Pituitary and melanophore responses to background in poecilia latipinna (Teleostei): Role of the pars intermedia PAS cell

J. N. Ball, T. F C Batten

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

Fish were adapted to black (B) or white (W) backgrounds for 28 days, or moved between B and W for shorter periods. Compared to W, B induced a darker dorsal surface, the recruitment of new ventral melanophores, and the dispersion of melanin in denervated caudal fin melanophores. These responses were identical in fish adapted to seawater (SW), one-third seawater ( 1 3 SW), or fresh water (FW). The effects of B were abolished (melanophore recruitment, melanin dispersion) or attenuated (dorsal darkening) by hypophysectomy. B did not affect pituitary MSH content or plasma cortisol levels. Examination of the pituitary showed that while the prolactin cells were activated by reduced salinity, only the pars intermedia PAS-positive cell (PIPAS cell) was activated by B, the PI melanotrope (PIPbH cell) and all the pars distalis cells being similar in structure on B and W. Neither the PIPAS nor the PIPbH cell was affected by the different salinities. The neurohypophysis showed no response to background. It is concluded that the melanophore responses to B are mediated by an unknown hormone secreted by the PIPAS cell, and reasons are adduced for believing that prolactin, ACTH, and MSH are not involved in these responses.
Original languageEnglish
Pages (from-to)233-248
Number of pages16
JournalGeneral and Comparative Endocrinology
Volume44
Issue number2
DOIs
Publication statusPublished - Jun 1981
Externally publishedYes

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