Plasticity in Expression of Immunoreactivity for Neuropeptide Y, Enkephalins and Neurotensin in the Hypothalamic Tubero‐lnfundibular Dopaminergic System during Lactation in Mice

Publisher Website
Google Scholar
Abstract
In lactating nursing vs lactating pup‐deprived mice, single or multiple immunolabeling was performed to compare immunoreactivities (ir) for neuropeptide Y (NPY), enkephalins (ENK) and neurotensin (NT) in the tyrosine hydroxylase (TH)‐ir hypothalamic tubero‐infundibular dopaminergic (TIDA) system. NPY‐, ENK‐ and NT‐irs were intensely expressed and coexisted in virtually all TH‐ir endings in the median eminence (ME) of nursing mice. Removal of the pups induced a marked depletion of the peptide‐irs from the ME TH‐ir endings. In the arcuate nucleus (ARC) of colchicine‐treated nursing mice which received peripheral injections of Fluoro‐Gold (FG) to retrogradely label neuroendocrine cells, virtually all dorsal A12 TH‐ir perikarya simultaneously expressed, with individual variations, NPY‐, ENK‐ and NT‐irs, and all contained FG. These results suggest that the synthesis of NPY, ENK and NT is enhanced in TIDA neurons during lactation and that these neuromessengers may be co‐released together with DA from the ME to regulate the suckling‐induced prolactin secretion at the hypothalamic and/or pituitary levels.