The Mystery Actor in the Neuroendocrine Theater: Who Really Knows Obestatin? Central Focus on Hypothalamic–Pituitary Axes

The available literature data indicate that obestatin, a peptide derived from the preproghrelin precursor, may modulate neuroendocrine function, particularly in appetite regulation and somatotrophic/gonadotrophic pathways. This review synthesizes animal studies assessing the influence of obestatin on central neuroendocrine systems. Obestatin has been shown to affect the hypothalamic appetite-regulating center through neuropeptides such as neuropeptide Y and agouti-related peptide, yet findings remain inconsistent between species. In rodents, its effects on food intake and energy balance are inconclusive, whereas sheep models demonstrate significant alterations in orexigenic gene expression and peptide immunoreactivity. Regarding the somatotrophic axis, obestatin showed no significant effect on growth hormone (GH) secretion in rodents; however, in sheep, it modulated growth hormone-releasing hormone and somatostatin mRNA expression, elevated pituitary GH synthesis, and increased circulating GH levels. Studies involving the gonadotrophic axis demonstrated the presence of obestatin in Leydig and pituitary cells, with in vitro evidence suggesting its ability to modulate intracellular pathways implicated in gonadoliberin, luteinizing hormone, and follicle-stimulating hormone release. The collective findings discussed in this article indicate that obestatin interacts with multiple hypothalamic–pituitary axes, though its effects vary depending on species and experimental conditions. This review highlights the complexity of obestatin’s central actions and the need for further research to elucidate its functional relevance in neuroendocrine regulation.