Sperm Metabolic Activity Research Articles

Does salinity variation increase synergistic effects of triclosan and carbon nanotubes on Mytilus galloprovincialis? Responses on adult tissues and sperms

The use of carbon nanotubes (CNTs) is rapidly increasing and several scientific studies have addressed their toxicological properties. However, only a very small number of publications have deal with the interaction between CNTs and other molecules. Triclosan (TCS) is an antibacterial agent used in personal care and household products. Commonly detected in aquatic ecosystems, there is a strong evidence that aquatic biota is sensitive to this compound. Aside from emergent pollutants, aquatic organisms are continuously subjected to abiotic variations including salinities. Therefore, the main goal of the present study was to better understand how physio-chemical interactions of CNTs with TCS under different salinity levels (37, 28 and 19) affect the mussel species Mytilus galloprovincialis through the evaluation of biochemical alterations on gametes (sperms) and adult tissues, providing more ecologically relevant information on organisms' responses. The results showed toxicological effects in terms of sperm metabolic activity and intracellular reactive oxygen species production as well as cellular damage and alteration of metabolic capacity at the adult's stage when exposed to both contaminants acting alone and in combination, under tested salinities. Moreover, when the mussels were exposed to the combination of both contaminants, they showed major toxic impacts on both assessed biological levels (adult tissues and sperms) especially under control salinity. This suggests that toxicity upon mixture exposure compared to single-substance exposure may impair mussels' populations, affecting reproduction success and growth.

Glutathione S-Transferases Play a Crucial Role in Mitochondrial Function, Plasma Membrane Stability and Oxidative Regulation of Mammalian Sperm.

Glutathione S-transferases (GSTs) are essential sperm antioxidant enzymes involved in cell protection against oxidative stress and toxic chemicals, preserving sperm function and fertilising ability. Artificial insemination (AI) in pigs is commonly carried out through the use of liquid-stored semen at 17 °C, which not only reduces sperm metabolic activity but also sperm quality and AI-farrowing rates within the 72 h of storage. While one may reasonably suggest that such enzymes are implicated in the physiology and maintenance of mammalian sperm function during liquid-storage, no previous studies conducted on any species have addressed this hypothesis. Therefore, the objective of the present work was to characterise the presence and function of sperm GSTs in mammalian sperm, using the pig as a model. In this regard, inhibition of such enzymes by ethacrynic acid (EA) during semen storage at 17 °C was performed to evaluate the effects of GSTs in liquid-preserved boar sperm by flow cytometry, immunofluorescence, and immunoblotting analysis. The results of this study have shown, for the first time in mammalian species, that the inhibition of GSTs reduces sperm quality and functionality parameters during their storage at 17 °C. These findings highlight the key role of such enzymes, especially preserving mitochondrial function and maintaining plasma membrane stability. In addition, this study has identified and localised GSTM3 in the tail and equatorial subdomain of the head of boar sperm. Finally, this study has set grounds for future investigations testing supplementation of semen extenders with GSTs, as this may improve fertility outcomes of swine AIs.

EFEKTIVITAS PENAMBAHAN EKSTRAK MESOCARP Borassus flabellifer PADA PENGENCER BELTSVILLE THAWING SOLUTION TERHADAP VIABILITAS SPERMATOZOA ASAL KAUDA EPIDIDIMIS BABI

This study aimed to determine the effectiveness of adding various concentrations of palm fruit mesocarp (Borassus flabellifer) extract to Beltsville Thawing Solution (BTS) diluents on the viability of swines cauda epididymis spermatozoa at 13°C for 4 days. During the storage period, the metabolic activity of spermatozoa will produce free radicals which can reduce spematozoa viability. Borassus flabellifer mesocarp extract contains antioxidants that can counteract free radicals. Testicular and epididymal samples from the 3-4 years old Duroc Landrace Swine Crossbreed. Swine cauda epididymis were obtained from the Oeba Abattoir, Kupang. Cauda epididymis spermatozoa were collected using a combination of incision, rinsing and suppression methods then collected and diluted using BTS and divided into four groups to be given various concentrations of Borassus flabellifer mesocarp extract (K0: without extract; K1: 0.01%; K2: 0.03%; and K3: 0.05 %) and preserved at 13°C for 4 days. Evaluation of spermatozoa viability was carried out microscopically. The results of cauda epididymis sperm viability were K0 = 43.57%; K1 = 54.81%; K2 = 50.52%; and K3 = 49.95%. Analysis of variance showed that the addition Borassus flabellifer mesocarp extract gave a significant difference (P> 0.05) to spermatozoa viability. The Duncan region test showed a significant difference (P <0.05) between treatment K1 with treatments K0, K2 and K3 on the viability of spermatozoa. The conclusions of this study was the addition of Borassus flabellifer mesocarp extract at 0.01% concentration was the most appropriate dose to maintain the viability of swine cauda epididymis spermatozoa. Keywords: Borassus flabellifer, Cauda Epididymal, Mesocarp Extract, Spermatozoa, Swine.

Deoxynivalenol reduces quality parameters and increases DNA damage in mice spermatozoa.

This study was performed to investigate in vitro effects of deoxynivalenol (DON) on mice sperm quality parameters including viability, motility and DNA damages at various concentrations and exposure times. Mice spermatozoa were exposed to DON at 0, 2.5, 5 and 10µM for 1, 3 and 6hr, motility parameters were evaluated by computer-assisted analysis and viability was examined by colorimetric metabolic activity assay and HOS test. DNA damage was examined by acridine orange staining, and sperm damages via lipid peroxidation pathway were determined by malondialdehyde (MDA) content measurement. DON affected sperm parameters in a concentration- and time-dependent manner. In all test groups, the average path velocity and progressive motile spermatozoa were remarkably reduced. In comparison with the controls, after 1, 3 and 6hr exposure to DON, viability of spermatozoa was reduced 25, 30 and 49% respectively. DON exposure at 10µM for 6hr resulted in 15% DNA damage and 2.5-fold more MDA generation, when compared with nonexposed spermatozoa. Our data suggest that DON causes sperm quality parameters decline in concentration- and time-dependent fashion, which attribute to the reduction in sperm metabolic activity and membrane integrity and equally to increase in lipid peroxidation rate and DNA damage.

Metabolic Activity of Boar Semen Stored in Different Extenders Supplemented with Ostrich Egg Yolk Lipoproteins.

IntroductionThe aim of this study was to evaluate the effect of lipoprotein fraction isolated from ostrich egg yolk (LPFo) on the metabolic activity of boar spermatozoa following liquid semen storage in different extenders and temperatures.Material and MethodsBoar ejaculates were extended in Androhep, Beltsville thawing solution (BTS), and Martín-Rillo and Alias (MR-A) without (control) or with the addition of LPFo and stored for three days at either 5°C or 16°C. The analysed sperm parameters included total motility (TMOT), plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), oxygen consumption, and adenosine triphosphate (ATP) production.ResultsThe sperm metabolic activity seemed to be higher in the LPFo-based extenders following storage for three days, irrespective of the storage temperature. Compared with the LPFo-free extenders, significantly higher (P < 0.05) sperm PMI and MMP were observed in BTS and MR-A extenders supplemented with LPFo during storage for three days at 5°C. Spermatozoa stored in the BTS-LPFo extender exhibited higher (P < 0.05) TMOT and oxygen consumption, whereas higher (P < 0.05) PMI was observed in spermatozoa stored in Androhep-LPFo and MR-A-LPFo for three days at 16°C. No significant differences (P > 0.05) in ATP content were observed between the LPFo-free and LPFo-based extenders during storage.ConclusionsSupplementation of LPFo to semen extenders had varying effects on the metabolic activity of boar spermatozoa stored at different temperatures. It can be suggested that the interactions of various components of the extenders and seminal plasma with LPFo exert beneficial effects on the sperm metabolic activity during liquid storage of boar semen.

Heat stress has an effect on motility and metabolic activity of rabbit spermatozoa

In the warm months the function of the spermatozoa can be affected by the temperature of the reproductive tract of the female exposed to hyperthermic conditions. The aim of this study was to evaluate the impact of heat stress on sperm parameters in an in vitro model and to determine if there were seasonal effects on sperm heat tolerance. Sperm samples from 32 New Zealand White rabbits were collected in two seasons and incubated at scrotal (32.5°C), body (37°C) or hyperthermic (42°C) temperatures for 3h. Sperm viability and morphology were evaluated using nigrosin-eosin staining. Motility and metabolic activity parameters were determined using computer-assisted sperm analysis and the QBlue cell viability test, respectively. The incubation of spermatozoa at 42°C decreased (P<0.05) the mean values of total motility, curvilinear (VCL) and mean velocity (VAP) as well as the metabolic activity with respect to the incubation at 32.5°C and 37°C.No seasonal effects were observed except for the highest percentages of bent and coiled tails in the cold season, and the highest mean values of VCL, linear velocity and VAP in the warm season (P<0.01). The interaction between in vitro heat stress and season was significant for metabolic activity (P=0.02). Our results suggest that rabbit spermatozoa parameters are largely modified by a short exposure to hyperthermic conditions, in terms of metabolic activity and motility parameters. Thus, a short exposure of spermatozoa to an environment of 42°C in temperature for only 3h may compromise sperm functionality. Additionally, sperm metabolic activity is influenced by season.

Seasonal-dependent variations in metabolic status of spermatozoa and antioxidant enzyme activity in the reproductive tract fluids of wild boar/domestic pig hybrids.

This study investigated seasonal changes in the metabolic performance of spermatozoa and activity of the antioxidant enzymes in the seminal plasma of three wild boar/domestic pigs (aged 1.5 to 2.5 years) and the activity of the antioxidant enzymes in fluids of the cauda epididymidis and vesicular glands from 16 wild boar/domestic pig hybrids (aged 1 to 3 years). Parameters of the sperm metabolic activity, such as total motility, mitochondrial functions, and measurements of oxygen uptake, ATP content and L-lactate production, were analyzed during the spring-summer and autumn-winter periods. Besides these sperm metabolic parameters, the sperm membrane integrity was also assessed. Total protein content and activity of the antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), were measured in the reproductive tract fluids. There were no marked significant differences (P > 0.05) between the seasonal periods in terms of sperm motility, mitochondrial function and oxygen uptake; however, spermatozoa collected during the autumn-winter period exhibited higher (P < 0.05) ATP content and L-lactate production than those harvested during the spring-summer period. It was found that the vesicular gland fluid exhibited a higher level of SOD activity during the spring-summer period compared with the autumn-winter period. Furthermore, CAT activity in the seminal plasma and vesicular gland fluid was greater during the autumn-winter. Total protein content was significantly higher in the vesicular gland fluid, whereas the cauda epididymidal fluid exhibited greater SOD and GPx activities, irrespective of the seasonal period. The findings of this study confirmed seasonal-related differences in the metabolic performance of spermatozoa and activity of antioxidant enzymes of the reproductive tract of the boar/domestic pig hybrids.

Effect of commercial long-term extenders on metabolic activity and membrane integrity of boar spermatozoa stored at 17°C

This study was aimed to analyze the metabolic activity and membrane integrity of boar spermatozoa following storage in long-term semen extenders. Boar semen was diluted with Androhep EnduraGuard (AeG), DILU-Cell (DC), SafeCell Plus (SCP) and Vitasem LD (VLD) extenders and stored for 10 days at 17 degrees C. Parameters of the analyzed sperm metabolic activity included total motility (TMOT), progressive motility (PMOT), high mitochondrial membrane potential (MMP) and ATP content, whereas those of the membrane integrity included plasma membrane integrity (PMI) and normal apical ridge (NAR) acrosome. Extender type was a significant (P < 0.05) source of variation in all the analyzed sperm parameters, except for ATP content. Furthermore, the storage time had a significant effect (P < 0.05) on the sperm metabolic activity and membrane integrity during semen storage. In all extenders the metabolic activity and membrane integrity of the stored spermatozoa decreased continuously over time. Among the four analyzed extenders, AeG and SCP showed the best performance in terms of TMOT and PMI on Days 5, 7 and 10 of storage. Marked differences in the proportions of spermatozoa with high MMP were observed between the extenders, particularly on Day 10 of storage. There were not any marked differences in sperm ATP content between the extenders, regardless of the storage time. Furthermore, the percentage of spermatozoa with NAR acrosomes decreased during prolonged storage, being markedly lower in DC-diluted semen compared with semen diluted with either AeG or SCP extender. The results of this study indicated that components of the long-term extenders have different effects on the sperm functionality and prolonged semen longevity by delaying the processes associated with sperm ageing during liquid storage.

Seasonal variations in metabolic activity of spermatozoa and antioxidant enzyme activity in the reproductive tract fluids of wild boar/domestic pig hybrids

Seasonal variations in metabolic activity of spermatozoa and antioxidant enzyme activity in the reproductive tract fluids of wild boar/domestic pig hybrids

Study of correlation between reaction time and refractory period (as indices of libido) with semen characteristics in ArkharMerino×Moghani and Baluchi×Moghani rams

This study was conducted on 10 crossbred rams consisted of 5 ArkharMerino×Moghani (AM×MG) and 5 Baluchi×Moghani (BL×MG), to analyze correlation between semen characteristics and libido activity. The semen samples were evaluated for semen volume, total sperm per ejaculate (TSE), spermatozoa concentration (SC), color, wave motion, spermatozoa progressive motility, percentage of live and abnormal spermatozoa, pH, rate of metabolic activity of spermatozoa and semen index. The libido of rams was measured by two indices including reaction time (RT) and refractory period (RP). While RT only had a negative and significant correlation with semen volume (r=−0.15, P=0.04), but RP had a significant correlation with seminal traits except for TSE. Moreover, libido test scores between two genetic groups did not have a significant difference (P<0.05). Considering the observed significant correlation between RP and semen characteristics, we suggest that a reliable monitoring with the aim of detecting rams of poor semen quality and libido seems worth making an effort for the future of the herd. In summary, the reported correlation between libido and seminal traits will confirm the importance of simultaneous selection for both libido and semen quality in the herd. Finally, the importance of performing an individual evaluation of semen and libido for each male and for using a ram in breeding programs is highlighted, due to the existence of differences among rams as well as a low correlation between semen characteristics and libido indices.

Characterization of lactate dehydrogenase enzyme in seminal plasma of Japanese quail ( Coturnix coturnix japonica)

Lactate dehydrogenase enzyme present in quail seminal plasma has been characterized. Polyacrylamide gel electrophoresis and subsequently with LDH specific staining of seminal plasma revealed a single isozyme in quail semen. Studies on substrate inhibition, pH for optimum activity and inhibitor (urea) indicated the isozyme present in the quail semen has catalytic properties like LDH-1 viz. H-type. Furthermore, unlike other mammalian species, electrophoretic and kinetic investigations did not support the existence of semen specific LDH-X isozyme in quail semen. The effect of exogenous lactate and pyruvate on sperm metabolic activity was also studied. The addition of 1 mM lactate or pyruvate to quail semen increased sperm metabolic activity. Our results suggested that both pyruvate and lactate could be used by quail spermatozoa to maintain their basic functions. Since the H-type isozyme is important for conversion of lactate to pyruvate under anaerobic conditions it was postulated that exogenous lactate being converted into pyruvate via LDH present in semen may be used by sperm mitochondria to generate ATP. During conversion of lactate to pyruvate NADH is being generated that may be useful for maintaining sperm mitochondrial membrane potential.

Comparative studies of canine semen freezing protocols.

The freezing of sperm is a method of conservation of spermatozoa, theoretically for an unlimited time. The freezing methods are an important tool for preservation of genetic diversity of the species and in assisted reproduction. The principle for cryopreservation of semen is reducing temperature of sperm determines a reduction of the metabolic activity of spermatozoa that permits their storage. A number of freezing methods have been described in the literature in the last 30 years. Some methods are registered marks and require buing a francise to be used. Proprietary agencies include Canine Cryobank, CLONE, International Canine Semen Bank (ICSB) and Synbiotics. Nonproprietary systems with published protocols include the Norwegian Tris extender, the Uppsala-Equex system 1 and 2 and its modifications, the CERREC extender, the CERCA extender, the extender developed by England C.G.W. and Lofstedt R. (Concannon and Battista 1989; England 1993; Farstad 1996; Linde- Forsberg et al. 1995; Pena and Linde-Forsberg 2000 a, b) and other extenders and cryopreservation methods.

Effect of different storage temperatures on the metabolic activity of spermatozoa following liquid storage of boar semen

This study investigated the effects of different temperatures (5o and 16oC) on the metabolic activity of boar spermatozoa preserved in a standard semen extender, Kortowo 3 (K3), supplemented with or without egg yolk lipoprotein fractions (LPF) isolated from hen or ostrich egg yolk. Besides motility and plasma membrane integrity (PMI) assessments of spermatozoa, analysis of the metabolic activity of spermatozoa included mitochondrial energy status, oxygen uptake, ATP content and L-lactate production. Total motility and PMI of spermatozoa decreased over time. The metabolic activity of spermatozoa was significantly higher in the extenders containing LPF than in the K3 extender. Marked changes in the sperm metabolic activity observed during storage of semen samples at 5oC indicated that glycolysis (fructolysis) was the major metabolic pathway. It seemed likely that mitochondrial respiration was the predominant metabolic activity exhibited by spermatozoa during storage at 16oC. The findings of this study indicate that different storage temperatures can modulate the metabolic pathways of boar spermatozoa during liquid semen storage.

Effect of rc Mutation on Semen Characteristics, Spermatogenic Tissues and Testosterone Profile in Blind Rhode Island Red Cockerels

Seven rc mutant and seven normal male birds (Rhode Island Red suie, RIR) were used in this study to determine the effects of rc mutation on semen characteristics, testosterone profile and spermatogenic tissues. All birds were randomly selected at week 12 of age and housed in individual cages and were fed and watered ad libitum. The birds were exposed to a 14L:10D light cycle during experiment. Semen were collected at weeks 22 to 23 from each bird twice a week and evaluated for semen volume (SV), sperm concentration (SC), total sperm count (TSC), percent of sperm motility (%SM), dead sperm (%DS), and sperm metabolic activity (SMA). To determine the testosterone concentration (TC) in plasma, blood was collected at weeks 12, 16 and 18. Testicular tissue were collected, processed and evaluated for semineferous tubule diameter (STD), round spermatid number (RSN), percent elongated sperm (%ES) and semineferous tubules length (STL). Body weight (BW), comb weight (CW) and testes weight (TW) were weighted at the end of experiment (week 23). The SV, TSC and %SM were significantly higher in normal birds but the %DS was higher in blind birds (p<0.05). The SC did not differ significantly between the two groups but its value was higher in normal birds. The sperm metabolic activity in the first h of collection did not differ significantly between the two groups but after 24 h, the level of SMA in normal group was significantly higher (p<0.05). The level of TC did not differ significantly between the two genotype groups but normal birds had higher TC in all collections except the last one. The STD, RSN, %ES and STL in normal birds were higher when compared to blind birds but the differences were insignificant except for ES percent. The BW, CW and TW between the two groups did not differ significantly but the weights were higher in normal group compared to blind birds. Statistical analysis of semen characteristics, testosterone profile and histological factors were indicated detrimental effects of rc mutation in prepubertal RIR blind male birds due to lack of light.

Lectin histochemistry of the boar bulbourethral glands.

The present study describes, for the first time, the glycosidic content of boar bulbourethral glands using lectin histochemistry. Fourteen horseradish peroxidase- or digoxigenin-labelled lectins with different carbohydrate specificities were used in samples obtained from 3 healthy Landrace boars. The results obtained indicate that endpiece and duct cells synthesize and secrete mainly O-glycoproteins with alpha- and beta-D-N-acetylgalactosamine, beta-D-galactose-beta(1-->3)-D-N-acetylgalactosamine, D-N-acetylglucosamine and neuraminic acid residues. Glycoproteins secreted by bulbourethral glands have a role in the protection and lubrication of the urethra. In addition, they may be also involved in the regulation of the sperm metabolic activity and in the maintenance of the structural integrity of acrosomal and plasma membranes.

Long-term preservation of chilled canine semen: effect of commercial and laboratory prepared extenders

The present study was conducted to evaluate chilled semen conservation over time in 3 commercial and 4 laboratory prepared extenders, including a new Tris-glucose extender. The beneficial effect of adding egg yolk to these media was also analyzed. The effects of these extenders on motility and acrosome reaction were characterized objectively using a computer-aided semen analyzer and the chlortetracycline staining, respectively. No significant differences were observed when comparing the different commercial extenders without egg yolk, but addition of egg yolk improved all motility parameters significantly (preservation of 50% of motility was observed at 3.2±1, 2.9±0.5, 2.3±0.5, 8.5±0.2, 5.4±1.1, 5.2±0.4 d, for Biladyl, green extender and fresh-phos extenders without and with egg yolk, respectively). Motility parameters were best preserved in egg yolk supplemented Biladyl extender with a mean percentage of 86.3±10.5 motile spermatozoa after 7 d at 4°C. Efficacy of egg yolk-supplemented commercial extenders on sperm motility at 4°C was (in decreasing order) as follows: Biladyl > green extender > fresh-phos. However, high quality motility and the percentage of motile spermatozoa were highest with some of the laboratory prepared extenders: a 50% conservation rate of motile spermatozoa was observed following the use of supplemented egg yolk extenders. These are classified in decreasing order as follows: Tris-glucose (13±1 d)> Tris-fructose 9.7±0.6) > EDTA (4. ±0.6 d) > Tris-bes (3.6±1.1 d). A low concentration of motile spermatozoa was still observed in the Tris-glucose egg yolk extender 16 d after collection, clearly demonstrating the importance of the medium and the beneficial effect of egg yolk on sperm motility of 4°C chilled semen. Similar effects of extender were observed for acrosome reactions. Egg yolk clearly had a protective effect reducing acrosome reactions significantly in all media tested as follows: the highest acrosome losses were observed in the fresh-phos and EDTA extenders without egg yolk; the lowest rate was observed with Tris-glucose supplemented egg yolk extender. In conclusion, at 4°C, egg yolk extender best-protected sperm motility parameters. Differences in osmolarity between the extenders in terms of substrate related to sperm metabolic activity may explain the optimal results obtained using egg yolk-supplemented Tris-glucose extender, which preserved motility and acrosome integrity in chilled dog semen. These results indicate that good quality dog spermatozoa could be preserved for up to 10 d.

Arginine Activates Glycolysis of Goat Epididymal Spermatozoa: An NMR Study

The present study explores the mechanism underlying the action of l-arginine on the metabolic activity of spermatozoa. Goat epididymal spermatozoa were incubated with different concentrations of l-arginine to determine its effect on the utilization of glucose, fructose, and pyruvate. NMR techniques have been applied to elucidate the effect of l-arginine, l-lysine, and l-ornithine on the glycolysis of epididymal goat spermatozoa. Whereas 31P NMR has been used to estimate the change of pH in the presence of different concentrations of l-arginine, 13C NMR has been used to estimate the substrate consumption and lactate production. At optimal concentration of l-arginine, the forward metabolic rates have been found to increase by two to three times over control experiments. Arginine is not consumed in these reactions, but acts as an activator. Longitudinal relaxation time ( T 1) measurements indicate that the guanidino group of l-arginine plays an active role in binding to cells. The amino acid l-lysine is less effective, and l-ornithine is ineffective.

Resazurin reduction assay for ram sperm metabolic activity measured by spectrophotometry.

Resazurin (7-hydroxy-3H-phenoxazin-3-one 10-oxide) is a redox dye that can be reduced by metabolically active spermatozoa to resorufin and manifested as visual color change from blue (resazurin) to pink (resorufin). This study combined the resazurin reduction test with spectrophotometric methods and investigated the correlation between metabolic activity and fertilization potential of spermatozoa, using ram semen as a model. The absorbance at specific wavelengths of resazurin and resorufin was determined by scanning photo spectrometer (600 nm for resazurin and 570 nm for resorufin, respectively). The absorbance at wavelengths of 600 nm (A600) and 570 nm (A570) was measured by spectrophotometry and used to evaluate sperm metabolic activity. A600 decreased and A570 increased in relationship to the increased concentrations of motile spermatozoa and increased resazurin reaction times. We observed, upon using a retrospective experimental design, that fertile rams had greater relative absorbance values than rams with lower fertility. Also, we observed a wide range variation of absorbance between the fertile rams, which is highly correlated to the sperm motility. We conclude that the spectrophotometric measurement of resazurin reduction for sperm activity might be a good assay for ram fertility.

Effect of dietary crude protein concentration on semen yield and quality in male broiler breeder fowls

Abstract 1. The responses in semen volume and spermatozoal concentration of 48 caged male broiler breeder fowls fed on a restricted quantity of food containing 80, 110, 152, 210, 290 or 400 g crude protein (CP)/kg from 18 to 64 weeks of age were studied. 2. The proportion of males producing semen declined with increasing dietary crude protein content and resulted in a significant decrease in total semen volume and spermatozoa production. 3. The relationship between the concentration of spermatozoa in the semen and dietary crude protein was negative but trivial. There were no relationships between dietary crude protein content and semen volume or the metabolic activity of spermatozoa. 4. The metabolic activity of spermatozoa was lower at 25 compared with 37 weeks of age. 5. The proportion of males giving semen peaked between 32 and 42 weeks of age. The relationship between age and semen volume and concentration of spermatozoa was negative and linear. 6. Blood plasma uric acid concentration increased linear...

Effect of cyclic AMP, imidazole and triiodothyronine on the rate of RNA synthesis by ejaculated ram spermatozoa

The effects of cyclic AMP (cAMP) and of triiodothyronine (T 3) on the enhancement of sperm motility and metabolism are well documented, and the present study was undertaken to investigate the mechanisms underlying these effects in terms of their influence on sperm RNA synthesis in vitro. Washed ram sperm were diluted to 1 40 (v/v) with incubation buffer that contained 100 μg/ml penicillin-G and 400 mg% glucose, followed by incubation at 37°C for a period of 4 h. Washed ram spermatozoa incubated with graded doses of cAMP (10 −8, 10 −6 and 10 −4 M) showed significant enhancements of the rate of 3H-uridine incorporation into RNA, with maximal effect occurring at 10 −8 M. The presence of 3.75, 7.50 or 15.00 μM T 3 also stimulated the rate of RNA synthesis by the washed ram sperm, with maximal effect occurring at 7.50 μM. On the contrary, imidazole (a compound known to stimulate phosphodiesterase activity and consequently to decrease the intracellular cAMP levels in many tissues) was found to cause consistent inhibition of spermatozoal RNA synthesis. The inhibition was 47, 90 and 92% of control for 10, 50 and 100 mM imidazole, respectively. The results obtained indicate that cAMP may act either as a first or a second messenger in the mature sperm. The data also indicate that T 3 (possibly mediated by cAMP) may act on the ram sperm by the induction of enzymes, which are required for the well-known effects of this hormone in enhancing the sperm metabolic activity.