-MSH (NDP-MSH) (0.1 nmol), a stable alpha-MSH analog, were administered to fed and fasted rats, respectively. The PVN, DMN, and MPO were the areas with the greatest response to Agrp and NDP-MSH. At 8 h postinjection, Agrp increased feeding in the PVN by 218 +/- 23% (P < 0.005), in the DMN by 268 +/- 42% (P < 0.005), and in the MPO by 236 +/- 31% (P < 0.01) compared with a saline control group for each nucleus. NDP-MSH decreased food intake in the PVN by 52 +/- 6% (P < 0.005), in the DMN by 44 +/- 6% (P < 0.0001), and in the MPO by 55 +/- 6% (P < 0.0001) at 1 h postinjection. Injection into the AHA and CeA resulted in smaller alterations in food intake. No changes in feeding were seen after the administration of Agrp into the Arc, LHA, or VMN, but NDP-MSH suppressed food intake in the Arc and LHA. This study indicates that the hypothalamic nuclei expressing MC4R vary in their sensitivity to Agrp and alpha-MSH with regard to their effect on feeding.

Prolactin releasing peptide (PrRP) stimulates luteinizing hormone (LH) and follicle stimulating hormone (FSH) via a hypothalamic mechanism in male rats.

Prolactin releasing peptide (PrRP) was originally isolated as an endogenous hypothalamic ligand for the hGR3 orphan receptor. It has been shown to release prolactin from dispersed pituitaries harvested from lactating female rats and only at very high doses in cycling females. PrRP is reported to have no effect on prolactin production from dispersed pituitary cells harvested from males. The CNS distribution of this peptide suggested a role for PrRP in the control of the hypothalamo-pituitary axis. The aim of this study was to examine the actions of PrRP (1-31) on circulating pituitary hormones following intracerebroventricular (ICV) injection in male rats and to investigate the mechanism of PrRP's effect by measurement of hypothalamic releasing factors in vitro. In our experiments, PrRP (1-31) did not release LH, FSH, TSH, growth hormone or prolactin directly from dispersed male pituitary cells in vitro. We have shown for the first time that following ICV injection of PrRP (1-31) 5 nmol there was a highly significant simulation of plasma LH that began at 10 minutes and was maintained over the course of the experiment (at 60 minutes PrRP 5 nmol 2.2 +/- 0.2 vs. saline 0.5 +/- 0.1 ng/ml, p<0.001). Plasma FSH increased at 20 minutes following ICV injection (PrRP 5nmol 10.8 +/- 2.0 ng/ml vs. saline 5.1 +/- 0.5, p<0.01). Total plasma testosterone increased at 60 minutes post injection (PrRP 5nmol 9.2 +/- 1.6 vs. saline 3.5 +/- 0.6 nmol/l, p<0.01). There was no significant alteration in plasma prolactin levels. PrRP significantly increased the release of LHRH from hypothalamic explants in vitro (PrRP 100nmol/l 180.5 +/- 34.5% of the basal secretion, p<0.05). PrRP (100nmol/l) also increased the following hypothalamic peptides involved in the control of pituitary hormone release, vasoactive intestinal peptide (VIP) 188.1 +/- 24.6% and galanin 153.8 +/- 13.0% (both p<0.001 vs. basal secretion) but had no effect on orexin A secretion. These results suggest a role for PrRP in the control of gonadotrophin secretion acting via a hypothalamic mechanism involving the release of LHRH.

The central melanocortin system affects the hypothalamo-pituitary thyroid axis and may mediate the effect of leptin.

Prolonged fasting is associated with a downregulation of the hypothalamo-pituitary thyroid (H-P-T) axis, which is reversed by administration of leptin. The hypothalamic melanocortin system regulates energy balance and mediates a number of central effects of leptin. In this study, we show that hypothalamic melanocortins can stimulate the thyroid axis and that their antagonist, agouti-related peptide (Agrp), can inhibit it. Intracerebroventricular (ICV) administration of Agrp (83-132) decreased plasma thyroid stimulating hormone (TSH) in fed male rats. Intraparaventricular nuclear administration of Agrp (83-132) produced a long-lasting suppression of plasma TSH, and plasma T4. ICV administration of a stable alpha-MSH analogue increased plasma TSH in 24-hour-fasted rats. In vitro, alpha-MSH increased thyrotropin releasing hormone (TRH) release from hypothalamic explants. Agrp (83-132) alone caused no change in TRH release but antagonized the effect of alpha-MSH on TRH release. Leptin increased TRH release from hypothalami harvested from 48-hour-fasted rats. Agrp (83-132) blocked this effect. These data suggest a role for the hypothalamic melanocortin system in the fasting-induced suppression of the H-P-T axis.