Effects of long-term oral testosterone undecanoate therapy on urinary symptoms: data from a 1-year, placebo-controlled, dose-ranging trial in aging men with symptomatic hypogonadism.

BACKGROUND: There has been a longstanding question as to whether testosterone therapy could precipitate or worsen urinary symptoms in aging men. We investigated the effects of 1-year oral testosterone undecanoate (TU) therapy on urinary symptoms in aging, hypogonadal men. METHODS: A total of 322 men ≥50 years with symptomatic testosterone deficiency participated in a 1-year, randomized, multicenter, double-blind trial. Patients received placebo or oral TU 80 mg/day, 160 mg/day, or 240 mg/day. RESULTS AND LIMITATIONS: Compared with placebo, treatment with oral TU at doses of 80 mg/day and 160 mg/day resulted in no significant change in IPSS urinary symptoms or quality of life (QoL) scores. Treatment with oral TU 240 mg/day led to a statistically significant, but clinically insignificant, improvement in IPSS total score and a significant improvement in IPSS QoL score. None of the TU doses tested had a significant effect on PSA or PV. CONCLUSIONS: Long-term oral TU therapy had no deleterious effects on IPSS total score and did not change PV and PSA in aging, hypogonadal men. Oral TU therapy at a dose of 240 mg/day may even improve IPSS QoL score.

Prostate-specific antigen (PSA) concentrations in hypogonadal men during 6 years of transdermal testosterone treatment.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Hypogonadism affects an estimated 2-4 million men in the USA, but only 5% receive treatment. Testosterone replacement therapy reduces the effects of testosterone deficiency on sexual function, mood and energy in hypogonadal patients. Long-term hypogonadism management requires testosterone treatment to restore serum concentrations of testosterone and its active metabolites, within physiological ranges; a testosterone preparation that achieves physiological plasma concentrations without supra-physiological escape is a preferred option. A previous 1-year study European clinical study showed the efficacy and safety of a transdermal testosterone patch (Testopatch(®) ). The present study shows the long-term (6-year) safety and efficacy of Testopatch in patients with primary or secondary hypogonadism. We show that, over the long-term, Testopatch was associated with no relevant changes in PSA concentration and PSA velocity, or any significant prostate risks (there were no cases of prostate cancer). OBJECTIVE: To assess the change in prostate-specific antigen (PSA) concentrations in patients with primary or secondary hypogonadism, receiving transdermal testosterone. PATIENTS AND METHODS: This was an interventional, 6-year study, conducted in Urology and Endocrinology centres in Belgium, France, Germany, the Netherlands and Spain. Participants were primary (48%) or secondary (52%) hypogonadal patients who received two 60 cm(2) testosterone patches (Testopatch(®) ), delivering 4.8 mg of testosterone per day, applied every 2 days. During treatment, total testosterone (TT), dihydrotestosterone, oestradiol and, PSA concentrations were measured in a centralised laboratory every 3 months during the first year, and every 6 months thereafter. RESULTS: In all, 200 patients [mean (sd) age 41.0 (12.5) years, body weight 82.5 (13.7) kg, height 177.2 (9.3) cm, body mass index 26.2 (3.4) kg/m(2) ] were treated with transdermal testosterone patches. In all, 161 patients completed the 1-year study and 115 entered into a 5-year study extension; 51 patients completed the sixth year of the study. The mean baseline concentrations of TT and PSA were 1.4 ng/mL and 0.47 ng/mL, respectively; TT serum concentrations >3 ng/mL were achieved in 85% of patients and fluctuated between 4.4 and 6.0 ng/mL. At each successive 6-month time point, mean the PSA values were 0.60, 0.67, 0.76, 0.70, 0.61, 0.68, 0.64, 0.71, 0.75, 0.74, 1.01, 0.78, 0.80 ng/mL, respectively. The mean PSA velocity was negligible (0.00-0.03 ng/mL/year) from 30 months to the end of the trial, except for a value of 0.08 at 60 months. Seven patients had a PSA concentration of >4 ng/mL due to a sharp PSA increase. Six of these patients had prostatitis and PSA concentrations returned to previous levels with appropriate treatment. No prostate cancer was reported during the trial. CONCLUSION: These data support a strong safety profile for Testopatch, even at the highest registered dosage.

Effects of oral testosterone undecanoate therapy on bone mineral density and body composition in 322 aging men with symptomatic testosterone deficiency: a 1-year, randomized, placebo-controlled, dose-ranging study.

OBJECTIVE: We investigated the effects of oral testosterone undecanoate (TU) on bone mineral density (BMD), lean body mass (LBM) and body fat mass (BFM) in aging men with symptomatic testosterone deficiency (TD). METHODS: Three hundred twenty-two men ≥50 years with TD symptoms and calculated free testosterone <0.26 nmol/L participated in a multicenter, double-blind, placebo-controlled trial. Patients were randomized to placebo, oral TU 80 mg/d, oral TU 160 mg/d, or oral TU 240 mg/d, administered as divided doses with normal meals. BMD of the hip and lumbar spine were evaluated by dual energy X-ray absorptiometry (DEXA), and body composition (LBM and BFM) by whole body DEXA. RESULTS: Oral TU significantly increased BMD at Month 12 at the lumbar spine (240 mg/d), total hip (240 mg/d), and trochanter and intertrochanter (160 and 240 mg/d) compared with placebo. Oral TU significantly increased LBM at Months 6 and 12 for all oral TU groups compared with placebo. BFM significantly decreased at Month 6 (all oral TU groups) and Month 12 (160 mg/d) compared with placebo. The effects on BMD and body composition showed a clear dose response. CONCLUSIONS: Treatment with oral TU led to improvement in BMD, LBM and BFM in aging men with symptomatic TD.

Efficacy and safety of a new testosterone-in-adhesive matrix patch applied every 2 days for 1 year to hypogonadal men.

OBJECTIVES: To study long-term efficacy and safety of a testosterone-in-adhesive matrix patch, delivering 4.8 mg of testosterone daily. METHODS: Randomized, open label, multicenter 1-year study. 224 hypogonadal patients were included. 188 received 2 patches of 60 cm2 every 48 h and 36 patients had IM testosterone enanthate injection every 3 weeks. T, bioavailable T (BT), DHT, E2, LH, FSH and SHBG and clinical symptom scores (AMS and MSF-4) were assessed at 3, 6 and 12 months. RESULTS: In the patch group, T serum levels were above 3 ng/mL in 85% of patients and remained stable over time. BT, DHT and E2 levels were restored within physiological range. BT/T ratio varied from 20 to 70%. In the IM group, the percentages of "normalized" patients appeared to be lower, although the two groups cannot be adequately compared due to the kinetic profile of T following IM administration, resulting in greater variations of serum T levels, blood samplings occurring randomly at time of peak, trough, or in between. A significant correlation was found between T, BT and the MSF-4 changes. BT levels were significantly related to total AMS score. PSA values showed a mean (S.D.) increase of 0.13 (0.38), 0.23 (0.79) and 0.30 (1.47)ng/mL at weeks 14, 27 and 53, respectively. The patch was well tolerated with no negative impact either on lipid profile, or red blood cells. Administration site reactions occurred in 35 patients (18.8%). Adhesiveness was good (>or=75%) in >90% patients over the 1 year application period. CONCLUSION: Two 60 cm2 patches, allowed constant physiological levels of sexual hormones over time. This new patch was well tolerated, easy to use, well accepted by the patients and displayed a very good adhesiveness. Clinical efficacy was more related to BT than to T.

Vasopressin-neurophysin and DST in major depression: relationship with suicidal behavior.

The purpose of the present study was to assess if AVP-neurophysin is associated with hypercortisolemia and suicidal behaviour in depressed patients. The study included 28 patients subgrouped into suicide attempters (n=13) and nonattempters (n=15). We assessed basal AVP-neurophysins concentrations and post-dexamethasone (DST) cortisol levels. Concentrations of AVP-neurophysins did not differ between DST suppressors and nonsuppressors: 0.29+/-0.13 ng/ml vs 0.36+/-0.21 ng/ml, (F=1.1, df=1, 27, p=0.30). Suicide attempters did not differ from nonattempters for AVP-neurophysins levels. Our results fail to support a role of AVP in the early cortisol escape.

Oxytocin synthesis and oxytocin receptor expression by cell lines of human small cell carcinoma of the lung stimulate tumor growth through autocrine/paracrine signaling.

The objective of the present work was to investigate the existence of an oxytocin (OT)-mediated autocrine/paracrine signaling upon small cell carcinoma of the lung (SCCL) cell growth. In that view, OT receptor (OTR) expression, concomitant with OT synthesis and secretion, was evidenced on three different SCCL cell lines (DMS79, H146, and H345) and related to the vasopressin (VP) system. Specific OT, VP, OTR, V1a VP receptor (V1aR), and V1b/V3 VP receptor (V1bR/V3R) transcripts were identified by reverse transcription-PCR in all cell lines studied. Binding of 125I-(d(CH2)(5)(1), Tyr(Me)(2),Thr(4),Orn(8),Tyr(9)-NH2)-vasotocin (OVTA) was observed on all SCCL cell lines, with a K(d) (dissociation constant) ranging from 0.025-0.089 nM, depending on the cell line and the analytical method. Selectivity of 125I-OVTA binding was confirmed by displacement curves obtained with various OTR and VP receptor agonists and antagonists (OT, OVTA, L-371,257, VP, F180). Immunocytochemistry identified cellular OT and VP, and peptide secretion was measured in supernatants of SCCL cultures. [3H]Thymidine incorporations, applied on H345 cells, demonstrated a dose-dependent mitogenic effect of exogenous OT (1 and 100 nM) that was abolished by the OTR antagonist OVTA. A decrease of proliferation was also observed with OVTA alone, showing a functional mitogenic effect of tumor-derived OT. Taken together, these observations demonstrate the existence of a functional OT-mediated autocrine/paracrine signaling actively implicated in growth and development of SCCL tumors. Furthermore, these findings point to the potential of OT antagonists for development as therapeutic agents for the treatment of SCCL.

No major month to month variation in free testosterone levels in aging males. Minor impact on the biological diagnosis of 'andropause'.

BACKGROUND: The measurement of bioavailable testosterone (BT) or free testosterone (FT) levels is currently considered the gold standard for the diagnosis of androgen deficiency in elderly men. While the impact of age on circulating testosterone levels (total, bioavailable and free) has been strongly documented, the existence of seasonal variations in testosterone levels remains debated. OBJECTIVE: We investigated whether seasonal variations in serum calculated free testosterone (cFT) levels may translate into variations in the prevalence of low testosterone levels. Diagnosis was on the basis of biochemical determinations and was cross-checked with the prevalence of clinical signs and symptoms of 'andropause', as assessed by the Androgen Deficiency in Aging Males (ADAM) questionnaire. METHODS: The study recruited 5028 men aged 50 years and over from September 2000 to January 2003. Their serum FT levels were assessed and they completed the French ADAM test. Men were considered eugonadal when cFT was > or =70 ng/l. The ADAM test was scored as described originally. The prevalence of 'andropause', diagnosed by the two methods, was compared throughout the year, on a month by month basis. RESULTS: The percentage of subjects with cFT levels below 70 ng/l increased significantly with age (P<0.001). Serum cFT levels (mean [SD]) varied significantly with the month of sampling (P<0.0001), the highest (88.1 [30.2] ng/l) and lowest (76.9 [28.0] ng/l) mean values occurring in April and in October, respectively. Conversely, the prevalence of testosterone deficiency (cFT<70 ng/l) reached a peak in October (45.7%) and a nadir in April (29.7%). Although the prevalence of 'andropause', based on the ADAM questionnaire, increased significantly with age (P<0.0001), no influence of the month of the year was noticed. CONCLUSIONS: Our results confirm a progressive age-related decline in FT levels. The monthly variations in serum FT values, observed throughout the year, do not show a major seasonal rhythm in elderly community-dwelling males, since the magnitude of the variations (<15%) remains marginal. This slight variation may, however, have an impact on the number of elderly men diagnosed with Partial Androgen Deficiency in Aging Males (PADAM).

Oxytocin receptor pattern of expression in primary lung cancer and in normal human lung.

In order to assess if oxytocin- and vasopressin-induced mitogenic effects detected on small-cell lung carcinoma (SCLC) cell lines could be transposed on primary SCLC, the aim of the present work was to identify mediators of these mitogenic actions on primary tumours samples. This was addressed on normal human lung tissue, on SCLC and on non-SCLC (NSCLC). Herein, we observe, in normal human lung, that OTR is colocalized with vascular endothelial cells of the lung and is not expressed by lung cells of epithelial nature. We detected mRNA amplification of V1aR, V2R and of a V2R variant. We observed that 86% of SCLC biopsies analyzed expressed at least the OTR and that 71% expressed the OTR, the V1aR and the V2R altogether. Comparatively, 50% of NSCLC biopsies tested expressed at least the OTR and 32% expressed the OTR, the V1aR and the V2R altogether. The occurrence of the V1bR/V3R is of 28 and 18% for SCLC and NSCLC, respectively. Nevertheless, for the SCLC biopsies analyzed in this study, V1bR/V3R expression correlates, in all cases, with the expression of all the other neurohypophysial peptide receptors. Our results suggest that neurohypophysial peptide antagonists may offer promise as a potential new therapeutic modality for the treatment of lung cancer expressing at least one of the neurhypophysial peptide receptor subtypes.

Interest of the androgen deficiency in aging males (ADAM) questionnaire for the identification of hypogonadism in elderly community-dwelling male volunteers.

OBJECTIVE: To date, serum free testosterone measurement is considered to be the gold standard for the diagnosis of hypogonadism in elderly males but it is not available to all subjects suspected of a decrease in testicular function. Therefore, we evaluated whether the Androgen Deficiency in Aging Males (ADAM) questionnaire, in its original or in a modified 'quantitative' version (qADAM), could be used as a surrogate to biochemical determinations for the identification of hypogonadism in elderly males. METHODS: 5028 men, aged 50-70 years, spontaneously consulting for the assessment of their gonadal function were studied. ADAM and qADAM, allocating a value of 1 point for any positive answer to each of the 10 questions of the ADAM test, were assessed for their ability to discriminate between males with free testosterone levels below or above 70 ng/l. RESULTS: The sensitivity and specificity of the ADAM score were 81% and 21.6% respectively. The use of ADAM resulted in an appropriate classification of our population in normal or hypogonadal subjects in 44.5% of the cases. The area under the receiver operating characteristics (ROC) curve for the qADAM (0.529) revealed a highly marginal interest of this quantitative approach compared with the original scoring system. CONCLUSIONS: The ADAM test has a high sensitivity to identify aging males with low free testosterone levels. However, due to its lack of specificity, this test cannot be used as a surrogate to serum free testosterone testing for the identification of androgen deficiency in elderly, community-dwelling males.

Andropause and psychopathology: minor symptoms rather than pathological ones.

This study examined the psychological symptomatology of men diagnosed with andropause and the association between calculated free testosterone (T) and depressed mood, anxiety and quality of life. Subjects were 153 men, aged 50-70 years, who participated in a screening of andropause. Total testosterone, FSH, LH and SHBG levels were measured. Depressed mood was assessed with the Carroll Rating Scale, anxiety with the "anxiety-insomnia" dimension of the General Health Questionnaire, and quality of life with the World Health Organisation Quality of Life questionnaire. The results showed that levels of free T decreased with age, whereas FSH and LH increased. Carroll Rating Scale scores were higher among hypogonadal subjects, but the mean score was low and not pathological. A negative correlation was observed between severity of depression as assessed by the Carroll Rating Scale and free T levels. However, subjects with a significant score on this scale did not exhibit different free T levels compared to subjects with a non-significant depressive score. Anxiety and quality of life did not differ between hypogonadal and eugonadal subjects. The present study therefore suggests that andropause is not characterised by specific psychological symptoms, but may be associated with "depressive symptoms" that are not considered as pathological.

Hormonal and temperature responses to the 5-HT1A receptor agonist flesinoxan in normal volunteers.

RATIONALE: Flesinoxan is a highly potent and selective 5-HT(1A) agonist and appears to be a potentially interesting neuroendocrine serotonergic probe. OBJECTIVES: We assessed hormonal (ACTH, cortisol, prolactin and growth hormone) and temperature responses to flesinoxan in normal volunteers. METHODS: In a double-blind placebo-controlled study, single doses of 0.5 mg and 1 mg were injected over 10 min into 12 healthy male volunteers at 1-week intervals. Temperature and hormonal responses were measured at times -30, 0, 15, 30, 60, 90, and 120 min. RESULTS: Flesinoxan induced a significant and dose-dependent increase in adrenocorticotropic hormone (ACTH), cortisol, prolactin (PRL), growth hormone (GH) and a decrease in body temperature. Tolerance to flesinoxan was excellent. CONCLUSIONS: These results showed the role of 5-HT(1A) mechanisms in the PRL, ACTH, cortisol, GH, and temperature responses to flesinoxan. In the present study, flesinoxan appears a very promising serotonergic neuroendocrine probe.

Reciprocal interactions between the GH axis and sleep.

For more than 30 years, growth hormone (GH) has been observed to be preferentially secreted during deep, slow-wave sleep (SWS). However, the mechanisms that underlie this robust relationship that links anabolic processes in the body with behavioral rest and decreased cerebral metabolism remain to be elucidated. Current evidence indicates that GH secretion during the beginning of sleep appears to be primarily regulated by GH-releasing hormone (GHRH) stimulation occurring during a period of relative somatostatin withdrawal, which also is associated with elevated levels of circulating ghrelin. Apparently, two populations of GHRH neurons need to be simultaneously active to stimulate, in a coordinated fashion, SWS and pituitary GH release. Pharmacological interventions that are capable of increasing the duration and/or the intensity of SWS such as oral administration of gamma-hydroxybutyrate (GHB), also increase the rate of GH release. Because the normal negative feedback exerted by GH on central GHRH is inoperative in patients with GH deficiency, it is possible that the decreased energy levels and fatigue often reported by GH-deficient adults partly reflect an alteration in sleep-wake regulation. Preliminary data from a sleep study of adults with GH deficiency using wrist actigraphy for 6 nights at home and polysomnography in the laboratory indeed show decreased total sleep time and increased sleep fragmentation in GH-deficient patients as compared with normal controls.

Minimal effects of JL 13, a pyridobenzoxazepine derivative with an antipsychotic potential, on circulating prolactin levels in male rats.

Antipsychotic therapy is frequently associated with several side effects such as hyperprolactinemia. The influence of a putative antipsychotic JL 13 on prolactin release was assessed after intraperitoneal injection in gentled male rats in comparison with clozapine and haloperidol. A total of 30 or 150 min after administration, whole blood was collected for preparing serum samples. Prolactin was quantified by radioimmunoassay method. At 30 min, JL 13 like clozapine, increased prolactin concentration only at the higher dose (30 mg/kg) while haloperidol at both tested doses induced a dramatic increase of prolactin concentration. At 150 min after injection, only haloperidol (0.3 mg/kg) significantly increased serum prolactin level. This minimal effect on prolactinemia reinforces the similarity of clozapine and JL 13 regarding the atypical antipsychotic profile.

Hormonal and temperature responses to flesinoxan in normal volunteers: an antagonist study.

RATIONALE: Flesinoxan is a highly potent and selective 5-HT1A agonist. In a recent study, in normal volunteers, flesinoxan induced a significant and dose-dependent increase in adrenocorticotropic hormone (ACTH), cortisol, prolactin (PRL), growth hormone (GH) and a decrease in body temperature. OBJECTIVES: In order to better define the role of 5-HT receptor subtypes in response to flesinoxan, we assessed the influence of 5-HT1A and 5-HT2 antagonists on hormonal and temperature responses to flesinoxan. METHODS: Hormonal and temperature responses were studied in 6 volunteers with or without pretreatment with pindolol (30 mg p.o.), a 5-HT1A antagonist, or ritanserin (10 mg p.o.), a selective 5-HT2 antagonist, using a double-blind crossover design. RESULTS: Pindolol significantly antagonized ACTH, PRL, GH and temperature responses to flesinoxan and ritanserin exhibited similar activity on PRL and ACTH responses. CONCLUSIONS: These results show the role of 5-HT1A mechanisms in the PRL, ACTH, GH, and temperature responses to flesinoxan, and the role of 5-HT2 mechanisms in PRL and ACTH responses. Therefore, they confirm the interest of flesinoxan as a 5-HT neuroendocrine probe.

Familial colloid cyst of the third ventricle: neuroendocrinological follow-up and review of the literature.

Colloid cysts of the third ventricle are rare, benign cysts of endodermal origin. Between 1989 and 1999, eight patients with this lesion (five females, three males), with a mean age of 40.5 years (range 20-54), were identified out of 1354 operated for tumours of the central nervous system. Among the eight, two were familial. They were half sisters 38 and 28 years-old, who were diagnosed to have colloid cysts of the third ventricle on CT scanning. Transcortical excision yielded 10 and 15 mm sized colloid cysts, respectively. Moreover, both sisters developed a multinodular goiter associated with these congenital tumours. The second sibling developed hyperprolactinemia associated with macroprolactinemia. Pregnancy was only possible after bromocriptine treatment. These cases provide further evidences that colloid cysts probably have an autosomic recessive pattern of inheritance with variable penetrance.

[Investigation, treatment and surveillance of late-onset hypogonadism in males: the official guidelines of the International Society for the Study of the Aging Male (ISSAM) with comments]. / Diagnostic, traitement et surveillance de l'hypogonadisme de survenue tardive chez l'homme : recommandations officielles de l'International Society for the Study of the Aging Male (ISSAM) et commentaires.

There is growing interest in the hormonal changes of the ageing male, particularly in view of the expected growth of the population of males over the age of 50. Current research topics essentially concern androgen decline in the aging male (ADAM), or partial androgen deficiency of the aging male (PADAM), commonly called "andropause" in France. Although progress has been made in our knowledge concerning androgen deficiency of the aging male, it is still incomplete, sometimes confused, and some aspects of androgen replacement therapy remain controversial. The International Society for the Study of the Aging Male (ISSAM) therefore considered it appropriate to propose a series of practical and official guidelines concerning the investigation, treatment and surveillance of late-onset hypogonadism in males. The French translation of these recent international guidelines is presented and discussed in this article.

Impact of GH replacement therapy on sleep in adult patients with GH deficiency of pituitary origin.

OBJECTIVES: We previously reported that adult patients with GH deficiency (GHD) due to a confirmed or likely pituitary defect, compared with healthy controls individually matched for age, gender, and BMI, have more slow-wave sleep (SWS) and higher delta activity (a marker of SWS intensity). Here, we examined the impact of recombinant human GH (rhGH) therapy, compared with placebo, on objective sleep quality in a subset of patients from the same cohort. DESIGN: Single-blind, randomized, crossover design study. METHODS: Fourteen patients with untreated GHD of confirmed or likely pituitary origin, aged 22-74 years, participated in the study. Patients with associated hormonal deficiencies were on appropriate replacement therapy. Polygraphic sleep recordings, with bedtimes individually tailored to habitual sleep times, were performed after 4 months on rhGH or placebo. RESULTS: Valid data were obtained in 13 patients. At the end of the rhGH treatment period, patients had a shorter sleep period time than at the end of the placebo period (479±11 vs 431±19 min respectively; P=0.005), primarily due to an earlier wake-up time, and a decrease in the intensity of SWS (delta activity) (559±125 vs 794±219 µV(2) respectively; P=0.048). CONCLUSIONS: Four months of rhGH replacement therapy partly reversed sleep disturbances previously observed in untreated patients. The decrease in delta activity associated with rhGH treatment adds further evidence to the hypothesis that the excess of high-intensity SWS observed in untreated pituitary GHD patients is likely to result from overactivity of the hypothalamic GHRH system due to the lack of negative feedback inhibition by GH.

Mechanisms of the anti-obesity effects of oxytocin in diet-induced obese rats.

Apart from its role during labor and lactation, oxytocin is involved in several other functions. Interestingly, oxytocin- and oxytocin receptor-deficient mice develop late-onset obesity with normal food intake, suggesting that the hormone might exert a series of beneficial metabolic effects. This was recently confirmed by data showing that central oxytocin infusion causes weight loss in diet-induced obese mice. The aim of the present study was to unravel the mechanisms underlying such beneficial effects of oxytocin. Chronic central oxytocin infusion was carried out in high fat diet-induced obese rats. Its impact on body weight, lipid metabolism and insulin sensitivity was determined. We observed a dose-dependent decrease in body weight gain, increased adipose tissue lipolysis and fatty acid ß-oxidation, as well as reduced glucose intolerance and insulin resistance. The additional observation that plasma oxytocin levels increased upon central infusion suggested that the hormone might affect adipose tissue metabolism by direct action. This was demonstrated using in vitro, ex vivo, as well as in vivo experiments. With regard to its mechanism of action in adipose tissue, oxytocin increased the expression of stearoyl-coenzyme A desaturase 1, as well as the tissue content of the phospholipid precursor, N-oleoyl-phosphatidylethanolamine, the biosynthetic precursor of the oleic acid-derived PPAR-alpha activator, oleoylethanolamide. Because PPAR-alpha regulates fatty acid ß-oxidation, we hypothesized that this transcription factor might mediate the oxytocin effects. This was substantiated by the observation that, in contrast to its effects in wild-type mice, oxytocin infusion failed to induce weight loss and fat oxidation in PPAR-alpha-deficient animals. Altogether, these results suggest that oxytocin administration could represent a promising therapeutic approach for the treatment of human obesity and type 2 diabetes.