Contents lists available at ScienceDirect Progress in Neuropsychopharmacology & Biological Psychiatry journal homepage: www.elsevier.com/locate/pnp Carbamoylated erythropoietin produces antidepressant-like effects in male and female mice Dayalan Sampath a,b , Joshua McWhirt a , Monica Sathyanesan a,b , Samuel S. Newton a,b, ⁎ a Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069, United States of America b Sioux Falls VA Healthcare System, Sioux Falls, SD 57105, United States of America ARTICLE INFO Keywords: Carbamoylated erythropoietin Behavioral despair Antidepressant mechanism of action Phosphorylated CREB ABSTRACT Major depressive disorder and related illnesses are globally prevalent, with a significant risk for suicidality if untreated. Antidepressant drugs that are currently prescribed do not benefit 30% of treated individuals. Furthermore, there is a delay of 3 or more weeks before a reduction in symptoms. Results from preclinical studies have indicated an important role for trophic factors in regulating behavior. Erythropoietin (Epo), which is widely prescribed for anemia, has been shown to produce robust neurotrophic actions in the CNS. Although Epo's antidepressant activity has been successfully demonstrated in multiple clinical trials, the inherent ability to elevate RBC counts and other hematological parameters preclude its development as a mainstream CNS drug. A chemically engineered derivative, carbamoylated Epo (Cepo) has no hematological activity, but retains the neurotrophic actions of Epo. Cepo is therefore an attractive candidate to be tested as an antidepressant. Objective: To evaluate the antidepressant properties of Cepo in established antidepressant-responsive rodent behavioral assays. Methods: Adult male and female BALB/c mice were used for this study. Cepo (30 μgrams/ kg BWT) or vehicle (PBS) was administered intraperitoneally for 4 days before the test of novelty induced hypo- phagia and subsequently at five hours before testing in forced swim test (FST), tail suspension test (TST) and open field test (OFT). To obtain mechanistic insight we examined the phosphorylation of the transcription factor cAMP response element binding protein (CREB). Results: Administration of Cepo at 30 μgrams/ kg BWT, for 4 days produced significant reduction in latency to consume a palatable drink in a novel environment in male and female mice. Male BALB/c mice had a significant reduction in immobility in both tail suspension and forced swim tests, and female mice exhibited lower im- mobility in the forced swim test. 1. Introduction Major Depressive disorder is a widely prevalent and debilitating mental health illness with about 20.6% of people suffering from it (Hasin et al., 2018). Despite substantial gains in increasing disease awareness and treatment initiatives, currently prescribed anti- depressant drugs are effective in only 60% of treated individuals. The most widely used drugs continue to be those that were designed to elevate synaptic monoamine levels. Although there has been significant progress in understanding depression neurobiology, such as the im- portant role of neurotrophic factors in the antidepressant activity (Duman et al., 1997, translating these findings to the clinic has been slow. The challenges include development of neurotrophic molecules as drugs, penetration across the blood brain barrier, and unknown clinical safety profile. In this context, it is interesting to note that erythropoietin (Epo) which is widely prescribed to treat anemia, has emerged as a clinically relevant neurotrophic molecule (Miskowiak et al., 2012). Epo's known safety profile has facilitated multiple clinical trials testing it for antidepressant activity (Miskowiak et al., 2007; Miskowiak et al., 2014; Miskowiak et al., 2015). While the results are promising, the potent erythropoeitic activity inherent to Epo is likely to hamper its development as a viable antidepressant drug (Coleman et al., 2006; Ehrenreich et al., 2009). The discovery that Epo can be chemically modified via an in vitro post-translational modification, carbamoylation, to render it non-ery- thropoeitic enabled the field to address the hematological side effect limitations of Epo (Leist et al., 2004). Carbamoylated Epo (Cepo) re- tains neurotrophic and neuroprotective activity but is devoid of https://doi.org/10.1016/j.pnpbp.2019.109754 Received 13 March 2019; Received in revised form 25 July 2019; Accepted 23 August 2019 ⁎ Corresponding author at: Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069, United States of America. E-mail addresses: dayalan.sampath@usd.edu (D. Sampath), Joshua.McWhirt@usd.edu (J. McWhirt), Monica.Sathyanesan@usd.edu (M. Sathyanesan), Samuel.Sathyanesan@usd.edu (S.S. Newton). Progress in Neuropsychopharmacology & Biological Psychiatry 96 (2020) 109754 Available online 24 August 2019 0278-5846/ © 2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/). T