With no detectable effect on GnRH release from the hypothalamus. On the same rats, upon i.p. injection of the same peptide at high doses, serum LH showed a moderate increase, while after central administration of TLQP-21 in adults animals, the LH response was dependent on the stage of the reproductive cycle. On the whole, TLQP-21 would so far appear to affect female reproduction by stimulating pituitary LH release. We produced antisera selective for the C-and N-terminal portions of the VGF precursor, and for two cleaved peptides “TLQP” and “PGH”, to be used for immunohistochemistry and enzyme-linked immunosorbent assay, complemented with gel chromatography. We addressed the localisation and changes of VGF peptides in the female rat reproductive axis in connection with the estrous cycle, as well as after ovariectomy. Their presence and modulation in plasma was outlined in parallel, as a clue to their possible endocrine significance. In addition, in view of its selective distribution in the hypothalamus, the Afatinib ability of the TLQP-21 peptide to release somatostatin or growth-hormonereleasing hormone was tested in vitro. Our study demonstrated the presence of several peptides derived from the VGF precursor, with selective differential profiles at all levels of the hypothalamic-pituitary-ovarian axis. A striking modulation in peptide tissue levels including plasma was shown across the estrous cycle, implicating VGF peptides in events and mechanisms relevant to reproduction. In view of the proposed role of VGF as multifunctional precursor of bioactive peptides our study was focused on end products of the VGF precursor, rather than on the primary VGF gene product itself. The primary sequence of VGF shows at least ten putative cleavage sites, in the form of two or more basic amino acid residues, highly conserved across species. Recently, further fragments including bioactive VGF peptides have been shown to derive from cleavage at single basic amino acids. In view of the lower proteomic complexity of the cerebro-spinal fluid, the precise chemical nature of VGF derived end products has so far been mostly studied in such body fluid with the addition of neuro-endocrine cells lines. An array of VGF peptides and fragments have been revealed, with striking changes in neurodegenerative and other disease conditions. Certain VGF peptides proved to be released in vivo in the brain upon neuronal depolarization while an interactomic investigation revealed selective domains of VGF, including the TLQP-21 region, as likely binding partners for the amyloid precursor protein. Similarly, two peptides derived from non-overlapping regions of the VGF precursor were reported in the protein-bound and unbound fractions, respectively, from CSF. In the present study, TLQP-antibodies showed several chromatography peaks fitting well with known VGF peptides, such as TLQP-21, 30 and 62. Products derived from the C-terminal domain of VGF have been studied in some detail and the major molecular form/s we found in hypothalamus and pituitary may represent socalled VGF18 and 20. In connection with the TLQP-62 peak shown here with the relevant N-terminal antibody, a lower amount of reactivity was revealed in chromatography with the corresponding C-terminus antibody.