Gonadotropin-inhibitory hormone (GnIH), a neuropeptide that inhibits gonadotropin synthesis and
release, was first identified in the quail hypothalamus. To understand the physiological role of GnIH, this
review will demonstrate the mechanisms that regulate GnIH synthesis and release. Pinealectomy (Px)
combined with orbital enucleation (Ex) decreased the synthesis of GnIH precursor mRNA and content
of mature GnIH peptide in the diencephalon. Melatonin administration to Px plus Ex birds caused a
dose-dependent increase in the synthesis of GnIH precursor mRNA and production of mature peptide.
A melatonin receptor subtype, Mel1c, was expressed in GnIH-immunoreactive neurons, suggesting direct
action of melatonin on GnIH neurons. Melatonin administration further increased GnIH release in a dosedependent
manner from hypothalamic explants in vitro. GnIH mRNA expression and GnIH release during
the dark period were greater than those during the light period in explants from quail exposed to longday
photoperiods. Conversely, plasma luteinizing hormone (LH) concentration decreased during the dark
period. This review summarizes that melatonin appears to act on GnIH neurons in stimulating not only
GnIH synthesis but also its release, thus inhibiting plasma LH concentration in birds. and agricultural lands
(tea, coffee); and the potential origins of many sacred groves as forest fragments and their future roles as
cultural, social and ecological centers of reforestation within deforested landscapes. Studies that focus on
restoration have demonstrated the benefits of plantations as mechanisms to establish second growth forests
and native species plantings for both economic and conservation purposes; the incorporation of
indigenous plants that produce non-timber forest products in forest restoration programs; and the control
of fire, soil preparation and protection from herbivory as treatments that can facilitate natural forest
regeneration in montane grasslands.