Distribution of SST immunoreactive neurons and fibers in hypothalamus
The results of immunohistochemical staining in the hypothalamus of chick showed that SST immunoreactive neurons were distributed in the paraventricular nucleus (PVN), ventromedial nucleus (VMN), dorsal supraoptic decussation (DSD) and infundibular nucleus (IN). The shape of SST immunoreactive neurons were fusiform, round or oval. The cytoplasm was dark brown, the nucleus was obvious, and some neurons streched out long processes. Meanwhile, SST immunoreactive fibers were distributed in the median eminence (ME), as well as in PVN, VMN, DSD and IN (Fig. 1).
Effects of monochromatic lights and different treatments on the levels of SST mRNA in hypothalamus and pituitary
There was no interaction between monochromatic lights and different treatment groups on the levels of SST mRNA in hypothalamus (F6,52 = 0.505, P = 0.801) and pituitary (F6,48 = 0.491, P = 0.812). The results showed that monochromatic lights and treatment groups significantly affected SST mRNA levels in hypothalamus (monochromatic lights: F3,52 = 3.459, P = 0.023; treatments:F2,52 = 17.705, P = 0.000) and pituitary (monochromatic lights: F3,48 = 5.456, P = 0.003; treatments: F2,48 = 56.509, P = 0.000). The main effect analysis showed that SST mRNA in hypothalamus and pituitary in RL were higher than those of in GL by 25.40% (P = 0.025) and 13.60% (P = 0.001). However, no difference was observed between other monochromatic lights. Meanwhile, SST mRNA in hypothalamus and pituitary in pinealectomy group were higher by 37.45%-39.88% (hypothalamus, P = 0.000) and 26.46%-27.23% (pituitary, P = 0.000) than those of in intact and sham operation groups, respectively (Fig. 2A and 2B).
Effects of monochromatic lights and different treatments on the levels of SST protein in hypothalamus and pituitary
There was no interaction between monochromatic lights and different treatment groups on the levels of SST protein in hypothalamus (F6,45 = 0.727, P = 0.630). The results showed that the levels of SST protein in hypothalamus were significantly affected by monochromatic lights (F3, 45 = 9.516, P = 0.000) and treatment groups (F2, 45 = 15.859, P = 0.000). The main effect analysis showed that hypothalamic SST protein in RL were higher than those of in GL by 16.37% (P = 0.000) and in BL by 14.17% (P = 0.001), respectively. However, there was no significant difference between GL and BL (P > 0.05). Meanwhile, SST protein in the pinealectomy group was higher by 12.54% (P = 0.000) and 15.58% (P = 0.000) than that of in intact and sham operation groups, respectively (Fig. 2C).
There was interaction between monochromatic lights and different treatment groups on the levels of SST protein in pituitary (F6,45 = 8.021, P = 0.000). The interaction analysis showed that the SST protein levels in the intact and the sham operation groups in GL and BL was lower by 20.43%-23.22% and 16.37%-19.28% than that of in RL (P = 0.000), respectively. However, the SST protein levels in the pinealectomy group in BL was higher by 1.38% than that of in WL (P > 0.05). The difference was 16.80% (P = 0.000) (Fig. 2D).
Effects of monochromatic lights and different treatments on the levels of SSTR2 and SSTR5 mRNA in hypothalamus and pituitary
There was no interaction between monochromatic lights and different treatment groups on the levels of SSTR2 mRNA in hypothalamus (F6,54 = 0.879, P = 0.516) and pituitary (F6,48 = 1.699, P = 0.142). The levels of SSTR2 mRNA in hypothalamus and pituitary were significantly influenced by monochromatic lights (hypothalamus: F3,54 = 7.515, P = 0.000; pituitary: F3,48 = 6.425, P = 0.001) and treatment groups (hypothalamus: F2,54 = 31.272, P = 0.000; pituitary: F2,48 = 62.088, P = 0.000).The main effect analysis showed that SSTR2 mRNA in RL was higher than that of in GL and BL by 19.46% (P = 0.001) and 17.01% (P = 0.002) in hypothalamus, and by 15.37% (P = 0.002) and 14.59% (P = 0.005) in pituitary, respectively. Meanwhile, SSTR2 mRNA in pinealectomy group was higher than intact and sham operation groups by 28.15% (P = 0.000) and 26.86% (P = 0.000) in hypothalamus, and by 37.38% (P = 0.000) and 31.07% (P = 0.000) in pituitary, respectively (Fig. 3A and 3B).
There was no interaction between monochromatic lights and different treatment groups on the levels of SSTR5 mRNA in the hypothalamus (F6,45 = 0.121, P = 0.993) and pituitary (F6,45 = 2.010, P = 0.084). The statistical analysis showed that the treatment groups significantly affected the levels of SST5 mRNA in hypothalamus (F2,45 = 3.517, P = 0.038) and pituitary (F2,45 = 56.708, P = 0.000). The main effect analysis showed that SSTR5 mRNA in pinealectomy group in hypothalamus was lower by 21.91% than that of in intact group (P = 0.043). However, the unweighted marginal mean value of SSTR5 mRNA in pinealectomy groupin pituitary was higher by 47.83% than that of in intact group (P = 0.000) (Fig. 3C and 3D).
Effects of monochromatic lights and different treatment groups on the levels of SSTR2 protein in hypothalamus and pituitary
There was no interaction between monochromatic lights and different treatment groups on the levels of SSTR2 protein in hypothalamus (F6,43 = 1.868, P = 0.108) and pituitary (F6,45 = 1.775, P = 0.126). However, the levels of SSTR2 protein in hypothalamus and pituitary were influenced by monochromatic lights (hypothalamus: F3,43 = 12.667, P = 0.000; pituitary: F3,45 = 10.250, P = 0.000) and treatment groups (hypothalamus: F2,43 = 85.650, P = 0.000; pituitary: F2,45 = 102.038, P = 0.000). The main effect analysis results showed that SSTR2 protein in hypothalamus and pituitary in RL were higher than those of in the other light groups by 11.63%-21.74% (P = 0.000-0.013) and 5.16%-9.62% (P = 0.000-0.038), respectively. Meanwhile, SSTR2 protein of hypothalamus and pituitary in pinealectomy group were higher by 36.73%-42.64% (P = 0.000) and 20.13%-20.34% (P = 0.000) than those of other treatment groups, respectively (Fig. 3E and 3F).