Long-term outcomes of vulvar or vaginal cancer patients undergoing laparoendoscopic single-site inguinal lymphadenectomy.

INTRODUCTION: Laparoendoscopic single-site inguinal lymphadenectomy (LESS-IL), a minimally invasive technique, has been reported in patients with vulvar or vaginal cancer regarding its safety and feasibility. However, the long-term outcomes, especially oncologic outcomes, are still lacking. We aimed to evaluate the long-term outcomes of LESS-IL to confirm its safety further. PATIENTS AND METHODS: Data were prospectively collected from patients with vulvar or vaginal cancer who underwent LESS-IL at our institution between July 2018 and June 2021. The patients were followed up for at least 12 months. All procedures were performed according to treatment standards. Short- and long-term complications and oncologic outcomes were analysed. RESULTS: A total of 16 patients undergoing 28 LESS-IL procedures were identified, amongst whom 4 underwent unilateral LESS-IL. The median numbers of excised groin lymph nodes were 9.0 (6.5-11.8) and 10.5 (8.3-12.0) in each left and right groin, respectively. Short-term complications occurred in 4 (25%) patients, including 18.7% lymphocele and 6.3% wound infection. Long-term complications regarding lower-limb lymphoedema appeared in 6 (37.5%) patients. Most short- and long-term complications were Clavien-Dindo 1 or 2, accounting for 90% of all post-operative issues. After a median follow-up of 27 (21.3-35.8) months, only 1 (6.3%) patient had isolated inguinal recurrence at 13 months postoperatively. No local or distant recurrence occurred. CONCLUSION: Our results suggest that LESS-IL is associated with little incidence of complications and promising oncologic outcomes, further demonstrating the safety and feasibility of the LESS-IL technique in patients requiring IL.

The design and synthesis of potent, selective benzodiazepine sulfonamide bombesin receptor subtype 3 (BRS-3) agonists with an increased barrier of atropisomerization.

Bombesin receptor subtype 3 (BRS-3) is an orphan G-protein coupled receptor expressed primarily in the hypothalamus which plays a role in the onset of both diabetes and obesity. We report herein our progress made towards identifying a potent, selective bombesin receptor subtype-3 (BRS-3) agonist related to the previously described MK-7725(1) Chobanian et al. (2012) that would prevent atropisomerization through the increase of steric bulk at the C-2 position. This would thereby make clinical development of this class of compounds more cost effective by inhibiting racemization which can occur over long periods of time at room/elevated temperature.

Percutaneous Endoscopic Posterior Lumbar Interbody Fusion with Unilateral Laminotomy for Bilateral Decompression Vs. Open Posterior Lumbar Interbody Fusion for the Treatment of Lumbar Spondylolisthesis.

Background: Endoscopic lumbar interbody fusion is a new technology that is mostly used for single-segment and unilateral lumbar spine surgery. The purpose of this study is to introduce percutaneous endoscopic posterior lumbar interbody fusion (PE-PLIF) with unilateral laminotomy for bilateral decompression (ULBD) for lumbar spondylolisthesis and evaluate the efficacy by comparing it with open posterior lumbar interbody fusion (PLIF). Methods: Twenty-eight patients were enrolled in PE-PLIF with the ULBD group and the open PLIF group. The perioperative data of the two groups were compared to evaluate the safety of PE-PLIF with ULBD. The visual analog scale (VAS) back pain, VAS leg pain, and Oswestry Disability Index (ODI) scores of the two groups preoperatively and postoperatively were compared to evaluate clinical efficacy. Preoperative and postoperative imaging data were collected to evaluate the effectiveness of the operation. Results: No differences in baseline data were found between the two groups (p > 0.05). The operation time in PE-PLIF with the ULBD group (221.2 ± 32.9 min) was significantly longer than that in the PLIF group (138.4 ± 25.7 min) (p < 0.05), and the estimated blood loss and postoperative hospitalization were lower than those of the PLIF group (p < 0.05). The postoperative VAS and ODI scores were significantly improved in both groups (p < 0.05), but the postoperative VAS back pain score in the PE-PLIF group was significantly lower than that in the PLIF group (p < 0.05). The excellent and good rates in both groups were 96.4% according to MacNab's criteria. The disc height and cross-sectional area of the spinal canal were significantly improved in the two groups after surgery (p < 0.05), with no difference between the groups (p > 0.05). The fusion rates in PE-PLIF with the ULBD group and the PLIF group were 89.3% and 92.9% (p > 0.05), respectively, the cage subsidence rates were 14.3% and 17.9% (p > 0.05), respectively, and the lumbar spondylolisthesis reduction rates were 92.72 ± 6.39% and 93.54 ± 5.21%, respectively (p > 0.05). Conclusion: The results from this study indicate that ULBD can be successfully performed during PE-PLIF, and the combined procedure is a safe and reliable treatment method for lumbar spondylolisthesis.

Antiobesity effect of MK-5046, a novel bombesin receptor subtype-3 agonist.

Bombesin receptor subtype-3 (BRS-3) is an orphan G protein-coupled receptor implicated in the regulation of energy homeostasis. Here, we report the biologic effects of a highly optimized BRS-3 agonist, (2S)-1,1,1-trifluoro-2-[4-(1H-pyrazol-1-yl)phenyl]-3-(4-{[1-(trifluoromethyl)cyclopropyl]methyl}-1H-imidazol-2-yl)propan-2-ol (MK-5046). Single oral doses of MK-5046 inhibited 2-h and overnight food intake and increased fasting metabolic rate in wild-type but not Brs3 knockout mice. Upon dosing for 14 days, MK-5046 at 25 mg · kg(-1) · day(-1) reduced body weight of diet-induced obese mouse by 9% compared with vehicle-dosed controls. In mice, 50% brain receptor occupancy was achieved at a plasma concentration of 0.34 ± 0.23 µM. With chronic dosing, effects on metabolic rate, rather than food intake, seem to be the predominant mechanism for weight reduction by MK-5046. The compound also effectively reduced body weight in rats and caused modest increases in body temperature, heart rate, and blood pressure. These latter effects on temperature, heart rate, and blood pressure were transient in nature and desensitized with continued dosing. MK-5046 is the first BRS-3 agonist with properties suitable for use in larger mammals. In dogs, MK-5046 treatment produced statistically significant and persistent weight loss, which was initially accompanied by increases in body temperature and heart rate that abated with continued dosing. Our results demonstrate antiobesity efficacy for MK-5046 in rodents and dogs and further support BRS-3 agonism as a new approach to the treatment of obesity.

Pyridinesulfonylureas and pyridinesulfonamides as selective bombesin receptor subtype-3 (BRS-3) agonists.

Bombesin receptor subtype-3 (BRS-3) is an orphan G-protein coupled receptor belonging to the subfamily of bombesin-like receptors. BRS-3 is implicated in the development of obesity and diabetes. We report here small-molecule agonists that are based on a 4-(alkylamino)pyridine-3-sulfonamide core. We describe the discovery of 2a, which has mid-nanomolar potency, selectivity for human BRS-3 versus the other bombesin-like receptors, and good bioavailability.

Small molecule insulin mimetics reduce food intake and body weight and prevent development of obesity.

Obesity and insulin resistance are major risk factors for a number of metabolic disorders, such as type 2 diabetes mellitus. Insulin has been suggested to function as one of the adiposity signals to the brain for modulation of energy balance. Administration of insulin into the brain reduces food intake and body weight, and mice with a genetic deletion of neuronal insulin receptors are hyperphagic and obese. However, insulin is also an anabolic factor; when administered systemically, pharmacological levels of insulin are associated with body weight gain in patients. In this study, we investigated the efficacy and feasibility of small molecule insulin mimetic compounds to regulate key parameters of energy homeostasis. Central intracerebroventricular (i.c.v.) administration of an insulin mimetic resulted in a dose-dependent reduction of food intake and body weight in rats, and altered the expression of hypothalamic genes known to regulate food intake and body weight. Oral administration of a mimetic in a mouse model of high-fat diet-induced obesity reduced body weight gain, adiposity and insulin resistance. Thus, insulin mimetics have a unique advantage over insulin in the control of body weight and hold potential as a novel anti-obesity treatment.

Body temperature as a mouse pharmacodynamic response to bombesin receptor subtype-3 agonists and other potential obesity treatments.

Treatment of rodents with a bombesin receptor subtype-3 (BRS-3) agonist reduces food intake and increases fasting metabolic rate, causing weight loss with continued treatment. In small mammals, core body temperature (T(b)) is regulated in part by nutritional status, with a reduced T(b) during fasting. We report that fed Brs3 knockout mice have a lower T(b), which is discordant with their nutritional status. Treatment of wild-type mice with a BRS-3 agonist increased T(b), more so when the baseline T(b) was reduced such as by fasting or during the inactive phase of the light cycle. With repeated BRS-3 agonist dosing, the T(b) increase attenuated despite continued weight loss efficacy. The increase in T(b) was not prevented by inhibitors of prostaglandin E (PGE) production but was partially reduced by a ß-adrenergic blocker. These results demonstrate that BRS-3 has a role in body temperature regulation, presumably secondary to its effect on energy metabolism, including effects on sympathetic tone. By making use of this phenomenon, the reversal of the fasting T(b) reduction was developed into a sensitive single-dose pharmacodynamic assay for BRS-3 agonism and other antiobesity compounds acting by various mechanisms, including sibutramine, cannabinoid-1, and melanin-concentrating hormone-1 receptor blockers, and melanocortin, ß3-adrenergic, and cholecystokinin-1 receptor agonists. These drugs increased both the fasted T(b) and the fasted, resting metabolic rates. The T(b) assay is a robust, information-rich assay that is simpler and has a greater throughput than measuring metabolic rate and is a practical, effective tool for drug discovery.

Synthesis and SAR of heterocyclic carboxylic acid isosteres based on 2-biarylethylimidazole as bombesin receptor subtype-3 (BRS-3) agonists for the treatment of obesity.

SAR around non-peptidic potent bombesin receptor subtype-3 (BRS-3) agonist lead 2 is presented. Attempts to replace the carboxylic acid with heterocyclic isosteres to improve oral bioavailability and brain penetration are described.

Synthesis and SAR of derivatives based on 2-biarylethylimidazole as bombesin receptor subtype-3 (BRS-3) agonists for the treatment of obesity.

This Letter describes a series of potent and selective BRS-3 agonists containing a biarylethylimidazole pharmacophore. Extensive SAR studies were carried out with different aryl substitutions. This work led to the identification of a compound 2-{2-[4-(pyridin-2-yl)phenyl]ethyl}-5-(2,2-dimethylbutyl)-1H-imidazole 9 with excellent binding affinity (IC(50)=18 nM, hBRS-3) and functional agonist activity (EC(50)=47 nM, 99% activation). After oral administration, compound 9 had sufficient exposure in diet induced obese mice to demonstrate efficacy in lowering food intake and body weight via BRS-3 activation.

Discovery of substituted biphenyl imidazoles as potent, bioavailable bombesin receptor subtype-3 agonists.

We report SAR studies on a novel non-peptidic bombesin receptor subtype-3 (BRS-3) agonist lead series derived from high-throughput screening hit RY-337. This effort led to the discovery of compound 22e with significantly improved potency at both rodent and human BRS-3.

Cis-2-dodecenoic Acid Mediates Its Synergistic Effect with Triazoles by Interfering with Efflux Pumps in Fluconazole-resistant Candida albicans.

OBJECTIVE: To evaluate the synergy of the Burkholderia signaling molecule cis-2-dodecenoic acid (BDSF) and fluconazole (FLU) or itraconazole (ITRA) against two azole-resistant C. albicans clinical isolates in vitro and in vivo. METHODS: Minimum inhibitory concentrations (MICs) of antibiotics against two azole-resistant C. albicans were measured by the checkerboard technique, E-test, and time-kill assay. In vivo antifungal synergy testing was performed on mice. Analysis of the relative gene expression levels of the strains was conducted by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). RESULTS: BDSF showed highly synergistic effects in combination with FLU or ITRA with a fractional inhibitory concentration index of ⪕ 0.08. BDSF was not cytotoxic to normal human foreskin fibroblast cells at concentrations of up to 300 µg/mL. The qRT-PCR results showed that the combination of BDSF and FLU/ITRA significantly inhibits the expression of the efflux pump genes CDR1 and MDR1 via suppression of the transcription factors TAC1 and MRR1, respectively, when compared with FLU or ITRA alone. No dramatic difference in the mRNA expression levels of ERG1, ERG11, and UPC2 was found, which indicates that the drug combinations do not significantly interfere with UPC2-mediated ergosterol levels. In vivo experiments revealed that combination therapy can be an effective therapeutic approach to treat candidiasis. CONCLUSION: The synergistic effects of BDSF and azoles may be useful as an alternative approach to control azole-resistant Candida infections.

Design and synthesis of (ant)-agonists that alter appetite and adiposity.

Over the past decade, hypothalamic circuits have been described that impact energy homeostasis in rodents and humans. Our drug development efforts for the treatment of obesity and the metabolic syndrome have largely focused on selected genetic and/or pharmacologically validated pathways. The translation of these pathways into therapeutics for the treatment of obesity will find its first clinical successes over the coming decade. Initial efforts have focused on gaining a better understanding of the relevance of rodent pharmacological and genetic observations for the development of therapeutics for the treatment of human obesity. We pursue pathways defined by the expression of the ghrelin receptor, melanin-concentrating hormone receptors, melanocortin receptors, cannabinoid receptors and neuropeptide Y1 and Y5 receptors. In this review, we will discuss drug development efforts for the treatment of obesity, focused on selective melanocortin 4 receptor agonists and neuropeptide Y1 and Y5 receptor antagonists. These drug development efforts required an in-depth understanding of cell-based observations which drive the development of compound structure-activity relationships. These include understanding of receptor function in selected cell-based backgrounds and early evaluation and validation of ex vivo observations in appropriate in vivo models. In order to develop selective and safe anti-obesity drugs, diverse approaches are needed to increase the likelihood of clinical success, including: (i) developing a detailed understanding of the predictive value of rodent pathways for treatment of human disease; (ii) knowledge of the exact location of targeted receptor subtypes for the clinical indication under study in order to derive a suitable compound profile; (iii) predictive measures of in vivo and/or ex vivo receptor occupancy required to bring about a desired physiological effect; (iv) predictive parameters that outline that the drug-derived effects are safe and mechanism-based; and (v) the refinement of selected compound classes, aimed at their clinical use.

Single Port Transumbilical Laparoscopic Surgery versus Conventional Laparoscopic Surgery for Benign Adnexal Masses: A Retrospective Study of Feasibility and Safety.

BACKGROUND: Single port laparoscopic surgery (SPLS) is an innovative approach that is rapidly gaining recognition worldwide. The aim of this study was to determine the feasibility and safety of SPLS compared to conventional laparoscopic surgery for the treatment of benign adnexal masses. METHODS: In total, 99 patients who underwent SPLS for benign adnexal masses between December 2013 and March 2015 were compared to a nonrandomized control group comprising 104 conventional laparoscopic adnexal surgeries that were performed during the same period. We retrospectively analyzed multiple clinical characteristics and operative outcomes of all the patients, including age, body mass index, size and pathological type of ovarian mass, operative time, estimated blood loss (EBL), duration of postoperative hospital stay, etc. RESULTS: No significant difference was observed between the two groups regarding preoperative baseline characteristics. However, the pathological results between the two groups were found to be slightly different. The most common pathological type in the SPLS group was mature cystic teratoma, whereas endometrioma was more commonly seen in the control group. Otherwise, the two groups had comparable surgical outcomes, including the median operation time (51 min vs. 52 min, P = 0.909), the median decreased level of hemoglobin from preoperation to postoperation day 3 (10 g/L vs. 10 g/L, P = 0.795), and the median duration of postoperative hospital stay (3 days vs. 3 days, P = 0.168). In SPLS groups, the median EBL and the anal exsufflation time were significantly less than those of the conventional group (5 ml vs. 10 ml, P < 0.001; 10 h vs. 22 h, P < 0.001). CONCLUSIONS: SPLS is a feasible and safe approach for the treatment of benign adnexal masses. Further study is required to better determine whether SPLS has significant benefits compared to conventional techniques.

Correlation between Cyr61 expression and clinicopathologic parameters in adenomyosis.

Adenomyosis, a benign invasion of endometrium, is closely related to endometriosis. Cysteine-rich 61 (Cyr61), a protein present in all endometrial tissues and menstrual effluents, is known to be associated with endometriosis. However, its relation to adenomyosis has not been determined thus far. Therefore, here, we aimed to investigate the expression of Cyr61 protein in adenomyosis and determine the correlation between Cyr61 expression and clinicopathologic parameters in patients with adenomyosis. One hundred and twenty patients with histologically diagnosed adenomyosis, who underwent hysterectomy for non-endometrial disease were enrolled in this study. Patients were interviewed using a standard questionnaire consisting of sociodemographic characteristics and reproduction history. The severity of dysmenorrhea and menorrhagia was evaluated using the visual analogue scale (VAS) and pictorial blood-loss assessment chart (PBAC). Samples of serum, endometrial tissue, and peritoneal fluid were collected, and Cyr61 mRNA levels were determined by RT-PCR. The Cyr61 protein levels in endometrial and ectopic lesions were determined by immunohistochemistry and those in serum and peritoneal fluid, by ELISA. We found that expression of Cyr61 was higher in the ectopic endometrium than in the eutopic endometrium. Cyr61 expression in the endometrium was correlated with age, number of natural labors, PBAC score, VAS score, uterine volume, adenomyosis type, and concurrent endometriosis. The Cyr61 protein level in the ascites was higher than that in serum, and no correlation existed between them. Our results suggest that the expression of Cyr61 may be indirectly related to the degree of dysmenorrhea and Cyr61 may be involved in the pathogenesis of adenomyosis.

Alpha-melanocyte-stimulating hormone stimulates oxytocin release from the dendrites of hypothalamic neurons while inhibiting oxytocin release from their terminals in the neurohypophysis.

The peptides alpha-melanocyte stimulating hormone (alpha-MSH) and oxytocin, when administered centrally, produce similar behavioral effects. alpha-MSH induces Fos expression in supraoptic oxytocin neurons, and alpha-MSH melanocortin-4 receptors (MC4Rs) are highly expressed in the supraoptic nucleus, suggesting that alpha-MSH and oxytocin actions are not independent. Here we investigated the effects of alpha-MSH on the activity of supraoptic neurons. We confirmed that alpha-MSH induces Fos expression in the supraoptic nucleus when injected centrally and demonstrated that alpha-MSH also stimulates Fos expression in the nucleus when applied locally by retrodialysis. Thus alpha-MSH-induced Fos expression is not associated with electrophysiological excitation of supraoptic neurons because central injection of alpha-MSH or selective MC4 receptor agonists inhibited the electrical activity of oxytocin neurons in the supraoptic nucleus recorded in vivo. Consistent with these observations, oxytocin secretion into the bloodstream decreased after central injection of alpha-MSH. However, MC4R ligands induced substantial release of oxytocin from dendrites in isolated supraoptic nuclei. Because dendritic oxytocin release can be triggered by changes in [Ca2+]i, we measured [Ca2+]i responses in isolated supraoptic neurons and found that MC4R ligands induce a transient [Ca2+]i increase in oxytocin neurons. This response was still observed in low extracellular Ca2+ concentration and probably reflects mobilization of [Ca2+]i from intracellular stores rather than entry via voltage-gated channels. Taken together, these results show for the first time that a peptide, here alpha-MSH, can induce differential regulation of dendritic release and systemic secretion of oxytocin, accompanied by dissociation of Fos expression and electrical activity.

Increased melanin concentrating hormone receptor type I in the human hypothalamic infundibular nucleus in cachexia.

Melanin-concentrating hormone (MCH) exerts a positive regulation on appetite and binds to the G protein-coupled receptors, MCH1R and MCH2R. In rodents, MCH is produced by neurons in the lateral hypothalamus with projections to various hypothalamic and other brain sites. In the present study, MCH1R was shown, by immunocytochemistry, to be present in the human infundibular nucleus/median eminence, paraventricular nucleus, lateral hypothalamic area, and perifornical area, although in the latter two regions, only a few MCH1R-containing cells were found. In addition, MCH1R staining was found in nerve fibers in the periventricular nucleus, dorsomedial and ventromedial nucleus, suprachiasmatic nucleus, and tuberomammillary nucleus. A significant 1.6 times increase in the number of MCH1R cell body staining was found in the infundibular nucleus in postmortem brain material of cachectic patients, compared with matched controls, supporting a role for this receptor in energy homeostasis in the human.

Identification of differential genes in ovarian cancer using representational difference analysis of cDNA.

OBJECTIVE: To identify differential genes between normal ovarian epithelium tissue and ovarian epithelial cancer using representational difference analysis of cDNA (cDNA-RDA). METHODS: cDNA-RDA was performed to identify the differentially expressed sequences between cDNAs from cancer tissue and cDNAs from normal ovarian tissue in the same patient who was in the early stage of ovarian serous cystadenocarcinoma. These differentially expressed fragments were cloned and analyzed, then sequenced and compared with known genes. RESULTS: Three differentially expressed cDNA fragments were isolated using cDNA from normal ovarian tissue as tester and cDNA from cancer tissue as driver amplicon by cDNA-RDA. DP III-1 and DP III-2 cDNA clone showed significant homology to the cDNA of alpha actin gene; DP III-3 cDNA clone showed significant homology to the cDNA of transgelin gene. CONCLUSION: cDNA-RDA can be used to sensitively identify the differentially expressed genes in ovarian serous cystadenocarcinoma. Ovarian serous cystadenocarcinoma involves alteration of multiple genes.

Two-stage resection of a disseminated mixed endometrial stromal sarcoma and smooth muscle tumor with intravascular and intracardiac extension.

OBJECTIVE: Mixed endometrial stromal and smooth muscle tumor (MESSMT)-a rare mesenchymal uterine tumor of the uterus with atypical clinical symptoms-is susceptible to misdiagnosis and missed diagnosis. We report a case of a disseminated MESSMT with intravenous and intracardiac extensions treated with staging surgery and review previously documented cases of such tumors with intracardiac extension. CASE REPORT: The case involves a 45-year-old woman with disseminated MESSMT that originated in the uterus and progressed through the iliac vein, inferior vena cava, right atrium, and into the right ventricle, which closely resembled intravenous leiomyomatosis (IVL) grossly and microscopically. She presented with a 1-year history of dyspnea on exertion. IVL was highly suspected preoperatively based on computed tomography and magnetic resonance imaging findings. Two-stage surgeries were performed successfully. The postoperative pathology indicated a disseminated MESSMT. CONCLUSION: This case illustrates the important role of pathology and immunohistochemistry in the differential diagnosis of a rare tumor that mimics the characteristics of IVL with intracardiac involvement and demonstrates the therapeutic strategy for this rare entity.

Small-molecule insulin mimetic reduces hyperglycemia and obesity in a nongenetic mouse model of type 2 diabetes.

Adiposity positively correlates with insulin resistance and is a major risk factor of type 2 diabetes. Administration of exogenous insulin, which acts as an anabolic factor, facilitates adipogenesis. Recently nonpeptidal insulin receptor (IR) activators have been discovered. Here we evaluate the effects of the orally bioavailable small-molecule IR activator (Compound-2) on metabolic abnormalities associated with type 2 diabetes using a nongenetic mouse model in comparison with the effects of a novel non-thiazolidinedione (nTZD) peroxisome proliferator-activated receptor-gamma agonist. Both Compound-2 and nTZD alleviated fasting and postprandial hyperglycemia; accelerated glucose clearance rate; and normalized plasma levels of nonesterified fatty acids, triglycerides, and leptin. Unlike nTZD, which increased body weight gain, and total fat mass, which is a common feature for PPARgamma agonists, Compound-2 prevented body weight gain and hypertrophy of brown, and white adipose tissue depots and the development of hepatic steatosis in the mouse model of type 2 diabetes. The effect of the two compounds on proximal steps in insulin signal transduction pathway was analyzed in tissues. Compound-2 enhanced insulin-stimulated phosphorylation of IR tyrosine and/or Akt in the liver, skeletal muscle, and white adipose tissue, whereas nTZD potentiated the phosphorylation of IR and Akt in the adipose tissue only. In conclusion, small-molecule IR activators have unique features as insulin sensitizers and hold potential utility in the treatment of type 2 diabetes and obesity.

Exploring the site of anorectic action of peripherally administered synthetic melanocortin peptide MT-II in rats.

Melanotan-II (MT-II), a cyclic heptapeptide, is a potent, non-selective melanocortinergic agonist. When administered centrally or systemically, MT-II elicited a profound inhibitory effect on food intake in rodents, presumably via activation of melanocortin-4-receptor (MC4R). In this study, we sought to investigate whether penetration of MT-II and iodo-MT-II into brain parenchyma is required for the anorectic effect following intravenous (IV) administration. Firstly, both MT-II and iodo-MT-II were effective at suppressing appetite in rats following their IV administration. We next surveyed by in vitro autoradiographic studies the distribution of selective (125)I-MT-II binding sites in multiple brain regions including areas important for feeding regulation such as the hypothalamus and caudal brainstem. Upon IV administration of (125)I-MT-II, significant radioactivity could not be detected in various brain regions by autoradiography except for a group of circumventricular organs (CVOs), which are anatomically situated outside the blood-brain barrier (BBB). The most intensely labeled CVOs include the subfornical organ, median eminence, area postrema and choroid plexus, and accumulation of radioactivity at these sites can be blocked by co-injection of excess unlabeled MT-II. Direct measurement of MT-II in the brain and plasma by LC-MS-MS following IV injection confirmed that the degree of MT-II penetration into the brain is negligible. Furthermore, when given peripherally under conditions that suppressed food intake, MT-II did not result in a detectable induction of c-Fos-like immunoreactivity in brain regions where a significantly elevated c-Fos expression was observed following intracerebroventricular injection of this peptide. Our results indicate that MT-II has a very limited brain penetration capability, and its effect on feeding behavior following systemic administration may be mediated by either the brain regions in close proximity to the CVOs or sites outside of the BBB, including CVOs or other peripheral systems.