TIP39, a neuropeptide and an agonist for the parathyroid hormone receptor type 2 (PTH2R), effectively increases cAMP levels in COS-7 cells featuring recombinant PTH2R from humans or rats (EC50s = 0.5 and 0.8 nM, respectively), as well as in F-11 cells that naturally express PTH2R (EC50 = 1.15 nM). Furthermore, TIP39 at 1 nM halts the cell cycle at the G0/G1 phase and reduces Sox9 expression, a crucial regulator of cartilage differentiation, in CFK2 rat chondrocytes. Additionally, administering 100 pmol/animal of TIP39 reduces the immobility period in the forced swim test in mice, indicating a potential antidepressant effect.

Tianeptine metabolite MC5, an active derivative of the atypical antidepressant tianeptine produced through β-oxidation, exhibits selective G protein activation in bioluminescence resonance energy transfer (BRET) assays. Utilizing HEK293T cells expressing the human μ-opioid receptor (MOR) over the human δ-opioid receptor (DOR; EC50s = 0.454 and >100 µM, respectively), it demonstrates specificity. Moreover, this metabolite reduces immobility in wild-type mice during the forced swim test at a dose of 30 mg/kg, an effect not observed in MOR knockout mice, suggesting its antidepressant-like activity is MOR-dependent.

Urocortin III is a neuropeptide hormone and member of the corticotropin-releasing factor (CRF) family which includes mammalian CRF , urocortin , urocortin II , frog sauvagine, and piscine urotensin I.1 Human urocortin III shares 90, 40, 37, and 21% identity to mouse urocortin III , mouse urocortin II , human urocortin , and mouse urocortin, respectively. Urocortin III selectively binds to type 2 CRF receptors (Kis = 21.7, 13.5, and >100 nM for rat CRF2α, rat CRF2β, and human CRF1, respectively). It stimulates cAMP production in CHO cells expressing rat CRF2α and mouse CRF2β (EC50s = 0.16 and 0.12 nM, respectively) as well as cultured anterior pituitary cells expressing endogenous CRF2β. Urocortin III is co-released with insulin to potentiate glucose-stimulated somatostatin release in vitro in human pancreatic β-cells.2 In vivo, urocortin III reduces food intake in a dose- and time-dependent manner in mice with a minimum effective dose (MED) of 0.3 nmol/animal.3 It increases swimming time in a forced swim test in mice, indicating antidepressant-like activity.4References1. Lewis, K., Li, C., Perrin, M.H., et al. Identification of urocortin III, an additional member of the corticotropin-releasing factor (CRF) family with high affinity for the CRF2 receptor. Proc. Natl. Acad. Sci. U.S.A. 98(13), 7570-7575 (2001).2. van der Meulen, T., Donaldson, C.J., Cáceres, E., et al. Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion. Nat. Med. 21(7), 769-776 (2015).3. Pelleymounter, M.A., Joppa, M., Ling, N., et al. Behavioral and neuroendocrine effects of the selective CRF2 receptor agonists urocortin II and urocortin III. Peptides 25(4), 659-666 (2004).4. Tanaka, M., Kádár, K., Tóth, G., et al. Antidepressant-like effects of urocortin 3 fragments. Brain Res. Bull. 84(6), 414-418 (2011). Urocortin III is a neuropeptide hormone and member of the corticotropin-releasing factor (CRF) family which includes mammalian CRF , urocortin , urocortin II , frog sauvagine, and piscine urotensin I.1 Human urocortin III shares 90, 40, 37, and 21% identity to mouse urocortin III , mouse urocortin II , human urocortin , and mouse urocortin, respectively. Urocortin III selectively binds to type 2 CRF receptors (Kis = 21.7, 13.5, and >100 nM for rat CRF2α, rat CRF2β, and human CRF1, respectively). It stimulates cAMP production in CHO cells expressing rat CRF2α and mouse CRF2β (EC50s = 0.16 and 0.12 nM, respectively) as well as cultured anterior pituitary cells expressing endogenous CRF2β. Urocortin III is co-released with insulin to potentiate glucose-stimulated somatostatin release in vitro in human pancreatic β-cells.2 In vivo, urocortin III reduces food intake in a dose- and time-dependent manner in mice with a minimum effective dose (MED) of 0.3 nmol/animal.3 It increases swimming time in a forced swim test in mice, indicating antidepressant-like activity.4 References1. Lewis, K., Li, C., Perrin, M.H., et al. Identification of urocortin III, an additional member of the corticotropin-releasing factor (CRF) family with high affinity for the CRF2 receptor. Proc. Natl. Acad. Sci. U.S.A. 98(13), 7570-7575 (2001).2. van der Meulen, T., Donaldson, C.J., Cáceres, E., et al. Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion. Nat. Med. 21(7), 769-776 (2015).3. Pelleymounter, M.A., Joppa, M., Ling, N., et al. Behavioral and neuroendocrine effects of the selective CRF2 receptor agonists urocortin II and urocortin III. Peptides 25(4), 659-666 (2004).4. Tanaka, M., Kádár, K., Tóth, G., et al. Antidepressant-like effects of urocortin 3 fragments. Brain Res. Bull. 84(6), 414-418 (2011).

Galanin (2-11) amide is a synthetic peptide fragment of the neuropeptide galanin and an agonist of the galanin-2 (GAL2) receptor (EC50= 9.32 nM in a fluorescence imaging plate reader assay).1It selectively binds to the GAL2receptor (IC50= 1.76 nM for the rat receptor) over the GAL1receptor (IC50= 879 nM for the human receptor) but does also bind to the GAL3receptor (Ki= 271 nM for the rat receptor).1,2Intracerebroventricular administration of galanin (2-11) amide (1 nmol/animal) decreases immobility in the forced swim test in rats.3It also reduces the hind paw mechanical pain threshold and increases the hind paw cold sensitivity threshold in rats.1