Castrated Males Research Articles

Diet and sexual hormones regulate hepatic synaptotagmin 1 mRNA in mice.

The expression of Synaptotagmin 1 (Syt1) has been found to be associated with the lipid droplets in liver. Here, we studied the expression of Syt1 in Apoe-deficient mice receiving cholesterol, Western diet, squalene, and oleanolic acid. We also studied the influence of sex and impact of surgical castration. Dietary cholesterol increased hepatic Syt1 expression, an effect that was enhanced when cholesterol was combined with saturated fat present in a Western diet. This potentiation was modified by the administration of 10 mg/kg oleanolic acid or 1 g/kg squalene. Females fed chow or Western diet showed higher levels of hepatic Syt1 expression as compared to male mice on the same diet. Surgical castration of males did not modify the Syt1 expression; however, ovariectomy led to decreased levels. The data show that hepatic Syt1 expression is influenced by diet and hormonal milieu.

Androgen-primed castrate males are sufficient for methamphetamine-facilitated increases in proceptive behavior in female rats

Methamphetamine (MA) is a psychomotor stimulant associated with increases in sex drive in both men and women. Women, however, are far more likely to face social disadvantages as a consequence of MA use, and their increased sexual motivation poses additional health concerns such as unplanned pregnancies. To better understand the mechanisms underlying MA-facilitated sexual motivation in females, we previously established a rodent model where a “binge”-type administration paradigm of MA to sexually receptive female rats significantly increases proceptive behavior in the presence of a sexually active, gonadally-intact male. Our previous work with this model has led us to consider whether the increases in proceptive behavior are truly indicative of increased sexual motivation, or instead a consequence of heightened motor responsivity. Here, we test whether MA-induced increases in proceptive behaviors are specific to a sexually relevant stimulus. Females' sexual, social, exploratory behaviors, and interaction times were scored during the exposure to stimulus males, including castrates, and dihydrotestosterone (DHT)-treated castrates. MA-treated females demonstrated significant increases in proceptive behaviors toward DHT-treated castrate males but not toward castrate males. While the non-MA-treated females did display proceptive behavior, there was no significant difference between behaviors elicited by DHT-CX males compared to CX males. Our results support the hypothesis that MA facilitates proceptive behavior only in response to specific, androgen mediated sexually-relevant cues.

Relationship between male hormonal status, Bezold-Jarisch reflex function, and ACE activity (cardiac and plasmatic).

The negative relationship between androgens and the Bezold-Jarisch reflex (BJR) has been demonstrated, but no studies evaluated the physiological influence of testosterone on this reflex. We evaluated the influence of male rat castration on the BJR, cardiac morphometric parameters, and the plasmatic and the cardiac angiotensin converting enzyme (ACE) activity. After castration (CAS), the rats were divided into 24 and 72 h (CAS24H, CAS72H), and 7 and 21 days (CAS7D, CAS21D) groups. The BJR was studied by administering increasing doses of phenylbiguanide (PBG; 1.5-24 μg/kg) at different times after castration. Castration results in the following: (i) reduction in testosterone levels (SHAM: 238.7 ± 15.1; CAS24H: 9.0 ± 0.5; CAS72H: 6.7 ± 0.4; CAS7D: 5.2 ± 0.2; and CAS21D: 2.2 ± 0.3 ng/dL; p < 0.05); (ii) no changes in 17β-estradiol; (iii) a reduced BJR sensitivity (PBG 6 μg/kg; SHAM: 77 ± 7; CAS24H: 63 ± 10; CAS72H: 55 ± 6; CAS7D: 54 ± 4; and CAS21D: 35 ± 2%; p < 0.01); (iv) a decrease in cardiac (SHAM: 107 ± 6; CAS24H: 92 ± 2; CAS72H: 82 ± 3; CAS7D: 54 ± 3; and CAS21D: 43 ± 4%; p < 0.05) and plasmatic (SHAM: 135 ± 8; CAS24H: 102 ± 5; CAS72H: 99 ± 3; CAS7D: 89 ± 4; and CAS21D: 56 ± 6%; p < 0.05) ACE activity. No changes were observed in cardiac morphometry and hemodynamic parameters. Therefore, castration leads to decrease in testosterone levels as early as 24 h, reduction in ACE activity and loss of BJR sensitivity 7 days after castration. The loss of BJR sensitivity was not related to cardiac morphometric changes and cardiovascular hemodynamics.

Tolerance evaluation of overdosed dietary levels of 25-hydroxyvitamin D3 in growing piglets.

Forty-eight, cross-bred (GL×LW×P) piglets were used in a 42-day tolerance trial to assess the effects of feeding diets supplemented with vitamin D or increasing levels of 25-hydroxyvitamin D3 (25-OH-D3 ). Six-week-old piglets (24 castrate males, 24 females) were used. Two replicate groups of 6 piglets were randomized by weight and allocated to four dietary treatments. The control group (T1) was supplemented with 50μg vitamin D3 /kg feed. The experimental groups received 25-OH-D3 at the recommended dose (T2: 50μg/kg=1x), at 250μg/kg (T3: 5x) or at 500μg/kg (T4: 10x) respectively. Feed intake and daily weight gain were measured weekly, and the animals were examined by a veterinarian daily. After 42days, body mass, blood, urine, bone and tissue samples were analysed and a pathology examination conducted. Dietary treatments had no significant effect on final body mass or daily weight gain. The 25-OH-D3 plasma concentration in T1 was 17±3ng/ml (mean±SD) while the respective values of the experimental groups were significantly increased in T2, T3 and T4. Tissue concentrations of 25-OH-D3 were higher in liver and muscle for T3 and T4 and in skin for T4 than in T1. However, neither gross pathology nor histology, nor blood and urine characteristics, nor bone parameters were affected by dietary treatments. Weight of organs as well as dry matter, ash and calcium content of kidneys remained unaffected by dietary 25-OH-D3 intake. Furthermore, no changes were observed for general indicators of health. The results of this study demonstrated that feeding piglets with 25-OH-D3 at 5 or 10 times the recommended level had no adverse effects on any of the biological parameters measured. It was concluded that 25-OH-D3 can be regarded as a supplement with a very high safety margin when used at the recommended level.

Axon diameter and axonal transport: In vivo and in vitro effects of androgens

Testosterone is a sex hormone involved in brain maturation via multiple molecular mechanisms. Previous human studies described age-related changes in the overall volume and structural properties of white matter during male puberty. Based on this work, we have proposed that testosterone may induce a radial growth of the axon and, possibly, modulate axonal transport. In order to determine whether this is the case we have used two different experimental approaches. With electron microscopy, we have evaluated sex differences in the structural properties of axons in the corpus callosum (splenium) of young rats, and tested consequences of castration carried out after weaning. Then we examined in vitro the effect of the non-aromatizable androgen Mibolerone on the structure and bidirectional transport of wheat-germ agglutinin vesicles in the axons of cultured sympathetic neurons. With electron microscopy, we found robust sex differences in axonal diameter (males>females) and g ratio (males>females). Removal of endogenous testosterone by castration was associated with lower axon diameter and lower g ratio in castrated (vs. intact) males. In vitro, Mibolerone influenced the axonal transport in a time- and dose-dependent manner, and increased the axon caliber as compared with vehicle-treated neurons. These findings are consistent with the role of testosterone in shaping the axon by regulating its radial growth, as predicted by the initial human studies.

Sodium valproate effect on the structure of rat glandule thymus: Gender-related differences

Sodium valproate (VPA) was shown to inhibit cell growth mechanisms such as cell cycle arrest, proliferation suppression, increase of apoptosis. Many aspects of the contribution of the VPA pharmacological mechanisms and their significance in gender-related processes have not been investigated. In our study, we have tested hypothesis that the influence of VPA on thymus weight and structure might be gender-related. The thymus of Wistar rats of both genders aged 8 weeks was investigated in the following groups (n=6 each): controls, treated with VPA, castrated male and female treated with VPA, and the castrated control of both genders. The thymus weight, structural changes and area of cortical and medullar parts of the gland in slides stained with hematoxylin and eosin and immunohistochemically were assessed. A comparison of thymus weight of castrated male and of castrated VPA-treated male rats showed a significant thymus weight loss after VPA treatment (0.66±0.04g vs. 0.43±0.03g, p<0.05). The treatment with VPA caused an about 6-fold (0.39±0.12 vs. 0.07±0.03) increase of Hassall‘s corpuscles (HCs) numbers per 1mm2 in male and more than 4-fold increase (0.46±0.07 vs. 0.10±0.04) in female rats. In castrated males and females, the HCs number was also increased, but this increase was statistically significant only in male animals vs. controls (0.46±0.10 vs. 0.07±0.03, p<0.001 in males; 0.29±0.13 vs. 0.10±0.04, p>0.05 in females). When castrated male and female rats were treated with VPA, further increase of HC numbers was found. In our study, VPA has inhibited the proliferative capacity of thymocytes by diminishing the thymus weight and inducing a differentiation of thymic medullar epithelial cells into HCs. The diminishing of the gl. thymus weight under the influence of VPA was significant in castrated male rats. The number of HCs increased in animals of both genders under the influence of VPA. Gender differences in HCs development were noted in castrated animals.

Metastatic cholangiocellular carcinoma in Kankrej bullock

Sixteen years old castrated Kankrej male was found dead after short clinical illness. On necropsy, multiple yellow to yellowish white, umbilicated, well demarcated, firm nodules of 3 to 20 cm in size were found on liver, lung, adrenals, lymph nodes and thoracic wall. Histologically, neoplasm was composed of round to polygonal cells arranged in irregular mass, poorly formed ducts, supported by a moderate to dense collagenous fibrovascular stroma. Neoplasm was diagnosed as poorly differentiated cholangiocellular carcinoma with desmoplasia. Diagnosis was confirmed by positive cytokeratin 7/17 immunostaining.

Dorsomedial hypothalamic lesions counteract decreases in locomotor activity in male Syrian hamsters transferred from long to short day lengths.

The dorsomedial nucleus (DMN) of the hypothalamus has been implicated in seasonal control of reproduction. Syrian hamsters with DMN lesions, unlike control hamsters, do not undergo testicular regression after transfer from a long day length (14 h of light per day; LD) to a short day length (8 h of light per day; SD). SDs also markedly reduce hamster locomotor activity (LMA). To assess whether the DMN is a component of the neural circuitry that mediates seasonal variation in LMA, neurologically intact males (controls) and hamsters that had sustained lesions of the DMN (DMNx) were housed in an LD or SD photoperiod for 26 weeks. DMNx that prevented testicular regression counteracted decreases in LMA during 8 to10 weeks of SD treatment; steroid-independent effects of SDs did not override high levels of LMA in DMNx males. As in previous studies, testosterone (T) restoration increased LMA in LD but not SD castrated control males. In the present study, T also failed to increase LMA in SD-DMNx hamsters. The DMN is not necessary to maintain decreased responsiveness of locomotor activity systems to T in SDs, which presumably is mediated by other central nervous system androgen target tissues. Finally, DMNx did not interfere with the spontaneous increase in LMA exhibited by photorefractory hamsters after 26 weeks of SD treatment. We propose that DMN is an essential part of the substrate that mediates seasonal decreases in LMA as day length decreases but is not required to sustain decreased SD responsiveness to T or for development of refractoriness to SDs.

Sex-specific mechanism of social hierarchy in mice.

The establishment of social hierarchies is a naturally occurring, evolutionarily conserved phenomenon with a well-established impact on fitness and health. Investigations of complex social group dynamics may offer novel opportunities for translational studies of autism spectrum disorder. Here we describe a robust behavioral paradigm using an automated version of the tube test. Isogenic groups of male and female mice establish linear social hierarchies that remain highly stable for at least 14 days, the longest interval tested. Remarkably, however, their social strategy is sex-specific: females primarily utilize intrinsic attributes, whereas males are strongly influenced by prior social experience. Using both genetic and pharmacological manipulations, we identify testosterone as a critical sex-specific factor for determining which social strategy is used. Males inheriting a null mutation of the sex-determining region Y (Sry) gene used a similar social cognitive strategy as females. In contrast, females with transgenic expression of Sry utilized a typically male social strategy. Analogously, castration of males and testosterone supplementation of females yielded similar outcomes, with a reversal of their social cognitive strategy. Together, our results demonstrate a sex-specific mechanism underlying social hierarchy, in which both males and females retain the functional capacity to adapt their social strategy. More generally, we expect the automated tube test to provide an important complementary approach for both fundamental and translational studies of social behavior.

Abstract 249: Male Mice with XX Sex Chromosome Complement Exhibit Reduced Angiotensin II-Induced Hypertension and Atherosclerosis

Objective: Hypertension and atherosclerosis exhibit sexual dimorphism, partially ascribed to effects of sex hormones. However, recent studies suggest that sex chromosome complement may also contribute to sexual dimorphism of these diseases. The renin-angiotensin system has been suggested to contribute to sexual dimorphism of hypertension and atherosclerosis. However, the relative contribution of sex hormones, versus chromosomes, in the regulation of angiotensin II (AngII)-mediated responses is unknown. We hypothesized that the presence of an XX chromosome complement in male hyperlipidemic mice would reduce AngII-induced hypertension and atherosclerosis. Methods and Results: Male Ldlr-/- mice with an Sry mutation but with an Sry transgene on autosomes were bred to Ldlr-/- females to generate XY or XX males. Male XY or XX mice were segregated to sham-operated or orchiectomized (ORC) groups and fed a high fat diet (42% kcal from fat). Two weeks later, mice were infused with AngII (1,000 ng/kg/min) for 4 weeks. In the presence of sex hormones (sham groups), systolic blood pressure (SBP) was significantly lower in AngII-infused XX than XY males (XY, 136 ± 4; XX, 119 ± 4 mmHg, p=0.024). In XY males, ORC had no significant effect on SBP compared to sham (ORC XY, 129 ± 6 mmHg; p=0.48). However, following castration of XX males, SBP significantly increased (ORC XX 135 ± 3 mmHg; p =0.002). In XY males, ORC resulted in a significant increase in atherosclerotic lesion surface area in the aortic arch (sham, 19 ± 4; ORC, 32 ± 7%; p=0.04). In contrast, ORC had no significant effect on lesion surface area in XX males (sham, 17 ± 3; ORC, 15 ± 2%; p=0.53). Moreover, in the absence of sex hormones, lesion surface area was markedly increased in XY compared to XX males (XY, 32 ± 7; XX, 15 ± 2%; p=0.002). Conclusions: These results demonstrate that effects of testosterone to regulate AngII-induced hypertension and atherosclerosis are dependent on sex chromosome complement. In XY males, testosterone protects against AngII-induced atherosclerosis. In XX males, testosterone protects against AngII-induced hypertension. Moreover, there is pronounced effect of XY chromosome complement to promote AngII-induced atherosclerosis in males.

Intratesticular hypertonic sodium chloride solution treatment as a method of chemical castration in cattle

Castration of male calves is necessary for trading to facilitate handling and prevent reproduction. However, some methods of castration are traumatic and lead to economic losses because of infection and myiasis. The objective of the present study was to evaluate the efficiency of intratesticular injection (ITI) of hypertonic sodium chloride (NaCl; 20%) solution in male calf castration during the first weeks of life. Forty male calves were allocated to one of the following experimental groups: negative control—surgically castrated immediately after birth; positive control —intact males; G1—ITI from 1- to 5-day old; G2—ITI from 15- to 20-day old; and G3—ITI from 25- to 30-day old. Intratesticular injection induced coagulative necrosis of Leydig cells and seminiferous tubules leading to extensive fibrosis. Testosterone secretion and testicular development were severely impaired in 12-month-old animals from G1 and G2 groups (P < 0.05), in which no testicular structure and sperm cells were observed during breeding soundness evaluation. Rectal and scrotal temperatures were not affected by different procedures. In conclusion, ITI of hypertonic NaCl solution induces sterility and completely suppresses testosterone secretion when performed during the first 20 days of life.

An alternative to surgical desexing in ferrets

Veterinary RecordVolume 175, Issue 3 p. 64-65 Research An alternative to surgical desexing in ferrets Sandra Goericke-Pesch DVM, DrMedVet, DrHabil, DiplECAR, Corresponding Author Sandra Goericke-Pesch DVM, DrMedVet, DrHabil, DiplECAR sgp@sund.ku.dk...

Quantitative analysis of long-form aromatase mRNA in the male and female rat brain.

In vitro studies show that estrogens acutely modulate synaptic function in both sexes. These acute effects may be mediated in vivo by estrogens synthesized within the brain, which could fluctuate more rapidly than circulating estrogens. For this to be the case, brain regions that respond acutely to estrogens should be capable of synthesizing them. To investigate this question, we used quantitative real-time PCR to measure expression of mRNA for the estrogen-synthesizing enzyme, aromatase, in different brain regions of male and female rats. Importantly, because brain aromatase exists in two forms, a long form with aromatase activity and a short form with unknown function, we targeted a sequence found exclusively in long-form aromatase. With this approach, we found highest expression of aromatase mRNA in the amygdala followed closely by the bed nucleus of the stria terminalis (BNST) and preoptic area (POA); we found moderate levels of aromatase mRNA in the dorsal hippocampus and cingulate cortex; and aromatase mRNA was detectable in brainstem and cerebellum, but levels were very low. In the amygdala, gonadal/hormonal status regulated aromatase expression in both sexes; in the BNST and POA, castration of males down-regulated aromatase, whereas there was no effect of estradiol in ovariectomized females. In the dorsal hippocampus and cingulate cortex, there were no differences in aromatase levels between males and females or effects of gonadal/hormonal status. These findings demonstrate that long-form aromatase is expressed in brain regions that respond acutely to estrogens, such as the dorsal hippocampus, and that gonadal/hormonal regulation of aromatase differs among different brain regions.

Fatty acid profile of &amp;lt;i&amp;gt;m. longissimus dorsi&amp;lt;/i&amp;gt; of Mangalitsa and Moravka pig breeds

Abstract. The objective of this study was to determine the chemical composition and fatty acid content in m. longissimus dorsi (MLD) of two indigenous pig breeds (ML – Swallow-belly Mangalitsa and M – Moravka) reared in free range farm conditions and fed complete mixtures used for commercial meat pig genotypes. The body mass of ML and M pigs at slaughter was,on average, 107.14 and 107.61 kg, respectively. In MLD of M pigs, more total fat was measured compared to ML breed (6.96 % compared to 5.10 %, P&lt;0.05). Protein content in MLD of ML pigs was higher by +0.92 % (P&lt;0.01) compared to M pigs. Male castrates of M pigs had more fat compared to gilts of the same breed (8.64 compared to 5.29 %), and the 3.35 % difference between mean values was statistically significant (P&lt;0.05). The breed of pigs influenced the total saturated fatty acids (P=0.011) and mono-unsaturated fatty acid (P=0.003) contents, but not the content of polyunsaturated fatty acids (P=0.325). In the case of saturated fatty acids in the MLD of ML and M pigs, the most common were C16:0 (25.05 % and 25.53 %) and C18:0 (12.73 % and 14.40 %). The MLD of M pigs contained 1.67 % more stearic acid compared to ML pigs (P=0.004). Pigs of ML, compared to M pigs, had more C18:1cis-9 (+2.31 %), C16:1 (+0.49 %), C17:1 (+0.10 %) and less C20:1cis-11 (–0.25 %). The content of two essential fatty acids, C18:2n-6 and C18:3n-3, did not vary according to breed or sex of pigs (P&gt;0.05). The n-6/n-3 ratio was higher than optimal (18.7 for breed ML and 13.7 for M).

Evaluation des pratiques paysannes de conservation in situ du taurin Baoulé au Sud-Ouest du Burkina Faso

The study evaluated the small farmers' practices implemented by cattle breeders to ensure the conservation of the Baoulé breed. The study involved 52% of the 636 known producers from the 54 targeted villages, which constitute 7% of the total villages of the Poni and Noumbiel provinces in Burkina Faso. The transverse and retrospective survey was carried out and was combined with direct observation. The modalities of the frequencies of various actions and the coefficients that affected them were transformed into quantitative variables. Adhesion to a possible project of conservation, participation in farmers’ groups and other associations and schooling induce positive acts of conduct, health care and social activities for conservation but have a negative effect on reproduction (cross breeding). Membership of the Lobi ethnic group contributes to the conservation of Baoulé cattle. The possession of draught animals promotes the activities of conduct, management, health care and social activities that are protective but active management of reproduction does not contribute to conservation. Moreover, the possession of an exclusive herd of Baoulé cattle, the castration of males from other cattle breeds, the taking of individual decisions of management and the membership of Lobi ethnic group are all favourable to the conservation of Baoulé cattle. The positive total assessment of the practices implemented in the Lobi region of Burkina Faso shows the limited development of Baoulé cattle crossbreeding. The quantitative variables obtained by transformation constitute a new approach, making it possible to quantify the practices of conservation of the animal breeds in their natural environment (in situ).

Genetic diversity and population structure in remnant subpopulations of Nordestino horse breed

This study analyzed four remnant subpopu- lations of Nordestino horse breed to detect genetic structure and diversity through 14 microsatellite markers. Hair root follicles from a total of 393 horses were collected. There were 61 animals from Salitre Valley (JUAZ-BA) located at Bahia state, 89 from North and Central North ecoregions located at Piaui state (NCEN-PI), 185 animals from Sertao and Sertao do Sao Francisco ecoregions (SERT-PE) and 58 animals from Agrestina city (AGRE-PE) located at Pernambuco state. Genetic diversity, genetic differentiation and bottleneck effects were examined in the 4 remnant subpo- pulations of Nordestino horse breed. There was high allelic diversity and the F is value did not show evidence of a significant predominance of mating among relatives, probably because of crossbree- ding among populations. Recent bottleneck effects were not detected in the 4 subpopulations, but the IAM and TPM model did suggest a bottleneck effect. This may be a reflection of the decreased number of breeding animals caused by castration of males, mechanization processes and changes in life style in the rural areas. The bottleneck event was not enough to lead a genetic differentiation among the 4 remnant subpopulations of Nordestino horse. There was no evidence of genetic diffe- rentiation, so the 4 subpopulations formed one genetic group.

Castration of male mice prevents the progression of established angiotensin II-induced abdominal aortic aneurysms

Male sex is a nonmodifiable risk factor for abdominal aortic aneurysm (AAA) development. Similar to humans, male mice are more susceptible to angiotensin II (AngII)-induced AAAs than female mice. Previous studies demonstrated that castration of males markedly reduced the formation of AngII-induced AAAs. Progression of AAA size is associated with increased risk of aneurysm rupture. In this study, we hypothesized that castration of male mice would reduce the progression of established AngII-induced AAAs. Male apolipoprotein E-deficient mice were infused with AngII for 1 month to induce AAA formation. Aortic diameters were measured by ultrasound imaging, and mice were stratified into two groups that underwent a sham operation or castration. AngII infusions were continued for a further 2 months. Ultrasound imaging was used to quantify lumen diameters, and excised aortas were processed for quantification of AAA size, volume, and tissue characteristics. Sham-operated mice exhibited progressive dilation of suprarenal aortic lumen diameters during the continued AngII infusion. Aortic lumen diameters were significantly decreased in castrated mice (n = 17) compared with sham-operated mice (n = 15) at study end point (1.63 ± 0.04 vs 1.88 ± 0.05 mm; P < .05). However, maximal external AAA diameters were not significantly different between sham-operated and castrated mice. The vascular volume/lumen volume ratio of excised AAAs imaged by ultrasound was significantly increased by castration (9.5% ± 2.0%) vs sham operation (4.8% ± 0.9%; n = 11 per group; P < .05). Moreover, compared with the thin-walled AAAs of sham-operated mice, aneurysm sections from castrated mice exhibited increased smooth muscle α-actin and collagen. Removal of endogenous male hormones by castration selectively reduces aortic lumen expansion while not altering the external AAA dimensions. There are no therapeutics that slow the progression of abdominal aortic aneurysms (AAAs), and as the size of an AAA increases, so does the risk of rupture and death. Male sex is a nonmodifiable risk factor for AAA development, but whether male sex hormones have a similar effect on AAA progression is unclear. Removal of male sex hormones in an established mouse model of angiotensin II-induced AAAs resulted in reduced progressive lumen dilation while not altering external AAA dimensions. Therapies that limit androgen action may provide benefit against AAA progression. Alternatively, supplemental testosterone may be contraindicated in men diagnosed with an AAA.

Endoscopic assisted orchiectomy in Herman's tortoises (Testudo hermanni sp.).

Male tortoises in captivity are often aggressive against other males or females, in particular during mating season related to hormonal influences (testosterone). Castration in males is the treatment of choice in many vertebrate species. A novel technique of minimal invasive castration is presented for Herman's tortoises (Testudo hermanni). The procedure was performed in ten mature males. An endoscope (2.7 mm/30° angled) was inserted into a prefemoral incision on each side. The testicle was resected after ligation of the gubernaculum testis and the spermatic cord using hemoclips. Each testicle could be removed in approximately 20 minutes. Complications like hemorrhage or damage of adjacent tissue did not occur and all animals recovered uneventfully. Using the bilateral prefemoral entrance offers an alternative option for orchiectomy in Herman's tortoises without dissection of the shell. Thus complications like hemorrhage or impaired wound healing followed by sequestration of the bone flap are prevented. Because of the anatomical settings and the risk of tissue damage and time consumption, a unilateral approach is not recommended. Fasting the animals is necessary due to the voluminous gastrointestinal tract of this herbivorous tortoise and emptying the urinary bladder provides more space for manipulations in the coelomic cavity and prevents clipping and cutting of adjacent organs. The magnification via the endoscope is beneficial for orientation in the coelomic cavity, which is formed by the extremely convex carapace. Without this equipment it is challenging to visualize the dorsocaudally located gonads through the relatively small incision and the inserted instruments might block the view at the surgical field. Administration of hemoclips achieved a good hemostasis and the testicles could be resected without major blood loss. The described technique is a gentle method for resection of the testicles in this species and can be adapted to other European tortoise species of equal size.

Factors influencing the incidence of high rigor temperature in beef carcasses in Australia

Beef carcasses undergoing rapid pH fall while the loin muscle temperature is still high are described as heat-shortened, heat-toughened or ‘high rigor temperature’ carcasses, with subsequent negative effects on quality traits. The aim of the study was to quantify the occurrence of high rigor temperature in beef carcasses across Australia and to identify the causative factors. Data was collected over 4–5 days at each of seven beef processing plants from 1512 beef carcasses. The beef carcasses were from both grass- and grain-fed cattle ranging in days on grain feeding from 0 (grass-fed) to 350 days and the category of cattle ranged from veal to ox and cow. Data collected on the day of slaughter included the duration of electrical inputs at the immobiliser, electrical stimulation and hide puller, longissimus muscle pH and temperature decline, hot carcass weight and P8 fat depth. At grading, ultimate pH, eye muscle area, wetness of the loin surface and colour score were also collected. The temperature at pH 6 was calculated and if it was &gt;35°C, the carcass was defined as ‘high rigor temperature’. Modelling of the data was conducted using GLMM and REML. The occurrence of high rigor temperature across all seven beef processing plants was 74.6% ranging from 56 to 94% between beef processing plants. Increasing days in the feedlot and heavier carcass weights were highly correlated and both caused an increase in the predicted temperature at pH 6 and in the % high rigor temperature (P &lt; 0.05 for both). Longer duration of electrical inputs at the hide puller, fatter grass-fed cattle and fatter male (castrate) carcasses had a higher temperature at pH 6 and higher % high rigor temperature. Modelling showed that if the time to reach pH 6 in the longissimus muscle was 65 v. 105 min, the % high rigor temperature carcasses reduced from 98 to 19% in grain-fed cattle and 93 to 7% in grass-fed cattle. Higher plasma insulin levels at slaughter were associated with a higher temperature at pH 6 (rigor temperature) (P &lt; 0.001). In conclusion, in order to reduce the incidence of high rigor temperature in grain-fed beef carcasses, methods for identifying high rigor temperature carcasses will be required and while some management strategies can be implemented now, others require further research.

Influence of the brain sexual differentiation process on despair and antidepressant-like effect of fluoxetine in the rat forced swim test

Sex differences exist in the depressive disorder prevalence and response to treatment. Several studies suggest that females respond better than males to the action of selective serotonin reuptake inhibitors (SSRIs), suggesting that gonadal hormones modulate mood and the response to these drugs. Sexual steroid hormones exert organizational actions (perennial and on early development) and activational effects (transient and on differentiated tissues). The aim of this study was to analyze sex differences in the forced swim test (FST) in animals without treatment and after fluoxetine (FLX, 0, 2.5, 5.0 and 10.0mg/kg). Initially, we compared male and female adult rats under control conditions or after altering their sexual differentiation process (at day 5 postnatally, PN, 60μg of testosterone propionate to females and male castration to induce or preclude masculinization, respectively). To further analyze if the sex differences depend on organizational or activational steroid hormone action we tested the same animals before and after adult gonadectomy. To prevent variations depending upon the estrous cycle, control and masculinized females were tested in estrus. Control females showed lower immobility and required lower doses of FLX (5mg/kg), to show an antidepressant-like effect, than males (10mg/kg), even after adult gonadectomy. In control males adult orchidectomy prevented FLX’s action. Neonatally masculinized females exhibited analogous levels of immobility than control ones; before ovariectomy they responded to FLX similar to controls, but after the surgery they did not respond to fluoxetine. Neonatally orchidectomized males exhibited similar immobility values and response to FLX than control females. The findings suggest that the sex difference in despair depends on the hormones organizational effects and, in males, the response to FLX relies on organizational and activational actions.