Stable Network Homeostasis during Multi-Level Postnatal Maturation of the Mouse Tuberoinfundibular Dopamine–Prolactin Axis

The hypothalamus orchestrates endocrine function via specialized neuronal populations that interface with the pituitary gland. While postnatal circuit refinement is a hallmark of most neural systems, its contribution to hypothalamic neuroendocrine networks remains elusive. Among these populations, tuberoin-fundibular dopamine (TIDA) neurons of the arcuate nucleus are the primary source of tonic inhibition of prolactin (Prl), a hormone essential for reproduction, parental physiology, and behavior. While Prl levels surge during early mouse postnatal life, it remains unclear whether the TIDA system is fully developed at birth or undergoes functional maturation. Here, we combined immunofluorescence, slice electrophysiology, and Ca2+ imaging to determine the development of TIDA neurons in mice during the first three postnatal weeks. Expression of dopaminergic markers was sparse at birth but rose substantially after the first week, followed by the onset of median eminence innervation by TID

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