Localization of avian LHRH-immunoreactive neurons in the hypothalamus of the domestic fowl, Gallus domesticus, and the Japanese quail, Coturnix coturnix

Summary

The localization of LHRH-containing perikarya and nerve fibers in the hypothalami of the domestic fowl and Japanese quail was investigated by means of the specific immunoperoxidase ABC method, using antisera against chicken LHRH-I ([Gln⁸]-LHRH), chicken GnRH-II ([His⁵-Trp⁷-Tyr⁸]-LHRH [2–10]) and mammalian LHRH ([Arg⁸]-LHRH). Chicken LHRH-I-immunoreactive perikarya were sparsely scattered in the nucleus preopticus periventricularis (POP), nucleus filiformis (FIL) and nucleus septalis medialis (SM), and in bilateral bands extending from these nuclei into the septal area in both species. A few reactive perikarya were also observed in the nucleus accumbens (Ac) and lobus parolfactorius (LPO). Numerous cLHRH-I-immunoreactive fibers were widely scattered in the preoptic, septal and tuberal areas, and were densely concentrated in the external layer of the median eminence and in organum vasculosum of the lamina terminalis (OVLT) in both species. Anti-mammalian LHRH serum cross-reacted weakly with perikarya and fibers immunoreactive to anti-cLHRH-I serum in normal chicken and quail. Anti-cGnRH-II[2–10] serum immunoreacted with magnocellular neurons distributed in the rostral end of the mesencephalon along the midline close to the nervus oculomotorius (N III). These perikarya were apparently different from cLHRH-I immunoreactive neurons. No immunoreactive cells and fibers against anti-cGnRH-II[2–10] were observed in the hypothalamus and median eminence of the chicken or quail. Anti-cGnRH-II[2–10] bound specifically with cGnRH-II. The morphological evidence suggests that cGnRH-II may not be secreted into the portal circulation to act as hypothalamic hormone.