We investigated the photoperiodic response of serotonin- and galanin (GA)-immunoreactive (ir) cells in the paraventricular organ (PVO) and infundibular nucleus (IF) of the Japanese quail and the interaction of these cells with gonadotropin-releasing hormone (GnRH)-ir neurons in the hypothalamus. Serotonin-ir cells were located in series from the PVO to the IF, and were connected with each other. The number of serotonin-ir cells differed significantly between light and dark phases on the short days (SD), but did not differ between light and dark phases on long days (LD). GA-ir cells were also found in the PVO and IF. The number of GA-ir cells under SD conditions was significantly greater than under LD conditions but did not change diurnally. Both serotonin-ir and GA-ir fibers ran along the GnRH-ir cells in the nucleus commissurae pallii. Serotonin-ir and GA-ir fibers were connected with the GnRH-ir fibers in the external layer of the median eminence (ME). We confirmed that GA-ir fibers were closely associated with serotoninir neurons in the PVO and IF. GA-ir neurons have at least 2 routes of regulating GnRH neurons directly, and indirectly via the serotonin-ir cells in the PVO and IF.
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1 May 2004
Photoperiodic Response of Serotonin- and Galanin-Immunoreactive Neurons of the Paraventricular Organ and Infundibular Nucleus in Japanese Quail, Coturnix coturnix japonica
Yuka Haida,
Takayoshi Ubuka,
Kazuyoshi Ukena,
Kazuyoshi Tsutsui,
Tadashi Oishi,
Satoshi Tamotsu
cerebrospinal fluid-contacting neurons
deep brain photoreceptor
immunohistochemistry
paraventricular organ
photoperiodic-gonadal response