Apposition of enkephalinergic axons with cGnRH I-containing perikarya in turkey hen brain.
Several lines of evidence support a role of endogenous opioids in the brain's regulation of gonadotropin secretion in birds and mammals, although the neuroanatomic basis of such regulation is not clear. We used double-label fluorescence immunohistochemistry employing polyclonal antisera raised in sheep against chicken gonadotropin-release hormone I (cGnRH I) and in rabbits against met-enkephalin to determine whether the potential exists for synaptic contact between neurons containing these neuropeptides in the preoptic/septal region of domestic turkey breeder hens. The cGnRH I antiserum was highly specific for cGnRH I, while the met-enkephalin antiserum showed some cross-reactivity with leu-enkephalin. We found numerous instances in which enkephalinergic neuronal elements appeared to contact cGnRH I perikarya and axons in and around the diagonal band of Broca, the bed nucleus of the pallial commissure and in the lateral septal nucleus. These appositions, confirmed by confocal scanning microscopy, appear to provide a neuroanatomic basis for how enkephalinergic innervation might influence gonadotropin secretion in turkey hens by directly regulating activity of cGnRH I neurons.
Millam
J R
JR
Department of Animal Science, University of California, One Shields Avenue, Davis, CA 95616-8532, USA. jrmillam@ucdavis.edu
Wang
R
R
Craig-Veit
C B
CB
Siopes
T D
TD
D000818:Animals; D001369:Axons / Q000378:metabolism*; D001923:Brain Chemistry / Q000502:physiology*; D004396:Coloring Agents; D004745:Enkephalins / Q000378:metabolism*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D016707:Tissue Fixation; D014422:Turkeys / Q000378:metabolism*
D004396:Coloring Agents; D004745:Enkephalins; D007987:Gonadotropin-Releasing Hormone