In vitro effects of nonylphenol on motility, mitochondrial, acrosomal and chromatin integrity of ram and boar spermatozoa.

The objective of this study was to determine the effects of nonylphenol (NP) on viability of ram and boar sperm in vitro. Ram or boar spermatozoa were exposed to 1, 10, 100, 250 and 500 µg NP ml(-1) for 1, 2, 3 or 4 h. Computer-assisted sperm motility analysis (CASA) system was used to evaluate sperm motility characteristics. Flow cytometry was used to determine mitochondrial membrane potential (MMP) and chromatin integrity, while epifluorescent microscopy was used to determine sperm acrosomal status. Exposure of both species spermatozoa to 250 and 500 µg NP ml(-1) was detrimental to progressive motility (P < 0.05), and its adverse effect was significant at lower (100 µg NP ml(-1) ) concentration (P < 0.05). The percentages of ram and boar spermatozoa with high MMP declined drastically after exposures to ≥250 µg ml(-1) NP (P < 0.05). Unlike chromatin integrity, which did not appear to be altered by NP exposure, there were dose-dependent NP effects (P < 0.05) on acrosomal integrity of both species at as low as 1 µg ml(-1) NP for boar spermatozoa and 10 µg ml(-1) NP for ram spermatozoa. These data show adverse effects of NP on ram and boar spermatozoa and thus its potential harmful effects on male reproduction as NP is found in fruits, vegetables, human milk, fish and livestock products.

Activity/inactivity circadian rhythm shows high similarities between young obesity-induced rats and old rats.

The objective of the present study was to compare differences between elderly rats and young obesity-induced rats in their activity/inactivity circadian rhythm. The investigation was motivated by the differences reported previously for the circadian rhythms of both obese and elderly humans (and other animals), and those of healthy, young or mature individuals. Three groups of rats were formed: a young control group which was fed a standard chow for rodents; a young obesity-induced group which was fed a high-fat diet for four months; and an elderly control group with rats aged 2.5 years that was fed a standard chow for rodents. Activity/inactivity data were registered through actimetry using infrared actimeter systems in each cage to detect activity. Data were logged on a computer and chronobiological analysis were performed. The results showed diurnal activity (sleep time), nocturnal activity (awake time), amplitude, acrophase, and interdaily stability to be similar between the young obesity-induced group and the elderly control group, but different in the young control group. We have concluded that obesity leads to a chronodisruption status in the body similar to the circadian rhythm degradation observed in the elderly.

Heparin-induced capacitation but not intracellular alkalinization of bovine sperm is inhibited by Rp-adenosine-3',5'-cyclic monophosphorothioate.

The objective of this study was to investigate the importance of cAMP during capacitation of bovine sperm. The competitive antagonist of cAMP, Rp-adenosine-3'5'-cyclic monophosphorothioate (Rp-cAMP), blocked heparin-induced capacitation (p < 0.05). The effect of Rp-cAMP on heparin-induced capacitation was reversed by 8-bromo-cAMP. The maximal inhibitory effect on capacitation occuroff when Rp-cAMP was added at the start of sperm incubation. These results support an important role for cAMP-dependent protein kinases during heparin-induced capacitation of bovine sperm. Further support for a role for protein phosphorylation during capacitation came from the use of the protein phosphatase inhibitor, okadaic acid. Okadaic acid had no affect on heparin-induced capacitation of bovine sperm (p > 0.05); however, bovine sperm were capacitated by okadaic acid in the absence of heparin (p < 0.05). The relationship of cAMP to capacitation-associated changes in sperm intracellular pH (pHi) was investigated using image analysis of bovine sperm. The pHi of sperm increased during capacitation, and Rp-cAMP did not affect the change in pHi. We conclude that heparin-induced capacitation of bovine sperm involves an increase in cAMP and a protein phosphorylation event but that these do not induce the increase in pHi associated with capacitation.

Differences in the role of cyclic adenosine 3',5'-monophosphate during capacitation of bovine sperm by heparin or oviduct fluid.

Capacitation is an important maturational event in the life of a spermatozoan that allows the sperm to undergo a stimulus-induced acrosome reaction. Bovine sperm can be induced to undergo capacitation in vitro by heparin or oviduct fluid, and capacitation can be inhibited by glucose. We found that glucose did not interfere with 3H-heparin binding to sperm. Glucose inhibition of capacitation could be reversed in a dose-dependent manner by 8-bromo-cAMP or by the phosphodiesterase inhibitors isobutylmethylxanthine or caffeine, with ED50S of 25, 32, and 183 microM, respectively. The maximal effect of 8-bromo-cAMP on capacitation was during the first 2 h of a 4-h incubation. Sperm cAMP increased during capacitation with heparin from an initial value of 4.1 +/- 0.1 to 7.3 +/- 1.1 pmol cAMP/20 x 10(6) sperm at 4 h of incubation. Control sperm cAMP at 4 h increased only to 4.9 +/- 0.8 pmol cAMP/20 x 10(6) sperm. There were both similarities and differences in the characteristics of capacitation by heparin or oviduct fluid. Both glucose and protamine sulfate were found to suppress the heparin-dependent cAMP increase and inhibit capacitation. Capacitation by oviduct fluid was inhibited by either glucose or protamine sulfate. A small increase in sperm cAMP was associated with capacitation by oviduct fluid but was not affected by glucose or protamine sulfate.