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Melatonin profiles in the cerebrospinal fluid (CSF) of conscious goats were examined under long-day (16L:8D) and short-day (8L:16D) environments. CSF melatonin, collected from the lateral ventricle, showed distinct 24 h rhythms with high concentrations being restricted to the dark phase, which averaged 1,320.6 pg/ml under 16L:8D and 660.6 pg/ml under 8L:16D. On the contrary, the nocturnal rise in CSF melatonin was totally absent in the pineal sympathetically denervated animals. Night interruption by 1 h lighting (about 400 lux at the height of goat's head) resulted in an abrupt decline of CSF melatonin to the basal level within 30 min and immediate recovery to the previous high level after reestablishment of the dark phase. The CSF/plasma ratio was 10.8-18.4 during the dark phase and 1.7-1.8 during the light phase. CSF and plasma melatonin levels were also examined after exogenous melatonin given either peripherally or intraventricularly. Continuous subcutaneous infusion of melatonin (5 micrograms/h) maintained melatonin levels in the plasma about 3 times higher than that in the CSF during its application. On the other hand, an intraventricular injection of 2 micrograms melatonin elevated plasma melatonin by 100 pg/ml within 1 min. These results indicate that turnover of CSF melatonin is fairly rapid and favor a hypothesis for direct access of pineal melatonin to the brain ventricular system in the goat.

Melatonin in the extracellular space of the pineal gland was measured continuously for 4 consecutive days from single, freely moving rats by means of in vivo microdialysis. A robust circadian rhythm was observed in the pineal extracellular melatonin under both light-dark (LD) and continuous dark (DD) conditions, the patterns of which were almost identical for 4 days within individuals but varied substantially among individuals. The offset phase of melatonin rhythm was more stable than the onset phase. Light-induced phase shift of melatonin rhythm was measured in individual rats, which had been entrained to LD and subsequently released into DD. On the 1st day in DD, a 3-min light pulse of 200 lx was applied either at circadian time (CT) of 17 or 22 h (5 and 10 h after the dark onset, respectively). The light pulse rapidly suppressed the nocturnal melatonin level. The rate as well as the level of melatonin suppression was significantly greater by the pulse at CT22 than at CT17. A phase shift of the melatonin rhythm was calculated on the 2nd and 3rd days in DD. Significant phase delay shift was observed after the pulse at CT17 and advance shift after the pulse at CT22 of approximately 1 h in either case. Because the amount of phase shift was not different between the 2nd and 3rd days in DD, the phase shift of pineal melatonin rhythm by single light pulse seems to be completed immediately.

Abstract. Meishan pigs are known for their early sexual maturity. On the other hand, they grow slowly. There is no information currently available about the combination of these two characteristics in Meishan pigs. To study the developmental characteristics of Meishan pigs, the plasma concentrations of LH, FSH, inhibin, testosterone, estradiol-17β, progesterone and insulin-like growth factor-I (IGF-I) in young Meishan boars were determined using RIA and ELISA. Inhibin decreased with age in weeks, while testosterone and estradiol-17β increased. Testosterone increased gradually, and an increase in estradiol-17β occurred after sexual maturity. IGF-I increased before puberty and subsequently decreased just after puberty like a pubertal IGF-1 surge. FSH, LH and progesterone did not change with age. There was no significant correlation among the hormones. During the experimental period, the Meishan boars showed large individual differences. These differences may depend on the fact that Meishan boar reach maturity at 12 weeks of age and continue to grow thereafter.

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Aims: There is increasing concern about the effect of environmental toxins and endocrine disrupters on human spermatogenesis but ethical considerations prohibit direct research. Therefore, we developed a method of isolating mature pig Sertoli cells and studying the levels of mRNA of transferrin and inhibin, markers of Sertoli cell function, using real-time polymerase chain reaction analysis.Methods: Sertoli cells from mature Meishan boars were isolated and cultured. The mRNA was isolated from the cells after 3 days of treatment with follicle-stimulating hormone (FSH), testosterone and β-estradiol. The amounts of transferrin and inhibin mRNA were analyzed by real-time polymerase chain reaction and the relative level of mRNA was calculated.Results: FSH tended to increase the levels of transferrin and inhibin mRNA, as did the combinations of FSH and the steroids. The effect of testosterone and β-estradiol alone on the level of mRNA was less than that of FSH. Beta-estradiol treatment resulted in a dose-dependent decrease in mRNA. Conclusion:The Sertoli cell culture used in the present study appears to have a normal secretory function because the mRNA levels of both markers increased after FSH treatment. The suppressive effect of β-estradiol on inhibin mRNA level suggests that β-estradiol has an effect on the function of Sertoli cells. (Reprod Med Biol 2005; 4: 259-264)

In order to study the possibility of using lymphocyte subsets as a stress indicator, the changes of the subset proportion in peripheral blood were examined after transportation. Six 3-month-old male Holstein calves were transported for about 3 h in a lorry via an ordinary road. Blood samples were collected at the expected unloading time on the day before transport (T0), immediately after unloading (T1), 24 h after unloading (T2), and 1 week after unloading (T3). CD2, CD4, CD8, CD21, CD25, WC1, and NKp46 antigens on peripheral blood mononuclear cells were measured by flow cytometry. There was an increase in the proportions of CD25+ cells and WC1+ γδT cells at T1 and T2. The proportions of NK cells increased at T1, including an increase in the population of CD2-NK cells. CD2+ NK cells did not show any change. The proportions at T1 were lower than at T3 in CD21+ B cells. CD4+ and CD8+ αβT cells did not change significantly, although CD2+ T cells showed a trend toward reduction at T1. Consequently, CD2-NK cells and WC1+ γδT cells might offer potential as stress index for calf transport.