Effects of dietary supplementation with L-arginine on the endogenous losses of amino acids in growing pigs exposed to heat stress.

Exposing pigs to heat stress (HS) provokes higher death of intestinal cells, resulting in elevated endogenous intestinal losses (EIL) of amino acids (AA) and damage to intestinal epithelia. Arginine (Arg) is precursor for the synthesis of polyamines, which are involved in proliferation of intestinal cells and restoration of the intestinal epithelia. Thus the effect of adding L-Arg to diets for HS pigs on the EIL of AA was analyzed. Twelve pigs (23.1 ± 1.1 kg body weight) implanted with T-type cannulas at the end of ileum were individually housed and allowed 15-days for surgery recovery under thermoneutral (TN) conditions (22 ± 2 °C). Following, the pigs were randomly assigned to one of three treatments: TN pigs fed a semi-purified, corn starch-3% casein basal diet (TN-B); HS pigs with the basal diet (HS-B); HS pigs consuming the basal diet supplemented with 0.20% L-Arg (HS-Arg). The experiment consisted of two 9-day periods; each period included 7-days of adaptation to their respective diet, followed by a 2-day ileal digesta collection period. Digesta was collected during 12 consecutive hours each day. The pigs were fed twice a-day. Ambient temperature (AT) inside the TN and HS rooms ranged from 18.6 to 27.6 °C and from 29.5 to 40.7 °C, respectively. Body temperature followed a pattern similar to that of AT. The daily EIL of indispensable AA increased (P < 0.01) in the HS-B pigs compared to both the TN-B and the HS-Arg pigs, however, there was no EIL difference between the TN-B and the HS-Arg pigs (P > 0.05). Likewise, with the exception of serine, daily losses of endogenous dispensable AA in the HS-B pigs were higher (P < 0.01) in comparison with those of TN-B and HS-Arg pigs. In summary, HS exposure compared to TN conditions increases the loss of endogenous AA, but dietary supplementation with L-Arg helped to counteract the negative HS effect.

Effect of dl-methionine supplementation above requirement on performance; intestinal morphology, antioxidant activity, and gene expression; and serum concentration of amino acids in heat stressed pigs.

The intestinal morphology and function can be compromised in pigs exposed to heat stress (HS), partly due to increased production of reactive-oxygen species. Because methionine (Met) functions as intracellular antioxidant, the requirement of Met may be increased in HS-pigs. The effect of dietary supplementation with dl-Met above requirement on performance, small intestine morphology, antioxidant enzymes activity, amino acid transporters expression, and serum concentration (SC) of free AA in HS-pigs was evaluated. A basal wheat-soybean meal diet was formulated to meet 100% Met requirement with the other indispensable AA exceeding at least 20% their requirement. Sixty individually housed pigs (23.0 ± 2.4 kg BW, 12 pigs per treatment) were randomly assigned to five treatments: TN100, thermal-neutral (22.7 °C) housed pigs fed the basal diet; HS100, HS120, HS140, HS160; HS-pigs (29.6 °C to 39.4 °C) fed the basal diet supplemented with dl-Met to contain 0%, 20%, 40%, and 60% dl-Met above the requirement, respectively. Pigs had free access to feed and water during the 21-d trial. Blood samples were collected on day 18 to analyze the absorptive AA-SC. The effect of ambient temperature (HS100 vs. TN100), as well as the linear and quadratic effects of increasing Met levels in the diets for HS-pigs were analyzed. The HS100 pigs gained less weight than TN100 and HS120 pigs (P < 0.01); gain:feed was also higher in HS120 pigs than in HS100 pigs (P ≤ 0.05). Feed intake of TN100 pigs was higher than that of HS-pigs fed the dl-Met supplemented diets (P < 0.05). Villi height reduced in pigs HS, but Met supplementation quadratically increased it (P < 0.05). Superoxide dismutase and catalase activities, reduced glutathione concentration, and relative expression of B0AT2 in ileum decreased (P < 0.05), but glutathione peroxidase activity increased in HS-pigs. dl-Met supplementation linearly affected catalase and glutathione peroxidase activities, as well as the relative expression of b0,+AT in jejunum (P < 0.05) of HS-pigs. The SC of Ile, Leu, Lys, Phe, and Val were higher in HS100 pigs than in TN100 pigs (P < 0.05). Graded levels of supplemental dl-Met in diets for HS-pigs linearly decreased SC of Ile, Leu, and Val (P < 0.05), tended to decrease His, Lys, and Thr (P < 0.10), and increased Met (P < 0.01). In conclusion, HS had negative effect on weight gain and intestinal morpho-physiology; however, it was ameliorated by adding 20% Met above the requirement in diets for growing pigs.

The exposure of pigs to ambient temperature above their comfort zone affects several functions of the small intestine, especially those related with digestion of feed and absorption of nutrients, which in turn reduces the availability of nutrients for growth. Amino acids such as methionine are involved in multiple functions of intestinal cells. Thus, methionine supplementation may help pigs to overcome the negative impact of their exposure to high ambient temperature. Indeed, methionine supplementation to the diet increased growth rate and feed efficiency of pigs housed under heat stress, which was presumably associated with an improvement in the utilization of the absorbed amino acids.

Apparent and standardised ileal amino acid digestibilities in heat-stressed pigs fed wheat-soybean meal diets supplemented with l-arginine and dl-methionine.

Heat stress (HS) exposure may damage the small intestine epithelia of pigs affecting the digestibility and absorption of amino acids (AA). Arg and Met can enhance antioxidant and intestinal cell proliferation activity, thus supplementing them in diets might alleviate epithelial damage and correct the reduced AA digestibility. The effect of adding extra l-Arg and dl-Met to diets on the apparent (AID) and standardised ileal digestibility (SID) of AA was analysed in a 10-day experiment conducted with 10 ileal-cannulated HS pigs (25.3 ± 2.4 kg body weight). The pigs were divided into two treatments: Control, wheat-soybean meal diet supplemented with l-Lys, l-Thr, dl-Met and l-Trp; and control diet plus 0.20% l-Arg and 0.20% dl-Met (Arg + Met). Following an 8-day diet adaptation period, ileal digesta was continuously collected for 12 h, starting at 0700, on Days 9 and 10. All pigs were daily exposed to 29.6-36.1°C; ileal temperature was continuously monitored at 15-min intervals. Feed was provided twice a day. The ileal temperature ranged from 40.3 to 41.5°C. Daily ileal outflow of His, Ile, Leu, Phe, Thr, Ser and Tyr decreased (p < 0.05), and that of Arg, Val and Pro tended to decrease (p < 0.10) in the Arg + Met pigs. The AID of Arg, His, Met, Thr and Tyr, and the SID of His, Met, and Thr increased in pigs fed the Arg + Met diet (p < 0.05). Thr and Val had the lowest AID values whereas Arg, Met, and Lys had the highest values. Arg (r = 0.64) and Met (r = 0.84) intake were highly correlated with their AID values; Met intake was highly correlated with its SID value (r = 0.72). Valine and Arg had the lowest whereas Arg had the highest SID values. In conclusion, supplementing l-Arg and dl-Met above the requirement decreases the ileal outflow of several AA, and increases the AID and SID of some essential AA in HS pigs.

Protein potential of Desmodesmus asymmetricus grown in greenhouse as an alternative food source for aquaculture.

During ten months, batch culture of Desmodesmus asymmetricus microalgae was carried out under greenhouse conditions. The inoculation ratio was 1:1 (inoculum:treated water). The cultures were maintained for 5 days with natural light and constant aeration mixed with carbon dioxide. The biomass was concentrated by centrifugation and dried by lyophilization; subsequently, total proteins and amino acid concentration were quantified. A relationship between biomass production and seasonal variation was observed, the lowest dry biomass production was recorded in June (38.8 ± 1.0 mg L-1 day-1) and July (43.3 ± 0.1 mg L-1 day-1); while the highest values ​​were greater than 70 mg L-1 day-1 in March. There was a high positive correlation between wet and dry biomass (r = 0.97, p < 0.001) with a mean conversion of 26%. The mean percentage of protein was 26.1 ± 2.6%, the highest percentage was registered in March (31.03 ± 1.48%) as well as the concentration of amino acids. Regarding amino acids, arginine obtained the highest concentration (4.08 ± 0.43 g 100 g-1), followed by aspartic acid (3.36 ± 0.23 g 100 g-1), while the lowest values were for methionine (0.55 ± 0.21 g 100 g-1), histidine (0.77 ± 0.07 g 100 g-1) and tyrosine (1.01 ± 0.17 g 100 g-1). Finally, according to the essential amino acid index (in fish ≥ 0.90, in crustaceans > 0.80), the biomass of D. asymmetricus has potential as a food supplement for the production of feed in aquaculture.

Effect of arginine supplementation on the morphology and function of intestinal epithelia and serum concentrations of amino acids in pigs exposed to heat stress.

The exposure of pigs to heat stress (HS) appears to damage their intestinal epithelia, affecting the absorption of amino acids (AAs). Arg is involved in the restoration of intestinal epithelial cells but HS reduces Arg intake. The effect of dietary supplementation with Arg on the morphology of intestinal epithelia, AA transporter gene expression, and serum concentration (SC) of free AAs in HS pigs was analyzed. Twenty pigs (25.3 ± 2.4 kg body weight) were randomly assigned to two dietary treatments: Control (0.81% Arg), wheat-soybean meal diet supplemented with l-Lys, l-Thr, dl-Met, and l-Trp, and the experimental diet where 0.16% free l-Arg was supplemented to a similar Control diet (+Arg). All pigs were individually housed and exposed to HS, fed ad libitum with full access to water. The ambient temperature (AT), recorded at 15-min intervals during the 21-d trial, ranged on average from 29.6 to 39.4 °C within the same day. Blood samples were collected on day 18 at 1600 hours (AT peak); serum was separated by centrifugation. At the end of the trial, five pigs per treatment were sacrificed to collect samples of mucosa scratched from each small intestine segment. The expression of AA transporters in intestinal mucosa and the SC of AAs were analyzed. Villi height (VH) was higher (P < 0.01) in the duodenum, jejunum, and ileum but the crypt depth did not differ between the Control and the +Arg pigs. Supplementation of l-Arg increased the mRNA coding for the synthesis of the cationic AA transporter b0,+ (P < 0.01) and the neutral AA transporter B0 (P < 0.05) in the duodenum by approximately 5-fold and 3-fold, respectively, but no effect on mRNA abundance was observed in the jejunum and ileum. The supplementation of l-Arg increased serum Arg, His, Met, Thr, Trp, and urea (P < 0.05) and also tended to increase Val (P < 0.10) but did not affect Ile, Lys, Leu, and Phe. These results indicate that supplementing 0.16% l-Arg to the Control diet may help to improve the function of the small intestine epithelium, by increasing the VH, the abundance of AA transporters, and the SC of most indispensable AAs in pigs exposed to HS conditions. However, the lack of effect of supplemental Arg on both Lys SC and weight gain of pigs suggests that increasing the Lys content in the +Arg diet might be needed to improve the performance of HS pigs.

Melatonin Decreases Circulating Levels of Galectin-3 and Cytokines, Motor Activity, and Anxiety Following Acute Global Cerebral Ischemia in Male Rats.

BACKGROUND: Global cerebral ischemia (GCI) elicits damages to cerebral structures, learning dysfunction, memory impairments, hyperactivity, and anxiety. Circulating levels of galectin-3 (Gal-3) are associated with patient severity and outcome. AIM: To report circulating levels of Gal-3, and cytokines (TNF-α, IL-6, IL-10) in the initial hours (acute) following GCI in a four-vessel occlusion (4-VO) rat model and the effect of melatonin treatment. METHODS: 4-VO model was used to produce GCI using male Sprague-Dawley rats. Groups were: Sham-Veh, Sham-Mel, Isch-Veh and Isch-Mel. Melatonin was administered 30 min after carotid clamp removal. Gal-3 and cytokines levels were measured at 0, 30 min, 6 h and 24 h after the end of cerebral flow interruption using ELISA kits. Motor activity and anxiety were measured using open-field test. RESULTS: Acute GCI (AGCI) followed by reperfusion decreased serum concentrations of TNF-α and increased IL-6 levels 24 h after ischemia, whereas melatonin reduced significantly the concentrations of these cytokines. In all groups IL-10 was higher 30 min and negligible at other times. Circulating levels of Gal-3 were reduced 30 min after ischemia/reperfusion. In the Isch-Mel group the neuroprotective effect generated a reduction in circulating Gal-3 at 6 and 24 h after AGCI, compared with all the groups. Motor activity was increased due to ischemic reperfusion, but acute melatonin treatment reduced locomotion, similar to the control group. Anxiety was reduced in the melatonin group. CONCLUSIONS: Melatonin treatment following AGCI reduces pro-inflammatory factors, Gal-3, motility, and anxiety, therefore it should be considered as supplementary treatment following ischemic stroke.

Effect of aqueous extracts of Ficus vogeliana Miq and Tieghemella africana Pierre in 7,12-Dimethylbenz(a)anthracene -induced skin cancer in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Skin cancer is the most common form of cancer responsible for considerable morbidity and mortality. Tieghemella africana and Ficus vogeliana are used in traditional medicine to treat cancers. AIM OF THE STUDY: Therefore, the aim of this study was to investigate the antioxidant, antiangiogenic and anti-tumor activities of these plant extracts. MATERIALS AND METHODS: To achieve it, phytochemical screening, antioxidant activity and antiangiogenic activity were assessed. Thereafter, the anti-tumor activity was determined using skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene. RESULTS: The phytochemical result analysis showed that both plant extracts were rich in polyphenols, alkaloids and terpene compounds and possessed good antioxidant activity based on DPPH radical scavenging (IC50 = 9.70 µg/mL and 4.60 µg/mL and AAI values of 5.20 and 10.88) and strong total antioxidant capacity (115.44 VtCE (mg)/g of dry plant extract and 87.37 VtCE (mg)/g of dry plant extract, respectively). Additionally, both plant extracts possessed antiangiogenic activities (IC50 = 53.43 µg/mL and 92.68 µg/mL, respectively), which correlated with significant antitumor activities when using 35 mg/kg (65.02% and 77.54%) and 70 mg/kg of extracts (81.07% and 88.18%). CONCLUSIONS: In summary, this study illustrates the promising usage of Tieghemella africana and Ficus vogeliana plant extracts in treating skin cancer. However, further characterization of the extracts must be performed to isolate the most active anticancer compound.

Dietary protein-bound or free amino acids differently affect intestinal morphology, gene expression of amino acid transporters, and serum amino acids of pigs exposed to heat stress.

Pigs exposed to heat stress (HS) increase body temperature in which can damage the intestinal epithelia and affect the absorption and availability of amino acids (AA). Protein digestion and metabolism further increase body temperature. An experiment was conducted with six pairs of pigs (of 47.3 ± 1.3 kg initial body weight) exposed to natural HS to assess the effect of substituting dietary protein-bound AA by free AA on morphology and gene expression of intestinal epithelial and serum concentration (SC) of free AA. Treatments were: high protein, 21.9% crude protein (CP) diet (HShp) and low protein, 13.5% CP diet supplemented with crystalline Lys, Thr, Met, Trp, His, Ile, Leu, Phe, and Val (HSaa). The HShp diet met or exceeded all AA requirements. The HSaa diet was formulated on the basis of ideal protein. Pigs were fed the same amount at 0700 and 1900 hours during the 21-d study. Blood samples were collected at 1700 hours (2.0 h before the evening meal), 2030 hours, and 2130 hours (1.5 and 2.5 h after the evening meal). At the end, all pigs were sacrificed to collect intestinal mucosa and a 5-cm section from each segment of the small intestine from each pig. Villi measures, expression of AA transporters (y+L and B0) in mucosa, and SC of AA were analyzed. Ambient temperature fluctuated daily from 24.5 to 42.6 °C. Weight gain and G.F were not affected by dietary treatment. Villi height tended to be larger (P ≤ 0.10) and the villi height:crypt depth ratio was higher in duodenum and jejunum of pigs fed the HSaa diet (P < 0.05). Gene expression of transporter y+L in jejunum tended to be lower (P < 0.10) and transporter B0 in the ileum was lower (P < 0.05) in HSaa pigs. Preprandial (1700 hours) SC of Arg, His, Ile, Leu, Thr, Trp, and Val was higher (P < 0.05), and Phe tended to be higher (P < 0.10) in HShp pigs. At 2030 hours (1.5 h postprandial), serum Lys, Met, and Thr were higher in the HSaa pigs (P < 0.05). At 2130 hours (2.5 h), Arg, His, Ile, Phe, and Trp were lower (P < 0.05); Met was higher (P < 0.05); and Lys tended to be higher (P < 0.10) in HSaa pigs. In conclusion, feeding HS pigs with low protein diets supplemented with free AA reduces the damage of the intestinal epithelia and seems to improve its absorption capacity, in comparison with HS pigs fed diets containing solely protein-bound AA. This information is useful to formulate diets that correct the reduced AA consumption associated with the decreased voluntary feed intake of pigs under HS.

Extra dietary protein-bound or free amino acids differently affect the serum concentrations of free amino acids in heat-stressed pigs1.

Pigs exposed to heat stress (HS) reduce feed intake and consequently the consumption of AA. Adding extra protein-bound or free AA to the diet may correct the reduced AA intake of HS pigs. However, extra protein-bound AA may further increase the body heat load, whereas extra free AA does not affect the heat load of HS pigs. Two experiments were conducted. In Exp. 1, the performance depression because of HS, compared with thermal neutrality, was determined with 30 pigs (31.1 ± 1.2 kg BW) fed diets with AA only as protein or as a mix of protein and free AA. Heat stress pigs consumed 18 to 25% less Lys and Thr than thermal neutral. In Exp. 2, the effect of extra dietary protein-bound or free AA on performance and serum concentration of AA in 25 HS pigs (33.6 ± 0.65 kg BW) was evaluated. Treatments were as follows: CON, wheat-soybean meal-free Lys-Thr-Met diet; xP diet, 26% more protein than the CON diet; xAA diet, 24% or more of each AA than the recommended level. Pigs were fed ad libitum. Blood samples were collected between 1600 and 1700 h, when pigs were exposed to the highest ambient temperature (around 41.3 °C). Body temperature ranged daily from 39.9 to 41.1 °C. The performance data were reported already. Pigs fed the xP diet consumed more of all indispensable AA and dispensable AA than the CON pigs (P < 0.05), and more Arg, Ile, Asp, Glu, Gly, and Ser (P < 0.05) than the xAA pigs. Except for Arg, xAA pigs consumed more indispensable AA than the CON pigs (P < 0.05). Serum Arg, His, Lys, Phe, Thr, Trp, and Val, was higher (P < 0.05) in xP than in CON pigs. Except for Ile serum, indispensable AA were higher in xAA than in CON pigs (P < 0.05). Serum Ile, Leu, Thr, and Val were higher (P < 0.05), and Met tended to be higher (P < 0.10) in xAA than in xP pigs. The difference of Ile, Leu, Met, Thr, and Val between the CON and the xAA pigs was larger than that between the CON and the xP pigs (P < 0.05). Serum Asn and Tyr were higher, and Cys and Glu were lower (P < 0.05) in xP than in CON pigs. Serum Cys tended to be lower in xAA than in CON pigs (P < 0.10). Asp and Glu were higher (P < 0.05) in xAA pigs than in xP pigs. In conclusion, these serum AA results combined with the reported performance data indicate that extra free AA in diets for HS pigs may help to correct the reduced AA availability and performance of HS pigs, although higher levels of specific AA such as Ile and Met might be needed.

Serum concentrations of free amino acids in growing pigs exposed to diurnal heat stress fluctuations.

In areas where the ambient temperature (AT) is above the thermo neutral (TN) zone of pigs, significant changes within a 24-h period occur, differently affecting the availability of amino acids (AA) within the same day. An experiment was conducted to analyze the serum concentrations (SC) of free AA in pigs exposed to diurnal variations in AT. Six pigs (27.1 ±1.3kg body weight) implanted with a thermometer to register the body temperature (BT) at 15-min intervals were used. Blood samples were collected on the last 3 d of the 14-d study, at 0700h (lowest AT), 1200h (mild HS), and 1600h (severe HS). The pigs received 1.2kg/d of an AA-supplemented, wheat-soybean meal diet, in two equal meals (0700 and 1900h). The AT and BT, recorded at 0700, 1200, and 1600h was: 30.6, 38.6, 41.1°C, and 38.2, 39.5, 40.3°C, respectively. The BT was significantly correlated (P < 0.001) with the AT. The SC (µM/mL) of Ile, Lys, Met, Val, Ala, Asn, and Pro were higher (P ≤ 0.01); Arg, Phe, Glu, and Tyr tended to be higher (P ≤ 0.10); but Cys was lower (P < 0.05) at 1200h than at 0700h. Lys was higher, Cys and Tyr were lower (P < 0.05), and Ile and Val tended to be higher (P ≤ 0.10) at 1600h than at 0700h. Serum Arg, Ile, Phe, Ala, Asn, Gln, Pro, Ser, and Tyr were lower (P < 0.05), and Leu and Val tended to be lower at 1600h than at 1200h. These data demonstrate that AT directly alters the BT of pigs, and that diurnal variations in AT differently affect their SC and availability of AA for growth.

Plastic changes in dendritic spines of hippocampal CA1 pyramidal neurons from ovariectomized rats after estradiol treatment.

Cognitive impairment or its recovery has been associated with the absence or reestablishment of estrogenic actions in the central nervous system of female experimental animals or women. It has been proposed that these cognitive phenomena are related to estrogen-mediated modulatory activity of synaptic transmission in brain structures involved in cognitive functions. In the present work a morphological study was conducted in adult female ovariectomized rats to evaluate estradiol-dependent dendritic spine sprouting in hippocampal pyramidal neurons, and changes in the presynaptic marker synaptophysin. Three or ten days after estradiol treatment (10 µg/day, twice) in the ovariectomized rats, a significant increase of synaptophysin was observed, which was coincident with a significant higher numerical density of thin (22%), stubby (36%), mushroom (47%) and double spines (125%), at day 3, without significant changes of spine density at day 10, after treatment. These results may be interpreted as evidence of pre- and postsynaptic plastic events that may be involved in the modulation of cognitive-related behavioral performance after estrogen replacement therapy.

Cytoarchitectural characteristics of hippocampal CA1 pyramidal neurons of rats, four months after global cerebral ischemia and progesterone treatment.

PURPOSE: To analyze the cytoarchitectural characteristics of the remaining pyramidal neurons in the hippocampal CA1 subfield of rats, four months after global cerebral ischemia (GCI) and progesterone treatment. METHODS: Dendritic arborization, and density and shape of the dendritic spines of CA1 pyramidal neurons in brains of intact rats, or rats submitted 120 days earlier to GCI and treatment with progesterone (8 mg/kg) or its vehicle, at 15 min, and 2, 6, 24, 48, and 72 h after the onset of reperfusion, were analyzed in samples processed by a modified Golgi method. RESULTS: Few impregnated CA1 pyramidal neurons were identified in the ischemic vehicle-treated rats, with a short apical dendrite devoid of bifurcations and dendritic spines. In contrast, the remaining CA1 pyramidal neurons sampled from ischemic progesterone-treated rats showed sinuously branched dendrites with similar number of bifurcations and whole density of spines, and higher proportional density of mushroom spines than those in the intact group. CONCLUSIONS: These cytoarchitectural characteristics may underlie the long-term preservation of place learning and memory functions seen after ischemia and progesterone neuroprotective treatment, possibly compensating for the severe reduction in neuronal population.

Long-term study of dendritic spines from hippocampal CA1 pyramidal cells, after neuroprotective melatonin treatment following global cerebral ischemia in rats.

Melatonin reduces pyramidal neuronal death in the hippocampus and prevents the impairment of place learning and memory in the Morris water maze, otherwise occurring following global cerebral ischemia. The cytoarchitectonic characteristics of the hippocampal CA1 remaining pyramidal neurons in brains of rats submitted 120 days earlier to acute global cerebral ischemia (15-min four vessel occlusion, and melatonin 10mg/(kg h 6h), i.v. or vehicle administration) were compared to those of intact control rats in order to gain information concerning the neural substrate underlying preservation of hippocampal functioning. Hippocampi were processed according to a modification of the Golgi method. Dendritic bifurcations from pyramidal neurons in both the oriens-alveus and the striatum radiatum; as well as spine density and proportions of thin, stubby, mushroom-shaped, wide, ramified, and double spines in a 50 microm length segment of an oblique dendrite branching from the apical dendrite of the hippocampal CA1 remaining pyramidal neurons were evaluated. No impregnated CA1 pyramidal neurons were found in the ischemic-vehicle-treated rats. CA1 pyramidal neurons from ischemic-melatonin-treated rats showed stick-like and less ramified dendrites than those seen in intact control neurons. In addition, lesser density of spines, lower proportional density of thin spines, and higher proportional density of mushroom spines were counted in ischemic-melatonin-treated animals than those in the sinuously branched dendrites of the intact control group. These cytoarchitectural arrangements seem to be compatible with place learning and memory functions long after ischemia and melatonin neuroprotection.

Maize cDNAs expressed in endosperm encode functional farnesyl diphosphate synthase with geranylgeranyl diphosphate synthase activity.

Isoprenoids are the most diverse and abundant group of natural products. In plants, farnesyl diphosphate (FPP) and geranylgeranyl diphosphate (GGPP) are precursors to many isoprenoids having essential functions. Terpenoids and sterols are derived from FPP, whereas gibberellins, carotenoids, casbenes, taxenes, and others originate from GGPP. The corresponding synthases (FPP synthase [FPPS] and GGPP synthase [GGPPS]) catalyze, respectively, the addition of two and three isopentenyl diphosphate molecules to dimethylallyl diphosphate. Maize (Zea mays L. cv B73) endosperm cDNAs encoding isoprenoid synthases were isolated by functional complementation of Escherichia coli cells carrying a bacterial gene cluster encoding all pathway enzymes needed for carotenoid biosynthesis, except for GGPPS. This approach indicated that the maize gene products were functional GGPPS enzymes. Yet, the predicted enzyme sequences revealed FPPS motifs and homology with FPPS enzymes. In vitro assays demonstrated that indeed these maize enzymes produced both FPP and GGPP and that the N-terminal sequence affected the ratio of FPP to GGPP. Their functionality in E. coli demonstrated that these maize enzymes can be coupled with a metabolon to provide isoprenoid substrates for pathway use, and suggests that enzyme bifunctionality can be harnessed. The maize cDNAs are encoded by a small gene family whose transcripts are prevalent in endosperm beginning mid development. These maize cDNAs will be valuable tools for assessing the critical structural properties determining prenyl transferase specificity and in metabolic engineering of isoprenoid pathways, especially in cereal crops.

Effect of phytase supplementation to diets for wealing pigs on the utilization of phosphorus and calcium

Se realizaron cuatro experimentos con cerdos destetados para determinar el efecto de la adición de fitasa a cuatro tipos de dietas en la digestibilidad total aparente y retención de P y Ca. La fitasa se adicionó en 0, 500 y 1000 FTU/kg de las cuatro dietas. En el Exp. 1 se utilizó una dieta maíz-pasta de soya, 20 por ciento proteína cruda (PC); dieta trigo-pasta de soya, 20 por ciento CP en Exp. 2; dieta trigo-pasta de soya-pasta de canola, 20 por ciento CP en Exp. 3; y cebada-garbanzo-pasta de canola, 19 por ciento PC en Exp. 4. Se usaron 6 cerdos en cada experimento y se alimentaron con las dietas base o las adicionadas con fitasa de acuerdo con un diseño en cuadro latino 3x3 repetido. Cada periodo experimental consistió de 14 días. Los cerdos se alimentaron a las 08:00 y 20:00, en cantidades iguales cada comida, equivalentes al menos a 2,4 veces las necesidades diarias de energía metabolizable. Las heces y orina se colectaron de 08:00 del día 8 a las 08:00 del día 12 de cada periodo experimental. La adición de fitasa, aún a dietas adicionadas con P inorgánico, aumenta la digestibilidad de P y reduce su excreción en heces. La respuesta a fitasa en la utilización de Ca varía con la composición de la dieta y es dependiente de su contenido de Ca. La adición de 1000 FTU/kg dieta, comparado con la de 500 FTU/kg dieta no resultó en una mejora adicional en la utilización de P y Ca

Effect of phytase supplementation to barley-canola meal and barley-soybean meal diets on phosphorus and calcium balance in growing pigs

Se realizaron dos experimentos metabólicos para determinar el efecto de adicionar una fitasa microbiana a dietas cebada pasta de canola y cebada-pasta de soya en el balance de P y Ca de cerdos en crecimiento. En el experimento 1, seis cerdos (29,6kg peso vivo inicial) se alimentaron con dietas elaboradas con cebada y pasta de canola, sin o con fitasa (500 unidades.kg-¹ dieta) durante 24 días, en un diseño de sobrecambio. Las dietas proveyeron niveles de P inferior es al óptimo. En el experimento 2, doce cerdos (53,5kg peso vivo inicial) recibieron 4 dietas cebada-pasta de soya, en un diseño de sobrecambio con dos periodos experimentales. Las dietas 2, 3 y 4 contenían niveles de P inferiores al óptimo. La dieta 1 se adicionó con P y Ca inorgánico para cubrir los requerimientos; las dietas 2, 3 y 4 contenían niveles de P inferiores al óptimo, acondicionándose la dieta 3 con fitasa y la dieta 4 con fitasa y una mezcla de xilanasa y ß-glucanasa. La adición de fitasa incrementó (p<0,05) la digestibilidad y la retención de P, así como la digestibilidad de Ca. La adición conjunta de fitasa y mezcla de xylanasa y ß-glucanasa a la dieta 2 produjo valores de retención de P y digestibilidades de P y Ca similares (P> 0,05) a los de las dietas 1 y 3. En conclusión, la adición de fitasa a dietas cebada-pasta de canola y cebada-pasta de soya mejoró la utilización de P y la digestibilidad de Ca, pero no se obtuvo efecto adicional con la adición de xylanasa y ß-glucanasa

Modifications of acoustic habituation by interruption of visual imput in quipazine treated cats

En el presente trabajo se estudian las consecuencias de la interrupción de la información visual aferente sobre la habituación acústica provocada antes e inmediatamente después de la administración de quipazina, 3 mg/kg iv, en gatos. Las características de la habituación acústica se han analizado mediante la magnitud y el curso temporal de las respuestas de la actividad multiunitaria (MUA) inducidas en la formación reticular mesencefálica (MRF) por estímulos acústicos repetidos a intervalos de 10 seg (grupos de ondas zonoras, 50 Hz, 70 db; de 2 seg de duración) en 6 gatos machos implantados a permanencia con electrocos en la corteza parietal, MRF y amígdala basolateral (AMN)

Comprobación electrofisiológica de "conducta de relajación" durante la succión en gatas lactantes / Electrophysiological evidence of relaxation behavior during suckling in lactating female cats

La ingestión y la succión de leche indujeron sincronización del EEG (6-10 cps, 150-180 v) en el área parietooccipital y el hipocampo coincidente con inhibición de la actividad multiunitaria (MUA) de la formación reticular mesencefálica, el hipocampo dorsal y los núcleos hipotalámicos ventromedial y paraventricular. las proporciones de sincronización EEG variaron en diferentes animales (20 gatas lactantes) de 2 por ciento a 60 por ciento del tiempo total de succión, o de 3 por ciento a 77 por ciento del tiempo total de ingestión de leche. La presencia y la magnitud de la sincronización EEG durante la succión no tienen relación con el rendimiento lácteo, pero parecen estar relacionadas con el estado de ánimo de las gatas, espontáneo o inducido por fármacos. Los cambios del EEG y la MUA provocados por la succión son idénticos a las manifestaciones electrográficas de la "conducta de relajación" de los gatos durante ingestión de leche, acicalamiento, estimulación perineal o acariciamiento; de este modo, puede concluirse que son parte de la reacción integral de las gatas lactantes ante los estímulos de la succión, los cuales producen "conducta de relajación""

Efectos del diacepam y del metocarbamol sobre los signos EEG de la "conducta de relajación" inducida por la ingestión de leche en gatos / Effects of diazepam and methocarbamol on EEG signs of relaxation behavior induced by milk slurping in cats

Se investigaron los efectos de diferentes dosis de diacepam (0.1,0.3,1.0,3.0 mg/kg IM) o metocarbamol (30,100,300 mg/kg IM) en diez gatos que mostraban comportamiento aprensivo y escasas proporciones de sincronización del EEG parietal y parietooccipital durante la ingestión de leche, un signo electrografico confiable de la "conducta de relajación" en el gato. Las proporciones de sincronización del EEG parietal y parietooccipital aumentaron significativamente luego de la administración de estos fármacos; al parecer este efecto del diacepam se relaciona principalmente con los efectos del fármaco sobre la conducta que también suprimió el comportamiento aprensivo. El efecto del metocarbamol, aumentó de la sincronización del EEG durante la ingestión de leche, podría ser causado principalmente por cambios del estado de ánimo resultantes de la relajación muscular. Estos hallazgos deben considerarse para el análisis de los mecanismos nerviosos que relacionan el estado de ánimo, el tono muscular y los signos electrográficos de la "conducta de relajación