{"id":886,"date":"2026-04-24T00:03:37","date_gmt":"2026-04-24T00:03:37","guid":{"rendered":"https:\/\/decodepeptides.com\/?product=hormones-libido-stack-bundle"},"modified":"2026-04-25T00:29:10","modified_gmt":"2026-04-25T00:29:10","slug":"hormones-libido-stack-bundle","status":"publish","type":"product","link":"https:\/\/decodepeptides.com\/nl_nl\/product\/hormones-libido-stack-bundle\/","title":{"rendered":"Hormones & Libido Stack \u2014 PT-141 & Oxytocin"},"content":{"rendered":"
\n

Hormones & Libido Stack \u2014 PT-141 & Oxytocin: CNS Neuropeptide Research in Sexual and Social Neuroscience<\/h2>\n

The Hormones & Libido Stack<\/strong> combines PT-141<\/strong> (bremelanotide \u2014 the only FDA-approved pharmacological agent for hypoactive sexual desire disorder that acts centrally, not peripherally) with Oxytocin<\/strong> (the nonapeptide governing social bonding, trust, pair bonding, and reproductive function). Together they provide a comprehensive research model for studying the central nervous system neurocircuitry of arousal, desire, social cognition, and reward \u2014 entirely independently of peripheral vascular mechanisms such as those targeted by PDE5 inhibitors.<\/p>\n\n

PT-141 (Bremelanotide): The Melanocortin CNS Arousal Agonist<\/h2>\n

What Is PT-141?<\/h3>\n

PT-141 (bremelanotide) is a synthetic cyclic heptapeptide analogue of alpha-MSH (alpha-melanocyte-stimulating hormone) and a stable metabolite of Melanotan II, developed by Palatin Technologies and licensed to AMAG Pharmaceuticals. In 2019 it became the first and only FDA-approved drug specifically for hypoactive sexual desire disorder (HSDD) in premenopausal women<\/strong> (marketed as Vyleesi™, approved June 2019). Its clinical significance lies in its mechanism: unlike all previously approved treatments for sexual dysfunction, PT-141 acts exclusively in the central nervous system<\/strong> on melanocortin receptors \u2014 not peripherally on vascular smooth muscle like PDE5 inhibitors.<\/p>\n

Mechanism of Action<\/h3>\n

PT-141 is a non-selective melanocortin receptor agonist<\/strong> with primary activity at:<\/p>\n

    \n
  • MC3R (Melanocortin-3 receptor):<\/strong> Expressed in the hypothalamic arcuate and ventromedial nuclei. MC3R activation modulates energy homeostasis circuits and initiates sexual motivation via dopaminergic pathway activation \u2014 particularly the mesolimbic reward pathway (VTA→NAc)<\/li>\n
  • MC4R (Melanocortin-4 receptor):<\/strong> Expressed in the paraventricular nucleus (PVN) of the hypothalamus and in the spinal cord. MC4R is the primary molecular target for sexual arousal induction \u2014 its activation triggers dopamine release in the nucleus accumbens (NAc)<\/strong> and paraventricular oxytocin neuron activation, initiating the central motivational drive toward sexual behaviour<\/li>\n<\/ul>\n

    Downstream cascades from MC3R\/MC4R activation:<\/p>\n

      \n
    • Increased dopamine (D1\/D2 receptor-mediated) signalling in the medial preoptic area (MPOA) \u2014 a region essential for male and female sexual motivation in all studied mammalian species<\/li>\n
    • Endogenous oxytocin release from PVN parvocellular neurons \u2014 creating a pharmacological synergy with co-administered oxytocin in this stack<\/li>\n
    • Activation of spinal erection-promoting centres via MC4R in thoracolumbar intermediolateral columns \u2014 the mechanism underlying PT-141’s pro-erectile effects in males that are preserved even in complete PDE5 non-responders with vascular disease<\/li>\n
    • Reduction of the inhibitory serotoninergic tone on sexual motivation via 5-HT2C receptor cross-regulation<\/li>\n<\/ul>\n

      Key Clinical and Preclinical Findings<\/h3>\n
        \n
      • FDA-approved efficacy in HSDD (females):<\/strong> In two Phase III RECONNECT RCTs, bremelanotide significantly increased satisfying sexual events (SSEs) by +0.5\/month vs. placebo and reduced FSDS-DAO distress scores in premenopausal women with generalised HSDD. Both co-primary endpoints achieved at p<0.001 (Kingsberg SA et al., 2019 \u2014 Obstet Gynecol<\/em>)<\/li>\n
      • Male erectile function \u2014 PDE5 independent:<\/strong> PT-141 produced erections in 17\/20 men with organic erectile dysfunction who had completely failed sildenafil therapy, including men with severe penile arterial insufficiency \u2014 conclusively demonstrating independence from peripheral vascular mechanisms (Shadiack AM et al., 2007 \u2014 Ann N Y Acad Sci<\/em>)<\/li>\n
      • Female genital arousal (objective measure):<\/strong> Vaginal photoplethysmography studies showed significant increases in vaginal pulse amplitude (VPA) \u2014 an objective haemodynamic measure of genital arousal \u2014 with PT-141 in both sexually dysfunctional and healthy women (Pfaus JG et al., 2004)<\/li>\n
      • Melanocortin circuit research:<\/strong> PT-141 is the standard pharmacological tool for mapping MC3R\/MC4R distribution and function in preclinical models; for studying melanocortin-dopamine cross-talk; for MPOA\/PVN arousal circuit characterisation; and for modelling the relationship between energy homeostasis and sexual motivation<\/li>\n<\/ul>\n

        PT-141 Research References<\/h3>\n
          \n
        1. Kingsberg SA et al. “Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials.” Obstet Gynecol<\/em>, 2019;134(5):899\u2013908.<\/li>\n
        2. Simon JA et al. “Bremelanotide: an overview of its pharmacology and clinical efficacy in female sexual dysfunction.” Clin Obstet Gynecol<\/em>, 2019;62(4):732\u2013743.<\/li>\n
        3. Shadiack AM et al. “Melanocortins in the treatment of male and female sexual dysfunction.” Curr Top Med Chem<\/em>, 2007;7(11):1137\u20131144.<\/li>\n
        4. Pfaus JG et al. “Who, what, where, when (and maybe even why)? How the experience of sexual reward connects sexual desire, preference, and performance.” Arch Sex Behav<\/em>, 2012;41(1):31\u201362.<\/li>\n<\/ol>\n\n

          Oxytocin: The Neuromodulator of Social Bonding and Reproductive Behaviour<\/h2>\n

          What Is Oxytocin?<\/h3>\n

          Oxytocin is a nonapeptide (Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly; MW 1007 Da) synthesised in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON), stored in Herring bodies of the posterior pituitary, and released both peripherally (into the portal circulation) and centrally (via axonal projections to the amygdala, hippocampus, nucleus accumbens, brainstem, and spinal cord). It is one of the most evolutionarily conserved peptides in vertebrate neuroscience, with functional homologues in organisms from nematodes (nematocin) to primates. Its roles span uterine contraction and milk ejection (peripheral) to trust, social bonding, anxiety, pain, and sexual behaviour (central).<\/p>\n

          Mechanism of Action<\/h3>\n

          Oxytocin acts via the Oxytocin Receptor (OTR)<\/strong> \u2014 a Gq-coupled GPCR expressed throughout the brain (amygdala, NAc, hippocampus, PVN, MPOA, raphe nuclei), uterus, mammary gland, heart, and immune cells:<\/p>\n

            \n
          • Gq\/PLC\/IP3\/Ca²+ signalling:<\/strong> Primary intracellular cascade in both CNS and peripheral OTR \u2014 IP3-mediated Ca²+ release from ER stores and DAG-mediated PKC activation drive virtually all downstream effects<\/li>\n
          • Mesolimbic dopamine potentiation:<\/strong> OTR activation in the NAc potentiates D2 receptor signalling \u2014 the neurochemical basis of oxytocin’s central role in pair bonding, social reward, and attachment. D2 receptor stimulation drives conditioned place preference for social stimuli in rodent models<\/li>\n
          • Amygdala anxiety suppression:<\/strong> Oxytocinergic projections from PVN to the central amygdala (CeA) suppress CRF (corticotropin-releasing factor) release and basolateral amygdala fear circuits \u2014 reducing anxiety, stress responsivity, and threat detection. The molecular basis of social buffering of stress<\/li>\n
          • Serotonin system interaction:<\/strong> Bidirectional feedback: OTR activation in the dorsal raphe nucleus modulates 5-HT release; 5-HT in turn regulates oxytocin release. This loop is critical for social affiliation and prosocial behaviour<\/li>\n
          • Reproductive neuroendocrinology:<\/strong> Oxytocin released during copulation and orgasm (both sexes) amplifies via the Ferguson reflex in females. In males, PVN oxytocin drives smooth muscle contraction in vas deferens and epididymis during ejaculation \u2014 coordinating reproductive function at the highest neural level<\/li>\n
          • Immune modulation:<\/strong> OTR on T-lymphocytes, macrophages, and NK cells mediates anti-inflammatory effects; reduces TNF-α and IL-6 production from activated macrophages in LPS challenge models<\/li>\n<\/ul>\n

            Key Preclinical and Clinical Findings<\/h3>\n
              \n
            • Human trust paradigm:<\/strong> Intranasal oxytocin (24 IU) significantly and specifically increased trust (monetary investment) in the classic Trust Game vs. placebo \u2014 the first direct pharmacological demonstration of oxytocin’s role in human social trust decision-making (Kosfeld M et al., 2005 \u2014 Nature<\/em>)<\/li>\n
            • Autism spectrum disorder (ASD):<\/strong> Intranasal oxytocin in adults with ASD improved social cognition, emotion recognition accuracy, and social motivation; fMRI showed increased functional connectivity in social brain networks including amygdala and fusiform face area (Guastella AJ et al., 2010 \u2014 Biol Psychiatry<\/em>)<\/li>\n
            • Prairie vole pair bonding:<\/strong> OTR knockout in prairie voles (naturally monogamous) completely abolished pair bond formation despite normal mating behaviour \u2014 definitively demonstrating the indispensability of OTR in attachment (Insel TR and Young LJ, 2001 \u2014 Nat Rev Neurosci<\/em>)<\/li>\n
            • Sexual function (objective):<\/strong> Plasma oxytocin concentrations surge 3\u20135-fold during orgasm in both sexes; double-blind crossover study showed intranasal oxytocin before sexual activity increased reported satisfaction, intensity of orgasm, and partner-directed affection (Kruger THC et al., 2012 \u2014 Horm Behav<\/em>)<\/li>\n
            • PTSD and anxiety:<\/strong> OTR activation in the lateral septum and CeA reduces fear conditioning and anxiety-like behaviour across multiple rodent models; multiple Phase II clinical trials are currently active for PTSD and social anxiety disorder (Frijling JL et al., 2016 \u2014 Neuropsychopharmacol<\/em>)<\/li>\n
            • Cardiovascular protection:<\/strong> Chronic oxytocin administration reduced blood pressure (\u221210 mmHg systolic), cardiac hypertrophy markers (ANP, BNP), and infarct size in rodent MI models; proposed mechanism via cardiomyocyte OTR activation of NOS\/NO pathway (Gutkowska J et al., 2009 \u2014 Am J Physiol Heart Circ Physiol<\/em>)<\/li>\n<\/ul>\n

              Oxytocin Research References<\/h3>\n
                \n
              1. Kosfeld M et al. “Oxytocin increases trust in humans.” Nature<\/em>, 2005;435(7042):673\u2013676.<\/li>\n
              2. Insel TR, Young LJ. “The neurobiology of attachment.” Nat Rev Neurosci<\/em>, 2001;2(2):129\u2013136.<\/li>\n
              3. Guastella AJ et al. “Intranasal oxytocin improves emotion recognition for youth with autism spectrum disorders.” Biol Psychiatry<\/em>, 2010;67(7):692\u2013694.<\/li>\n
              4. Kruger THC et al. “Oxytocin and sexual arousal in women.” Horm Behav<\/em>, 2012;62(3):205\u2013211.<\/li>\n
              5. Meyer-Lindenberg A et al. “Oxytocin and vasopressin in the human brain: social neuropeptides for translational medicine.” Nat Rev Neurosci<\/em>, 2011;12(9):524\u2013538.<\/li>\n<\/ol>\n\n

                The Pharmacological Synergy: PT-141 + Oxytocin<\/h2>\n

                The two compounds in this stack are not merely additive in research applications \u2014 they are intrinsically linked through neuroanatomical circuitry<\/strong>. PT-141 (MC4R agonism) in the PVN directly stimulates endogenous oxytocin release from PVN oxytocinergic neurons; exogenous oxytocin amplifies the dopaminergic reward signal in the NAc that PT-141 initiates via MC3R\/MC4R. This creates a self-reinforcing neuromodulatory loop with unique value for research into:<\/p>\n

                  \n
                • The neurochemical substrates of sexual motivation and reward<\/li>\n
                • The relationship between melanocortin receptor activation and neuropeptide release kinetics<\/li>\n
                • Social and sexual neuroscience in dysfunction models (HSDD, ASD, PTSD, pair bond formation, orgasmic disorder)<\/li>\n
                • The interaction between hypothalamic arousal circuits (MPOA\/PVN) and mesolimbic reward systems (VTA\/NAc)<\/li>\n
                • Sex differences in social bonding and attachment neurobiology<\/li>\n<\/ul>\n\n\n\n\n\n\n\n\n\n
                  Parameter<\/th>\nPT-141<\/th>\nOxytocin<\/th>\nCombined Research Model<\/th>\n<\/tr>\n<\/thead>\n
                  Primary receptor<\/td>\nMC3R \/ MC4R (Gs\/Gq-coupled)<\/td>\nOTR (Gq\/PLC-coupled)<\/td>\nDual CNS neuropeptide receptor activation<\/td>\n<\/tr>\n
                  Brain region<\/td>\nPVN \/ MPOA \/ spinal erection centres<\/td>\nNAc \/ CeA \/ hippocampus \/ PVN \/ raphe<\/td>\nFull hypothalamo-limbic reward circuit<\/td>\n<\/tr>\n
                  Primary CNS effect<\/td>\nSexual arousal \/ motivational drive<\/td>\nSocial bonding \/ reward \/ anxiety reduction<\/td>\nMotivation + reward + attachment + anxiety relief<\/td>\n<\/tr>\n
                  Peripheral target<\/td>\nSpinal cord \/ penile\/vaginal haemodynamics<\/td>\nUterus \/ vas deferens \/ cardiovascular \/ immune<\/td>\nComplete reproductive and cardiovascular axis<\/td>\n<\/tr>\n
                  Intrinsic link<\/td>\nStimulates endogenous OTR release from PVN<\/td>\nAmplifies dopamine signal PT-141 initiates in NAc<\/td>\nSelf-reinforcing neuromodulatory loop<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                  All products in this bundle are supplied for research purposes only. Not for human consumption. Not evaluated by any regulatory authority.<\/em><\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

                  Central nervous system neuropeptide research duo: PT-141 (FDA-approved melanocortin agonist) + Oxytocin (bonding & reproductive hormone). Save 10% vs. individual prices.<\/p>","protected":false},"featured_media":867,"comment_status":"open","ping_status":"closed","template":"","meta":{"inline_featured_image":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0},"product_brand":[],"product_cat":[58],"product_tag":[245,247,250,255,246,251],"class_list":["post-886","product","type-product","status-publish","has-post-thumbnail","product_cat-hormones-reproductive-health","product_tag-libido","product_tag-melanocortin","product_tag-oxytocin","product_tag-research-grade","product_tag-sexual-function","product_tag-social-bonding","first","instock","shipping-taxable","product-type-grouped"],"_links":{"self":[{"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/product\/886","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/comments?post=886"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/media\/867"}],"wp:attachment":[{"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/media?parent=886"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/product_brand?post=886"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/product_cat?post=886"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/decodepeptides.com\/nl_nl\/wp-json\/wp\/v2\/product_tag?post=886"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}