Effect of Stress During Handling, Seawater Acclimation, Confinement, and Induced Spawning on Plasma Ion Levels and Somatolactin‐Expressing Cells in Mature Female Liza ramada

Abstract

The present experiments were designed to determine the effect of different stress factors; handling, seawater acclimation, confinement, and induced spawning on plasma cortisol, hydro mineral balance as well as changes in size, number and integrated intensity of somatolactin (SL)-expressing cells in Liza ramada mature females confined to fresh water ponds. The plasma levels of cortisol, PO(4)(3-), Na(+), and K(+) were higher, while Ca(2+) and Mg(2+) were lower than controls during transportation without anesthesia. By using clove oil (5 mg L(-1)) as an anesthetic during transportation, the plasma cortisol, PO(4) (3-), Na(+), and K(+) were similar to controls, while Ca(2+) and Mg(2+) were higher. During seawater acclimation, the plasma cortisol and minerals were significantly higher except Na(+) which was lower than controls. In addition, during induction of spawning, the plasma levels of cortisol, PO(4)(3-), Na(+), K(+), and Mg(2+) were significantly higher than controls. The SL-producing cells are located in the pars intermedia (PI) bordering the neurohypophysis. The stress affected the number, size, and immunostaining of SL-expressing cells. During seawater acclimation, the size and the integrated intensity of SL immunoreactivity were lower, but the number of these cells was higher than controls. Furthermore, the number, size, and the integrated intensity of SL immunoreactivity were significantly lower than controls during handling and after spawning, which was opposite to confinement. The response of SL-expressing cells in PI in parallel with changes in cortisol and hydro mineral balance induced by stress support the possible role of SL in the adaptive response of fish to stress.

Signal transduction mechanisms for autocrine/paracrine regulation of somatolactin-α secretion and synthesis in carp pituitary cells by somatolactin-α and -β

“…Similar to GH and PRL, SL is a member of the class I cytokines with the typical feature of four ␣-helixes arranged in an up-up-down-down topography (16). To date, SL has been associated with diverse functions in fish models, including reproduction (29,36), stress (21), lipid metabolism (40), background adaptation (53,55), phosphate transport (25), melanosome aggregation (28,54), and immune responses (4). Although most of the above-mentioned functions attributed to SL were based on correlational studies, the functional role of SL in color presentation has been unequivocally demonstrated in fish species.…”

Expression pattern of somatolactin in the Chinese sturgeon,Acipenser sinensisGray, 1835

“…Immunohistochemistry observation has shown that both forms of SL expressed in differing cell populations located in the PI of goldfish, but not in the RPD (rostral pars distalis), PPD, or caudal pars distalis (Azuma et al., ). Recently, some studies also reported the PI‐specific expression of SL such as in thin‐lipped gray mullet ( Liza ramada ) (Khalil et al., ), tabarana ( Salminus hilarii ) (Honji et al., ) and grass carp ( Ctenopharyngodon idella ) (Grandi et al., ). However, in addition to the PI location, isolated or clustered SL cells have also been found in the PPD in Mediterranean yellowtail (García‐Hernández et al., ) and white seabream (Segura‐Noguera et al., ).…”

Factors That Can Influence Animal Research

“…In mice, anxiety can be reduced by use of handling tunnels and other aids (Gouveia and Hurst, 2013). Stress induces physiologic changes in fishes similar to those seen in mammalian species (Khalil et al, 2012).…”