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N Mohammadi E, Louwies T, Pietra C, Northrup SR, Greenwood-Van Meerveld B. Attenuation of Visceral and Somatic Nociception by Ghrelin Mimetics. J Exp Pharmacol 2020; 12:267-274. [PMID: 32801950 PMCID: PMC7415447 DOI: 10.2147/jep.s249747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/10/2020] [Indexed: 02/05/2023] Open
Abstract
Purpose The anti-nociceptive properties of ghrelin have been demonstrated in alleviating inflammatory and neuropathic pain. Whether a ghrelin receptor-mediated mechanism attenuates visceral and somatic pain in the absence of active inflammation remains to be explored. Here, we investigate the efficacy of peripherally restricted (ipamorelin) and a globally active (HM01) selective ghrelin receptor agonist in an experimental model of non-inflammatory visceral hypersensitivity and somatic mechanical allodynia. Materials and Methods Visceral hypersensitivity was induced by dilute acetic acid (0.6%) infusion in the colon of rats in the absence of colonic epithelial inflammation. Ghrelin mimetics HM01 and ipamorelin were administered orally or intravenously, respectively. The ghrelin receptor antagonist H0900 was administered orally. Colonic sensitivity was assessed via a visceromotor behavioral response (VMR) quantified as the number of abdominal contractions in response to graded isobaric pressures (0-60 mmHg) of colorectal distension (CRD). Somatic mechanical allodynia was quantified by the number of ipsilateral paw withdrawals in response to a calibrated von Frey filament. Results Compared to vehicle controls, ghrelin mimetics HM01 and ipamorelin significantly attenuated colonic hypersensitivity and somatic allodynia. The anti-nociceptive effects of the ghrelin mimetics were blocked after administration of the ghrelin receptor antagonist H0900. Conclusion We have shown that ghrelin receptor-mediated mechanisms are involved in visceral and somatic hypersensitivity in the absence of active colonic inflammation. Furthermore, visceral and somatic hypersensitivity could be attenuated by a peripherally restricted ghrelin mimetic. These results highlight a potential novel approach for treating acute visceral and somatic pain by ghrelin mimetics.
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Affiliation(s)
- Ehsan N Mohammadi
- Oklahoma Center for Neuroscience, Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Tijs Louwies
- Oklahoma Center for Neuroscience, Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | | | | | - Beverley Greenwood-Van Meerveld
- Oklahoma Center for Neuroscience, Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
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Sinha DK, Balasubramanian A, Tatem AJ, Rivera-Mirabal J, Yu J, Kovac J, Pastuszak AW, Lipshultz LI. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Transl Androl Urol 2020; 9:S149-S159. [PMID: 32257855 PMCID: PMC7108996 DOI: 10.21037/tau.2019.11.30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Male hypogonadism is an increasingly prevalent clinical condition that affects patients’ quality of life and overall health. Obesity and metabolic syndrome can both cause and result from hypogonadism. Although testosterone remains the gold standard for hypogonadism management, its benefits are not always conserved across different populations, especially with regards to changes in body composition. Partially in response to this, growth hormone secretagogues (GHS) have emerged as a potential novel adjunctive therapy for some of the symptoms of hypogonadism, although current data on their clinical efficacy largely remain lacking. The present review examines the existing literature on the use of GHS and explores their potential complementary role in the management of hypogonadal and eugonadal males with metabolic syndrome or subclinical hypogonadism (SH). The GHS that will be discussed include sermorelin, growth hormone-releasing peptides (GHRP)-2, GHRP-6, ibutamoren, and ipamorelin. All are potent GH and IGF-1 stimulators that can significantly improve body composition while ameliorating specific hypogonadal symptoms including fat gain and muscular atrophy. However, a paucity of data examining the clinical effects of these compounds currently limits our understanding of GHS’ role in the treatment of men with hypogonadism, but does open opportunities for future investigation.
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Affiliation(s)
| | | | | | | | - Justin Yu
- Baylor College of Medicine, Houston, TX, USA
| | - Jason Kovac
- Men's Health Center, Urology of Indiana, Greenwood, IN, USA
| | - Alexander W Pastuszak
- Division of Urology, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Larry I Lipshultz
- Scott Department of Urology, Baylor College of Medicine, Houston, TX, USA.,Center for Reproductive Medicine, Baylor College of Medicine, Houston, TX, USA
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Mohammadi EN, Pietra C, Giuliano C, Fugang L, Greenwood-Van Meerveld B. A Comparison of the Central versus Peripheral Gastrointestinal Prokinetic Activity of Two Novel Ghrelin Mimetics. J Pharmacol Exp Ther 2018; 368:116-124. [PMID: 30377215 DOI: 10.1124/jpet.118.250738] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/10/2018] [Indexed: 12/30/2022] Open
Abstract
The gastrointestinal (GI) prokinetic effects of ghrelin occur through direct peripheral effects on ghrelin receptors within the enteric nervous system and via the ghrelin receptor on the vagus nerve, which activate a centrally mediated mechanism. However, the relative contribution of peripheral versus central effects to the overall prokinetic effect of ghrelin agonists requires further investigation. Here, we investigated the central versus peripheral prokinetic effect of ghrelin by using two novel ghrelin agonists: HM01 (N'-[(1S)-1-(2,3-dichloro-4-methoxyphenyl)ethyl]-N-methyl-N-[1,3,3-trimethyl-(4R)-piperidyl]-urea HCL) with high brain penetration compared with HM02 (N'-[(1S)-1-(2,3-dichloro-4-methoxyphenyl)ethyl]-N-hydroxy-N-(1-methyl-4-piperidinyl)-urea), a more peripherally acting ghrelin agonist. The pharmacokinetic profiles of both ghrelin agonists were evaluated after intravenous and oral administration in rats. The efficacy of HM01 and HM02 was assessed in a rat model of postoperative ileus (POI) induced by abdominal surgery and in a rodent defecation assay. Pharmacokinetic results in our models confirmed that HM01, but not HM02, was a brain-penetrant ghrelin agonist. Administration of either HM01 or HM02 reversed the delayed upper and lower gastrointestinal transit induced by abdominal surgery to levels resembling the non-POI controls. In the defecation test, HM01, but not HM02, significantly increased the weight of fecal pellets. Our findings suggest that, in a rodent model of POI, synthetic ghrelin agonists stimulate GI transit through a peripheral site of action. However, in the defecation assay, our data suggest that a ghrelin-mediated mechanism is located at a central site. Taken together, a ghrelin agonist with both central and peripheral prokinetic activity may show therapeutic potential to treat delayed GI transit disorders.
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Affiliation(s)
- Ehsan N Mohammadi
- Oklahoma Center for Neuroscience (E.N.M., B.G.-V.M.), Department of Physiology (B.G.-V.M.), and VA Medical Center (B.G.-V.M.), University of Oklahoma Health Science Center, Oklahoma City, Oklahoma; HDB Biosciences Co. Ltd., Shanghai, People's Republic of China (L.F.); and Helsinn Healthcare SA, RPD Department, Lugano, Switzerland (C.P., C.G.)
| | - Claudio Pietra
- Oklahoma Center for Neuroscience (E.N.M., B.G.-V.M.), Department of Physiology (B.G.-V.M.), and VA Medical Center (B.G.-V.M.), University of Oklahoma Health Science Center, Oklahoma City, Oklahoma; HDB Biosciences Co. Ltd., Shanghai, People's Republic of China (L.F.); and Helsinn Healthcare SA, RPD Department, Lugano, Switzerland (C.P., C.G.)
| | - Claudio Giuliano
- Oklahoma Center for Neuroscience (E.N.M., B.G.-V.M.), Department of Physiology (B.G.-V.M.), and VA Medical Center (B.G.-V.M.), University of Oklahoma Health Science Center, Oklahoma City, Oklahoma; HDB Biosciences Co. Ltd., Shanghai, People's Republic of China (L.F.); and Helsinn Healthcare SA, RPD Department, Lugano, Switzerland (C.P., C.G.)
| | - Li Fugang
- Oklahoma Center for Neuroscience (E.N.M., B.G.-V.M.), Department of Physiology (B.G.-V.M.), and VA Medical Center (B.G.-V.M.), University of Oklahoma Health Science Center, Oklahoma City, Oklahoma; HDB Biosciences Co. Ltd., Shanghai, People's Republic of China (L.F.); and Helsinn Healthcare SA, RPD Department, Lugano, Switzerland (C.P., C.G.)
| | - Beverley Greenwood-Van Meerveld
- Oklahoma Center for Neuroscience (E.N.M., B.G.-V.M.), Department of Physiology (B.G.-V.M.), and VA Medical Center (B.G.-V.M.), University of Oklahoma Health Science Center, Oklahoma City, Oklahoma; HDB Biosciences Co. Ltd., Shanghai, People's Republic of China (L.F.); and Helsinn Healthcare SA, RPD Department, Lugano, Switzerland (C.P., C.G.)
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