We recently found lumbosacral sympathetic ganglionic galanin neurons innervating the quail uterine oviduct. Galaninergic innervation of the uterine muscle may be essential for avian oviposition, as galanin evoked oviposition through a mechanism of induction of vigorous uterine contraction. The questions arising from these findings are: what changes occur in galanin expression in the sympathetic ganglionic galanin neuron during development, and what is the hormonal factor(s) that induces galanin expression in this neuron? Therefore, the present study examined the developmental changes in galanin of the quail sympathetic ganglionic neuron and uterus, and the effect of administration of ovarian sex steroids on galanin induction. Immature birds reared under long-day photoperiods from 4 weeks of age demonstrated progressive increases in galanin levels both per unit ganglionic protein (concentration) and per ganglia (content) concurrent with ganglionic development during weeks 4--13. The uterine galanin content and uterine weight also increased progressively during the same period, but the galanin concentration in the uterus at 4 weeks was high due to the much smaller tissue mass. Immunocytochemical analysis with anti-galanin serum showed that immunoreactive ganglionic cells were few and small at 4 weeks and increased progressively thereafter. Administration of oestradiol-17 beta to immature birds at 3 weeks of age for 1 week increased both the galanin concentration and content in the ganglia without ganglionic growth. A marked increase in galanin-immunoreactive ganglionic cells was detected following oestradiol treatment. In contrast, progesterone increased ganglionic galanin levels, but the effects were low. Expression of the mRNAs encoding oestrogen receptor-alpha and -beta (ER alpha and ER beta) in the ganglionic tissue was verified by RT-PCR/Southern blot analysis. Immunocytochemical staining with anti-ER serum further revealed an intense immunoreaction restricted to the nucleus of ganglionic neurons. These results suggest that ovarian sex steroids, in particular oestradiol-17 beta, contribute as hormonal factors to galanin induction, which takes place in the lumbosacral sympathetic ganglionic neurons innervating avian uterine oviduct during development. Oestradiol may act directly on this ganglionic neuron through intra-nuclear receptor-mediated mechanisms to induce galanin.

ABSTRACT

Advances in techniques in molecular biology have facilitated the research into endogenous opioids and related peptides in several ways. The organization and expression of genes and the primary structure of three precursor proteins of opioid peptides have been elucidated. These studies predicted the presence of potentially bioactive peptides, which has been confirmed by later studies. Advances in techniques in protein chemistry have helped to elucidate the distribution and molecular forms of endogenous opioids and related peptides in the body, and the processing of precursor proteins. Studies on the function of these peptides have shown a broad spectrum of actions. Leumorphin, a newly identified peptide, has been shown to exhibit unique biological activities. In spite of extensive studies, the physiological and pathophysiological significance of opioid peptide systems are not yet completely understood. This is mainly due to the paucity of our knowledge about opioid receptors. Further studies on the subtypes of opioid receptors will help to elucidate all aspects of the function of endogenous opioids and related peptides.

J. Endocr. (1985) 107, 147–157