Intact Adult Males Research Articles

Assessing welfare risks in unowned unsocialised domestic cats in Denmark based on associations with low body condition score

BackgroundPopulations of unowned unsocialised cats are present worldwide. Generally, there is concern about their welfare. Low body condition score (BCS) is a potentially relevant indicator that is relatively easy to assess: emaciated cats are likely to have welfare problems while thin cats may be at risk of becoming emaciated. The objective of this study was to assess the association of low BSC with a selection of factors relating to the host, disease, and infection in unowned unsocialised domestic cats. We necropsied 598 euthanised unowned unsocialised cats from Denmark. We recorded each cat’s age-group, sex, and neuter status, together with its pregnancy status, the season and location of trapping, as well as gross lesions at necropsy. We also tested for feline immunodeficiency virus and feline leukaemia virus, recorded presence of ectoparasites, and a subsample of the cats were also tested for endoparasites. Cats with no or sparse adipose deposits were categorised as having low BCS, and logistic regression was used to determine the factors associated with low BCS.ResultsOf the cats, 11.4% had low BCS. Season, age-group and sex were associated with low BCS and confounded potential associations with other variables. Intact adult males and females in spring and early summer were at highest risk of low BCS. When these factors were taken into account, cats with biting lice had 2.8 (95% confidence interval (CI) 1.4–5.4) times higher odds of low BCS, and cats with gastro-intestinal findings (i.e., enlarged mesenteric lymph nodes, abdominal hernia, diarrhoea, obstructive foreign bodies, or diaphragmatic hernia) had 50 (95% CI 10–417) times higher odds of low BCS, than cats with no such findings. Cats with low BCS were primarily adult intact cats with tooth lesions and skin lesions, ear mite infection, and positive test result for feline immunodeficiency virus.ConclusionsThe results highlight associations that can be used to define a risk profile: low BCS, notably in summer-autumn, in an unowned unsocialised cat was associated with underlying, less visible problems. Thus, low BCS can be more than a step towards being emaciated; it can also be an indicator of other underlying welfare problems.

Effect of adult male sterilization on the behavior and social associations of a feral polygynous ungulate: the horse

Castration is commonly used to control the behavior of companion animals and livestock, yet there have been few longitudinal studies of its effects. Despite the ubiquity of this surgery in ridden horses, the effects of castration (termed gelding in horses) have rarely been examined in a reproductive population. We tested effects of gelding on maintenance and social behaviors of individuals pre- and post-gelding, and in comparison to intact control adult males (2 to >16 years old) in both harem and bachelor status, we then tested how gelding affected association with mares (i.e., maintenance of a harem group) compared to intact controls, and any effects on bachelor social associations. We further explored any effects on foaling rate to assess potential impacts on population growth rate. We conducted this study over four years (2017–2020) at two Herd Management Areas (HMAs) in western Utah, USA: Conger and Frisco. We conducted demographic observations year round at both HMAs to record survival and foaling rate. We additionally recorded behavioral observations at Conger HMA. In December 2017, 27 adult males from Conger (42% of adult males in the population) were gelded and returned to the range with their social groups. Due to pre-treatment observations we were able to compare stallions of known status pre- and post-treatment (harem or bachelor), as well as gelded and intact males. We had no morbidity or mortality related to the gelding surgery and all males maintained good body condition throughout the study. There was no effect of gelding on maintenance behaviors (feeding, moving, and standing). There was no effect of gelding on frequency of agonistic behavior, and a non-significant tendency for less reproductive behavior in geldings; geldings showed more affiliative and less marking behavior. Age class and/or social status were better predictors of behavior than gelding. Over time fewer geldings maintained a harem, and their harem size declined during the study. Horses that were bachelors when gelded tended to remain as bachelors, whereas intact bachelors of the same cohort mostly attained a harem. Foaling rate at Conger was reduced in the year following treatment, but then returned to pre-treatment levels. From a welfare perspective gelding is safe to use in feral horses and has minimal effects on horse behavior and social interactions in a reproductive herd. Effectiveness for population growth control would likely require a larger proportion of males in the population to be castrated for longer-term effects on foaling rate.

The effect of pyriproxyfen on the concentration of circulating metabolic fuel molecules and chemical elements in the hemolymph of Acraea horta L. (Lepidoptera: Nymphalidae): A quantitative analysis

Many pollinating insects expand their niche to adjacent agricultural areas and are, therefore, exposed to chemical insecticides. Acraea horta L. (Lepidoptera: Nymphalidae) is a pollinator butterfly widely distributed in the Southern African region. The objectives of this work were to evaluate carbohydrate, lipid and chemical elements in the hemolymph of A. horta exposed to pyriproxyfen, a juvenile hormone analog (JHA). Last instar larvae (L6: day 1 or day 2) were topically exposed to an aqueous solution of pyriproxyfen (100 μg of the active ingredient per insect) or to diluent (control group). Hemolymph was collected after adult eclosion to determine total carbohydrate and lipid concentrations: in the control group lipids were present in lower concentrations than carbohydrates and there was no significant difference in metabolite levels between sexes; a similar pattern with similar levels were measured in the treated group, except that lipid concentrations in treated males were lower, and carbohydrate concentrations in treated females were lower than the control values. Morphologically intact adult males from treated larvae were subjected to free flight; their hemolymph carbohydrate levels were significantly reduced and did not recover to starting levels in a 30 min rest period following the exhaustive flight episode. To assess the effect of pyriproxyfen on a different stage of development, 48 h old butterflies were treated in the same way as described for the L6 larvae above; hemolymph samples were taken 48 h later for metabolite measurements and for quantification of chemical elements: carbohydrate levels decreased significantly after pyriproxyfen exposure, while lipid levels increased; inorganic elements measured in untreated adults were more abundant in females, with a general decrease in concentration following pyriproxyfen exposure, except for an increase in Fe levels in males and Cl levels in females. The quantitative changes measured in A. horta hemolymph via biochemical and chemical element analyses may indicate distinct physiological interferences beyond the main mode of action of pyriproxyfen on JH activity. In conclusion, the use and quantification of pyriproxyfen should be carefully evaluated prior to application in areas where A. horta and other pollinator species occur.

Low-molecular weight components of cow colostrum regulate bone marrow functions by modelling the redox-system of the organism

Colostrum is rich in various biologically active compounds such as immunotropic ones. Low molecular weight components were isolated from cow colostrum components (with a molecular weight of not more than 45 kDa). Their influence was investigated on intact Wistar Rattus norvegicus adult males in concentrations of 0.01, 0.1, 1.0 and 5.0 g/100 g of body weight. We determined content of lipid hydroperoxides and activity of serum glutathione peroxidase in blood serum, parameters of the bone marrow cells’ (BMCs) behaviour in the in vitro system (proliferation ability, morphologically identifiable and unidentifiable type of cells, lifespan of eosinophils). Morphological identifiable cells were stab neutrophils, segmented neutrophils, metamyelocytes, myelocytes, lymphocytes, basophils, neutrophils, eosinophils, monocytes. The low doses of colostrum components (0.01–0.10 g/100 g of body weight) did not affect the ratio of morphologically identifiable/unidentifiable cells. Administration of colostrum components at low doses (0.01 g/100 g of weight) increased the ability of BMCs to proliferate in the in vitro system. A super-large dose of colostrum components (5 g/100 g of body weight) was accompanied by a further loss of capacity for proliferation and cell death. Moreover, large doses of colostrum components resulted in change of balance to prooxidants (oxidants). The role of redox – system in BMCs functions was discussed. Large doses of colostrum components (1–5 g/100 g of body weight) were accompanied by a change of pro-antioxidant system balance. Only eosinophils were determined after administration of colostrum components in a large dose. It should be noted that the lifetime of eosinophils which developed under influence of colostrum components was greater than that of eosinophils obtained from control animals.

Androgen action at the target musculature regulates brain‐derived neurotrophic factor protein in the spinal nucleus of the bulbocavernosus

We have previously demonstrated that brain-derived neurotrophic factor (BDNF) interacts with testosterone to regulate dendritic morphology of motoneurons in the highly androgen-sensitive spinal nucleus of the bulbocavernosus (SNB). Additionally, in adult male rats testosterone regulates BDNF in SNB motoneurons and its target muscle, the bulbocavernosus (BC). Because BDNF is retrogradely transported from skeletal muscles to spinal motoneurons, we hypothesized that testosterone could regulate BDNF in SNB motoneurons by acting locally at the BC muscle. To test this hypothesis, we restricted androgen manipulation to the SNB target musculature. After castration, BDNF immunolabeling in SNB motoneurons was maintained at levels similar to those of gonadally intact males by delivering testosterone treatment directly to the BC muscle. When the same implant was placed interscapularly in castrated males it was ineffective in supporting BDNF immunolabeling in SNB motoneurons. Furthermore, BDNF immunolabeling in gonadally intact adult males given the androgen receptor blocker hydroxyflutamide delivered directly to the BC muscle was decreased compared with that of gonadally intact animals that had the same hydroxyflutamide implant placed interscapularly, or when compared with castrated animals that had testosterone implants at the muscle. These results demonstrate that the BC musculature is a critical site of action for the androgenic regulation of BDNF in SNB motoneurons and that it is both necessary and sufficient for this action. Furthermore, the local action of androgens at the BC muscle in regulating BDNF provides a possible mechanism underlying the interactive effects of testosterone and BDNF on motoneuron morphology. © 2013 Wiley Periodicals, Inc. Develop Neurobiol 73: 587-598, 2013.

Effect of estradiol benzoate on the pituitary-gonadal axis in the intact male rat.

Adult male rats were treated with 50 microgram of estradiol benzoate daily for 28 days. The sex organs and pituitary weights showed changes classically associated with estrogen treatment. Both plasma and testicular testosterone levels diminished to almost trace level 24 hours after the first estrogen injection and remained at that level throughout the experimental period. The pituitary LH levels and concentration showed a progressive decline; however, the plasma LH levels remained unchanged throught the experimental period. These findings suggest that in intact adult males, estrogen affects testicular testosterone production directly. These observation suggests the necessity for reevaluation of the current concepts concerned with testis-pituitary feedback mechanisms.

Seroprevalence of feline leukemia virus and feline immunodeficiency virus infection among cats in North America and risk factors for seropositivity

To determine seroprevalence of FeLV and FIV infection among cats in North America and risk factors for seropositivity. Prospective cross-sectional survey. 18,038 cats tested at 345 veterinary clinics (n=9,970) and 145 animal shelters (8,068) between August and November 2004. Cats were tested with a point-of-care ELISA for FeLV antigen and FIV antibody. A multivariable random effects logistic regression model was used to identify risk factors significantly associated with seropositivity while accounting for clinic-to-clinic (or shelter) variability. 409 (2.3%) cats were seropositive for FeLV antigen, and 446 (2.5%) cats were seropositive for FIV antibody; 58 (0.3%) cats were seropositive for infection with both viruses. Multivariable analysis indicated that age, sex, health status, and cat lifestyle and source were significantly associated with risk of seropositivity, with adults more likely to be seropositive than juveniles (adjusted odds ratios [ORs], 2.5 and 2.05 for FeLV and FIV seropositivity, respectively), sexually intact adult males more likely to be seropositive than sexually intact adult females (adjusted ORs, 2.4 and 4.66), and outdoor cats that were sick at the time of testing more likely to be seropositive than healthy indoor cats (adjusted ORs, 8.89 and 11.3). Results suggest that certain characteristics, such as age, sex, health status, and lifestyle, are associated with risk of FeLV and FIV seropositivity among cats in North America. However, cats in all categories were found to be at risk for infection, and current guidelines to test all cats at the time of acquisition and again during illness should be followed.

Testosterone Regulates Androgen Receptor Immunoreactivity in the Copulatory, but not Courtship, Neuromuscular System in Adult Male Green Anoles

Androgens regulate the expression of male reproductive behaviour in diverse vertebrate species, often acting on androgen receptors (AR) to induce structural or functional changes in the nervous system and periphery. Male green anoles possess two sexually dimorphic neuromuscular systems, one controlling throat fan (dewlap) extension, which occurs during courtship, and the other mediating copulatory organ function. Although androgens are required for behavioural activation in both systems, testosterone has differential effects on the neuromuscular morphology. It increases the size of copulatory muscle fibres during the breeding season, but significant effects on dewlap muscle fibre size and motoneurone soma size in either system have not been detected. Corresponding to the lack of testosterone-induced morphological effects in the courtship system, relatively low levels of AR are expressed in the associated motoneurones. The present experiment had two goals, aiming to determine whether: (i) the other courtship and copulatory neuromuscular tissues express AR and (ii) testosterone and/or seasonal environmental changes regulate AR expression. The percentage of AR+ nuclei was evaluated in both the breeding and nonbreeding seasons in gonadally intact adult males (Experiment 1) and in castrated males treated with either testosterone or vehicle (Experiment 2). AR was extensively expressed in the dewlap and copulatory muscles, and in a high percentage of the copulatory motoneurones, but immunoreactivity did not vary across season. Testosterone increased the percentage of AR+ nuclei in the copulatory muscles of both breeding and nonbreeding males but not in the dewlap muscle or copulatory motoneurones. Finally, the target structures for both systems (cartilages and hemipenes) expressed AR in all animals. Therefore, the effects of testosterone on AR immunoreactivity suggest that up-regulation of the receptors may be important for morphological change. However, because all structures investigated in the present experiment expressed AR, the data also indicate that the receptors are involved with other functions.

Antiandrogenic effects in short-term in vivo studies of the fungicide fenarimol

The fungicide fenarimol has estrogenic and antiandrogenic activity and inhibits aromatase activity in vitro. We tested, whether fenarimol had antiandrogenic effects in vivo. In a Hershberger assay, fenarimol given orally to castrated testosterone-treated male rats caused markedly reduced weights of ventral prostate, seminal vesicles, musc. levator ani/bulbocavernosus, and bulbourethral glands. Qualitatively similar, but weaker, effects were also evident in intact fenarimol-exposed young adult males, except that prostates were not significantly affected. Changes in androgen-regulated gene expression were determined by real-time RT-PCR in ventral prostates and fenarimol caused a pronounced decrease of prostate binding protein C3 (PBP C3), ornithin decarboxylase (ODC), and insulin-like-growth factor 1 (IGF-1) mRNA levels. The antiandogenic drug flutamide, included as a positive control, caused down-regulation of PBP C3 mRNA and up-regulation of TRPM-2 mRNA levels. Serum T4 levels were reduced after fenarimol treatment and a tendency towards increased LH levels was seen. However, no effects on testosterone levels or testosterone production ex vivo could be revealed. Taken together these results indicate that fenarimol acts as an antiandrogen in vivo having effects qualitatively comparable to those of flutamide on organ level, whereas differential effects on gene expression were observed. In an additional Hershberger test, the effects of fenarimol were compared to those of estradiol benzoate, prochloraz and the aromatase inhibitor fadrozole. The data indicate a similar mode of action of fenarimol and prochloraz in the males, whereas no indications were found that the estrogenic or aromatase inhibitory properties had important impact on the effects observed in the males. Thus, it is suggested that fenarimol mediates its antiandrogenic effects at least partly via antagonism of androgen receptors.

Using learned calls to study sensory-motor integration in songbirds.

Communicating songbirds produce calls as well as song and some of these are learned. One of these-the long call in zebra finches-is used by both sexes in similar behavioral contexts, but is learned in males and not in females. The male long call includes learned spectral and temporal features. In several studies, the learned long call has been used as a tool to study sensory-motor integration and vocal learning in a way that complements the use of song. Lesion studies showed that production of the male-typical call features requires an intact nucleus RA, the sexually dimorphic source of the telencephalic projection to brainstem vocal effectors. Behavioral studies that quantified zebra finch calling in response to long call playbacks showed that intact adult males have a categorical preference, absent in females, for the long calls of females over those of males. By using synthetic call stimuli, it was found that males use both spectral and temporal information to classify long call stimuli by gender, but that females use only temporal information. In juvenile males, the emergence of categorical preference occurs during the same period when RA matures anatomically (40-50 days) and the first male-typical vocalizations are produced. Adult males with RA lesions lost the categorical preference for female long calls, suggesting that RA could also play a role in long call discrimination. Preliminary analysis of recordings from neurons in NCM-a telencephalic auditory area (see Mello and colleagues, this volume)-suggests a pattern of responses to the spectral features of synthetic call stimuli that parallels the behavioral responses they elicit.

Effect of prenatal stress and gonadal hormone condition on depressive behaviors of female and male rats

Whether prenatal stress (PNS) and gonadal hormones may influence depressive behavior of rats in the forced swim test was investigated. In Experiment I, adult diestrous female rats had increased immobility, which is indicative of depression, but did not show any significant difference in the duration of struggling compared to intact adult males. In Experiment 2, the behavior of adult intact, castrated, or castrated dihydrotestosterone (DHT)- or estrogen (E 2)-replaced offspring of dams that were restrained under lights for 45 min on gestational day 18 (PNS) or were not subjected to gestational stress (non-PNS, control condition) were compared. There were no effects of PNS, but DHT and E 2 produced anti-depressant effects on behavior of male rats. Castration decreased struggling and increased immobility compared to intact rats. DHT or E 2 replacement was able to partially reinstate struggling and immobility behavior but not to levels of intact males. In Experiment 3, behavior of PNS or control rats that were in proestrus or were ovariectomized and DHT, E 2, or vehicle-replaced were compared. Ovariectomy decreased struggling and increased immobility compared to that of proestrous rats. E 2 or DHT to control females increased anti-depressant struggling behavior compared to ovariectomized control or PNS rats administered vehicle, which demonstrated greater duration of struggling than did E 2-primed, PNS rats. E 2 or DHT administration decreased immobility of PNS and control females. These findings suggest that E 2 and DHT have some anti-depressant effects but that modest PNS may alter E 2's ability to alleviate some depressive behavior in female, but not male rats.

Pheromones Elicit Equivalent Levels of Fos-Immunoreactivity in Prepubertal and Adult Male Syrian Hamsters

Male reproductive behavior in the Syrian hamster is dependent on both pheromones from the female and the presence of gonadal steroid hormones. The pheromones are contained within female hamster vaginal secretions (FHVS) and stimulate anogenital investigation and mounting by the male. Administration of testosterone to castrated male hamsters facilitates anogenital investigation, mounts, and intromissions in adults, but elicits only anogenital investigation in prepubertal males. One hypothesis for why the full complement of reproductive behaviors is not activated by testosterone in prepubertal males is that the neural processing of pheromonal cues encountered during anogenital investigation is different in juveniles and adults. In the present experiment, we investigated the influence of sexual maturity on Fos expression in response to FHVS in the male Syrian hamster. We predicted a greater increase in Fos-immunoreactivity after exposure to FHVS within the neural circuit mediating male reproductive behaviors in adult compared to prepubertal males. Intact adult and prepubertal males were exposed to either a clean cotton swab or a swab containing FHVS. We found that, compared to animals exposed to a clean cotton swab, both prepubertal and adult males exposed to FHVS have a greater amount of Fos-immunoreactivity within several brain nuclei comprising the neural circuit mediating male reproductive behavior. Furthermore, this Fos response was equivalent in the two age groups. These results suggest that the inability of the prepubertal male hamster to perform the full repertoire of male reproductive behaviors is not due to a lack of a neuronal activation in response to the pheromonal cues present in FHVS.

Interfemale aggression in adult bank voles (Clethrionomys glareolus)

Agonistic interaction may play a large role in shaping the social structure and spatial distribution of rodents such as Clethrionomys glareolus. Aggressive and non-aggressive behaviors of adult bank vole females were investigated with a home cage test during 10 min sessions. The number of attacks was significantly higher in virgin females kept with intact adult males than in singly reared females or those exposed to male urine. Bulbectomy of the tested females completely inhibited the male stimulating effect. This indicates that males influence the behavior of females by activating their olfactory systems. Aggressive behavior in pregnant or lactating females, which is linked to maternal behavior, was also tested. Female bank voles between 11 and 17 days of pregnancy or lactating at 3–4 days or 9–10 days attacked their partners significantly more frequently than virgins did. Females that had direct contact with males, even if they were not fertilized, appeared to be more successful in same-sex competition. Aggr. Behav. 24:53–61, 1998. © 1998 Wiley-Liss, Inc.

Androgen receptor-like immunoreactivity in the Brazilian opossum brain and pituitary: distribution and effects of castration and testosterone replacement in the adult male

Androgens are involved in a variety of centrally mediated functions after binding to their intracellular receptors. In the present report, we have employed the androgen receptor antibody, PG-21, and indirect immunuhistochemistry to examine the distribution of cells containing androgen receptor-like immunoreactivity (AR-IR) in the intact adult male Brazilian opossum brain and pituitary. Additional adult males were castrated to examine the effects of withdrawal of circulating androgens and testosterone replacement on AR-IR. Immunoblots and immunohistochemical controls demonstrated that the androgen receptor in the opossum brain and peripheral tissues are of a similar molecular mass as to has been reported for the rat. Cells containing AR-IR were widely distributed throughout the brain of intact adult males. The highest number of immunoreactive cells were present in the dorsal and ventral nuclei of the lateral septum, medial division of the bed nucleus of the stria terminalis, medial preoptic area, median preoptic nucleus, nucleus of the lateral olfactory tubercle, central amygdaloid nucleus, anterior cortical amygdaloid nucleus, posterior amygdaloid nucleus, subiculum, ventromedial hypothalamic nucleus, arcuate-median eminence region, and ventral premammillary nucleus. The anterior pituitary gland also contained a high number of cells containing AR-IR. The general distribution of AR-IR both in the brain and anterior pituitary gland resembled that reported for other mammalian species. Castration of the adult males four days prior to perfusion eliminated androgen receptor immunostaining throughout the brain except for a few lightly immunostained cells in the ventral nucleus of the lateral septum and stria terminalis. Androgen receptor immunostaining was decreased in the anterior pituitary gland following castration and became cytoplasmic. Testosterone administration 2 h before perfusion restored AR-IR both in the brain and anterior pituitary gland. These data suggested that immunohistochemscal detection of bound (nuclear) androgen receptors as seen with PG-21 antibody in the brain and anterior pituitary gland of the opossum is dependent upon circulating androgens. Further, the wide distribution and similarity in localization of androgen receptors in the opossum brain and anterior pituitary gland to that of other species suggests that androgen receptors might be involved in similar functions in the opossum as has been reported for other species.

Sexual dimorphism and sex steroid modulation of glial fibrillary acidic protein messenger RNA and immunoreactivity levels in the rat hypothalamus

By using the techniques of in situ hybridization histochemistry and immunocytochemistry, we have found that both glial fibrillary acidic protein messenger RNA levels and glial fibrillary acidic protein immunoreactive surface density in the arcuate nucleus and median eminence are modulated by both the neonatal and adult sex steroid environments. No effect was seen on the number of immunoreactive glia. Intact adult males had significantly higher glial fibrillary acidic protein messenger RNA levels and glial fibrillary acidic protein immunoreactive surface density than females. Both adult and neonatal castration of male animals significantly reduced glial fibrillary acidic protein messenger RNA levels and glial fibrillary acidic protein immunoreactive surface density. Neonatal and adult testosterone treatment increased both of these parameters in both sexes; however, there was no additive effect of the steroid treatments. Glial cells are involved in the proliferation, survival, migration and maturation of neurons, as well as in the modulation of synaptic connectivity, and therefore it follows that hormonal modulation of glia may mediate some of the known steroid effects on neurons. The data reported here show that astroglia are significantly influenced by both the neonatal and adult sex steroid environments and suggest that some of the steroid effects on neurons during both of these developmental periods may be mediated, at least in part, through modulation of glial cells.

Sexual Dimorphism of Urine Angiotensinogen Excretion in the Rat

To determine the source of angiotensinogen excreted in urine, urine angiotensinogen was measured in male and female rats during growth. Angiotensinogen in 24-hr urine, measured by direct radioimmunoassay with antibody against rat angiotensinogen, increased fourfold in males between the ages of 5 and 7 weeks, whereas no significant changes were observed in females or castrated males. Plasma levels of angiotensinogen, in contrast, showed no significant differences between these groups at any age. Castration of adult males caused a significant reduction of urinary angiotensinogen after 4 weeks. Consecutive s.c. administration of 17 alpha-methyltestosterone for 3 weeks in castrated males resulted in a threefold increase in the urinary excretion of angiotensinogen, as well as a twofold increase in the renal expression of angiotensinogen messenger RNA (mRNA). Renal levels of angiotensinogen mRNA in intact adult males were about threefold higher than those in females and castrated males, whereas there were no significant differences in hepatic angiotensinogen mRNA between these animals. These results suggest that the sexual differences in the urinary excretion of angiotensinogen are primarily due to the androgen-dependent dimorphic expression of angiotensinogen mRNA in the kidney; thus, levels of angiotensinogen in urine might reflect intrarenal production.

Sexual and aggressive behaviour of adult male marmosets ( Callithrix jacchus) castrated neonatally, prepubertally, or in adulthood

During early postnatal development, males of some primate species exhibit higher levels of plasma testosterone than females. The possible significance of this for behavioural development was examined in male marmosets castrated neonatally (NC), prepubertally (PC), or in adulthood (AC) and reared in their natal groups. Age-matched intact (AI) adult males served as controls. All males were removed from their natal groups as adults for pair testing with unfamiliar conspecific males and females. NC males did not mount, but were frequently aggressive during tests with females. NC males also elicited aggression from females but rarely from intact males. PC and AC males attempted copulation during the majority of tests with females; less aggression occurred but more so in tests with PC males than between females and AC males. Aggression between PC or AC males and intact males was much more frequent than when NC males met intacts in paired encounters. Results show that secretion of testicular hormones during infancy in male marmosets has important effects upon the development of sexual and aggressive behaviour. Castration in infancy has measurably different effects upon behavioural development than castration performed later in life (prepubertally or in adulthood).

Effects of Testosterone Propionate upon the Sexual and Aggressive Behavior of Adult Male Marmosets ( Callithrix jacchus) Castrated as Neonates

In New World monkeys of the family Callitrichidae (marmosets and tamarins), females frequently give birth to dizygotic twins. Twins share a placental circulation throughout fetal development and are hemopoietic chimeras. Despite this, there is no masculinization (freemartinism) in females which develop next to a male co-twin. It has been suggested that the organizing effects of testicular androgen upon sexual differentiation of the brain occur mainly during early postnatal development in male callitrichids, rather than in utero. However, this report demonstrates activation of masculine copulatory behavior by testosterone propionate (TP) administered to adult male marmosets ( N = 8) which were castrated in infancy (between Days 1-7). Effects of neonatal castration upon aggressive behavior during pair tests with females (high frequencies of aggression) anti intact adult males (low frequencies of aggression) were also reversed by TP treatment in adulthood. While early postnatal androgen secretion plays an important role in behavioral development in marmosets, it appears that a substantial degree of neural sexual differentiation occurs in utero in males of this callitrichid species.

Observations on effects of neonatal castration upon sexual and aggressive behavior in the male common marmoset (Callithrix jacchus).

The behavior of eight adult male marmosets that were bilaterally castrated during neonatal life (postnatal days 1-7), a single unilaterally castrated male, and eight age-matched intact adult males was observed during encounter tests with unfamiliar conspecifics. When neonatally castrated (NC) males encountered ovariectomized, estradiol-treated females, both partners were intensely aggressive and 66% of tests were terminated to avoid injuries. No mounts occurred, and females exhibited little or no sexual initiating behavior (proceptivity) towards NC males. By contrast, encounters between NC males and intact adult males were characterized by low levels of aggression and no tests were terminated. Intact males frequently mounted NC males. However, NC males initiated only 4% of these mounts by intact males and they refused or terminated 67% of mount attempts and mounts by intact males. The age-matched intact adult males provided data which differed markedly from those obtained using NC males. The intact males were highly aggressive during encounters with other intact males, whereas they mounted and ejaculated when paired with females. The single male which had been unilaterally castrated in infancy provided similar results to the intact males. These experiments indicate that neonatal castration has profound effects upon the development of sexual and aggressive behavior in male marmosets. However, the stimulus qualities as well as the behavior of males are altered by neonatal castration, so that unfamiliar conspecifics react towards them as females during paired encounters. This finding complicates the interpretation of effects of neonatal castration upon development of sexually dimorphic behavioral patterns in male marmosets. Behavioral effects of castration later in postnatal development romain to be determined. © 1993 Wiley-Liss, Inc.

Cadmium induction of renal and hepatic ornithine decarboxylase activity in the rat: Effects of sex hormones and involvement of the renin-angiotensin system

We investigated the effect of sex hormones on the sex-dependent response of rat kidney ornithine decarboyxlase (ODC) activity to cadmium (Cd) administration and the involvement of the renin-angiotensin system in mediating stimulation of the liver enzyme by the metal. The response of renal ODC to Cd, which occurs in intact adult males but not in females, is also detectable in prepubertal and castrated males. Upon treatment with 17β-estradiol, the basal levels of enzyme activity in intact or castrated adult males were enhanced and Cd administration failed to increase them further. In adult females the kidney enzyme became responsive after ovariectomy. Also, in prepubertal females renal ODC was induced by Cd, and this was prevented by treatment with 17β-estradiol. Under the same conditions, changes in the levels of Cd accumulation within the kidney, that might account for variations in the response of ODC activity, did not occur. Cd caused an increase in renin activity starting minutes after its injection. Captopril, which specifically inhibits the conversion of angiotensin I to angiotensin II, prevented completely the induction of liver ODC by this metal; stimulation of the enzyme by Co was not affected by the drug. A similar inhibitory effect was exerted by propranolol. Adrenalectomy had no influence on the response of hepatic ODC to Cd; the decarboxylase was unaffected by aldosterone administration. It is suggested that Cd may induce liver ODC through the increase in angiotensin II following stimulation of renin by the metal.