Substance P-like-immunoreactive neurons in the photosensory pineal organ of the rainbow trout, Salmo gairdneri Richardson (Teleostei)

Research output: Contribution to journalArticle


Restricted numbers of substance P-like-immuno-reactive (SPL-IR) neurons were demonstrated in the photosensory pineal organ of the rainbow trout. The small parapineal organ of this teleost species receives a distinct SPL-IR innervation via the habenular nuclei, but displays no intrinsic SPL-IR neurons. Intrapineal SPL-IR neurons were located in the rostral portion of the pineal end-vesicle. Neuronal somata were found in a lateral position with smooth axonal processes extending mediad. Immunoreactive somata and axonal processes were observed intraparenchymally as well as in the pineal lumen. The pattern of immunoreactivity was not changed in excised pineal organs that had been incubated in tissue culture medium in the dark for 18 h. The possibility that the intrapineal SPL-IR neurons are not part of the neural circuitry involved in the transduction of photic information, but may have other functions, is discussed.


External organisations
  • Justus Liebig University Giessen
Research areas and keywords


  • Immunohistochemistry, Neuronal types, Pineal organ, Salmo gairdneri (Teleostei), Substance P
Original languageEnglish
Pages (from-to)359-364
Number of pages6
JournalCell and Tissue Research
Issue number2
Publication statusPublished - 1986 Nov 1
Publication categoryResearch