Seasonal variations in serum concentrations of testosterone, testicular volume and neck circumference of fallow deer (Dama dama) kept ex situ in a tropical region.

The fallow deer (Dama dama) is a species of Cervidae commonly kept in captivity, either in commercial farms or in zoos. The reproductive seasonality of this species is well known in the northern hemisphere, where photoperiod is a decisive factor in androgenic activity and, consequently, in the development of secondary sexual characteristics among male adults. The maintenance of this species in tropical regions has been successful, but there are no studies that demonstrate the maintenance of reproductive seasonality under these climatic conditions, which was the objective of the present study. To do so, the present investigation involved 27 fallow deer (D. dama) specimens, of which 14 were adults and 13 prepubescent (<8 months) individuals, all assessed during and outside (December-February) the reproductive season (June-August). The serum concentrations of testosterone, testicular volume, and neck circumference were analyzed among all animals during both seasons. The reproductive season was marked by expressive hormonal concentrations, increasing neck circumference and testicular volume, differing significantly between adults and prepubescent individuals outside the season. Positive correlations were observed among all analyzed variables: mean testicular volume and neck circumference (r = 0.92, p < 0.0001), testicular volume and testosterone concentrations (r = 0.79, p < 0.0001) and between neck circumference and testosterone concentrations (r = 0.67, p < 0.0001). Given the results found, the conclusion is that even under tropical climate conditions the reproductive seasonality of the fallow deer is well defined and may be related to photoperiod.

Delayed onset of puberty in male offspring from bisphenol A-treated dams is followed by the modulation of gene expression in the hypothalamic-pituitary-testis axis in adulthood.

Bisphenol A (BPA) is a synthetic endocrine-disrupting chemical of high prevalence in the environment, which may affect the function of the hypothalamic-pituitary-testis (HPT) axis in adult rats. The aim of the present study was to evaluate whether exposure to BPA during hypothalamic sexual differentiation at doses below the reproductive no observable adverse effect level of the World Health Organization causes changes in the regulation of the HPT axis. For this, 0.5 or 5mgkg-1 BPA was injected subcutaneously to the mothers from gestational day 18 to postnatal day (PND) 5. In adulthood (PND90), the mRNA expression of genes related to HPT axis was evaluated in hypothalamus, pituitary and testis. Hypothalamic expression of gonadotrophin-releasing hormone (Gnrh) and estrogen receptor 2 (Esr2) mRNA was increased in both BPA-treated groups compared to control group. In the pituitary, follicle stimulating hormone beta subunit (Fshb) and androgen receptor (Ar) mRNA expression was increased compared to control group in rats treated with 0.5mgkg-1 of BPA, whereas estrogen receptor 1 (Esr1) mRNA expression was only increased in the group treated with 5mgkg-1of BPA, compared to control group. In the testis, there was increased expression of FSH receptor (Fshr) and inhibin beta B subunit (Inhbb) transcripts only in rats treated with 0.5mgkg-1 of BPA. Serum testosterone and LH concentrations were increased in the group treated with 5mgkg-1of BPA. The results of the present study demonstrate for the first time that perinatal exposure to low doses of BPA during the critical period of hypothalamic sexual differentiation modifies the activity of the HPT axis in the offspring, with consequences for later life in adult rats.

The use of altrenogest to avoid hyperestrogenism after eCG-hCG ovulation induction in southern tigrina (Leopardus guttulus).

The goal of this study was to optimize an ovulation induction protocol for use with artificial insemination in the southern tigrina (Leopardus guttulus). The specific aims were to report the efficacy of using altrenogest, an oral progestin (Regumate, MSD Animal Health, Merck Animal Health), to suppress ovarian activity and prevent follicular hyperstimulation and hyperestrogenism after the administration of exogenous eCG and hCG. To monitor ovarian responses, fecal estrogen and progestogen metabolites were quantified by enzyme immunoassay in females before and after intramuscular administration of 200-IU eCG and 150-IU hCG in two trials, 4 months apart. During the first trial, there was no use of altrenogest, only the eCG-hCG ovulation induction protocol. In the second trial, the ovulation induction protocol was preceded by the administration of oral altrenogest for 14 days (minimum of 0.192 mg per kg per day). Altrenogest administration resulted in a suppression of follicular activity in three out of six females before eCG-hCG administration on the basis of lower mean estrogen concentrations (P < 0.05). It also resulted in four out of six females presenting lower fecal estrogen metabolite concentrations (P < 0.05) after ovulation induction, and two out of six individuals showed a reduction (P < 0.05) in postovulatory fecal progestogen metabolite concentrations, all when compared to the same female's cycles without the progestin. Fecal estrogen metabolite concentrations were closer to baseline in 50% of these individuals after altrenogest and eCG-hCG treatments when compared to basal concentrations before gonadotropins without the use of altrenogest. This study reported that use of altrenogest in southern tigrina can suppress ovarian activity and avoid hyperestrogenism after administration of eCG and hCG treatment. However, not all females responded uniformly, so more studies are needed to increase the efficacy of ovulation induction for use with artificial insemination in this species.

Relation between the level of self-mutilation and the concentration of fecal metabolites of glucocorticoids incaptive chimpanzees (Pan troglodytes) / Relação do grau de automutilação com as concentrações de metabólitos fecais de glicocorticoides em chimpanzés (Pan troglodytes)

The influence of stress in an environment, according with the behavioral and endocrine variables of primates, are increasingly being studied by a diversity of authors, and have shown that abnormal behaviors associated with increased glucocorticoids may be directly related with the impairment of their well-being. In this work were used 22 adult chimpanzees (Pan troglodytes), 11 males and 11 females, kept in captivity in three different institutions. All animals had their behavior registered by focal session using a 30 seconds sample interval, during six months, totaling 4,800 registries per each animal. During this period, fecal samples were collected 3 times a week for the extraction and measurement of the concentration of fecal metabolites of glucocorticoid by radioimmunoassay. Of the total observed, stereotypical behaviors represented 13,45±2.76%, and among them, self-mutilation represented 38.28±3.98 %. The animals were classified into three different scores, according with the percentage of body surface with alopecia due to self-mutilation. It was found a positive correlation of high intensity between the scores of alopecia due to the observed mutilation and the average concentrations of fecal metabolites of glucocorticoids. This result strongly suggests that this measurement of self-mutilation in a chimpanzee can be used as an important auxiliary tool to evaluate de conditions of adaptation of an animal in captivity, functioning as a direct indicator of the presence of chronic stress...

A influência do estresse de um ambiente nas variáveis endócrino-comportamentais de primatas vem sendo cada vez mais estudada por diversos autores, e mostram que comportamentos anormais associados a aumentos de glicocorticóides podem estar diretamente relacionados ao comprometimento do bem-estar. Neste trabalho foram utilizados 22 chimpanzés (Pan troglodytes) adultos, sendo 11 machos e 11 fêmeas mantidos em cativeiro de três instituições diferentes. Todos os animais tiveram seus comportamentos registrados pelo método de amostragem focal por intervalo de tempo, durante seis meses, totalizando 4800 registros para cada animal. Amostras fecais foram coletadas três vezes por semana, durante este período, para extração e dosagem de metabólitos fecais de glicocorticoides por radioimunoensaio. Os comportamentos estereotipados representaram 13,45+2,76% do total observado, sendo que dentre estes comportamentos a automutilação representou 38,28+3,98%. Os animais foram classificados em três graus diferentes, de acordo com o percentual da superfície corpórea com alopecia decorrente da automutilação. Foi encontrada uma correlação positiva de intensidade forte entre os graus de alopecia decorrentes de mutilação observados e as médias de concentrações de metabólitos fecais de glicocorticoides. Este resultado sugere fortemente que esta graduação de automutilação de um chimpanzé possa ser utilizada como uma ferramenta auxiliar importante nas avaliações das condições de adaptação do animal ao cativeiro, atuando como um indicador indireto da presença de estresse crônico...

Seasonal variation in urinary and salivary reproductive hormone levels in Amazonian manatees (Trichechus inunguis).

The Amazonian manatee (Trichechus inunguis) is a threatened aquatic mammal endemic to the Amazon basin. The aim of this study was to evaluate the urinary and salivary reproductive hormone levels of captive Amazonian manatees collected during two seasons of the year. Salivary samples from four males and urinary and salivary samples from three females were collected during two seasons (March-June and September-November) over two consecutive years. Salivary testosterone in males was measured by radioimmunoassay and reproductive hormones in females (salivary progesterone and oestradiol and urinary progestogens, oestrogens and luteinising hormone) were measured by enzyme immunoassay. The data were analysed in a 2×2 factorial design, where the factors were year and season. There was no effect of year or season for salivary testosterone. All female hormones showed a seasonal effect (higher hormone levels during March-June than September-November) or an interaction between year and season (P<0.05). These results strongly indicate the existence of reproductive seasonality in Amazonian manatees; however, apparently only females exhibit reproductive quiescence during the non-breeding season. Further long-term studies are necessary to elucidate which environmental parameters are related to reproductive seasonality in T. inunguis and how this species responds physiologically to those stimuli.

First attempt to monitor luteinizing hormone and reproductive steroids in urine samples of the Amazonian manatee (Trichechus inunguis).

The aims of this study were to validate an enzyme immunoassay (EIA) for the measurement of luteinizing hormone (LH) in urine samples of Amazonian manatees (Trichechus inunguis; Mammalia: Sirenia) and to monitor urinary LH and reproductive steroids during the ovarian cycle in this species. Urine samples were collected from two captive males following a hormonal challenge with a gonadotropin-releasing hormone (GnRH) analogue. The urinary LH results from hormonal challenge were compared with urinary androgens for the purpose of EIA validation. Furthermore, urine samples were collected daily, over a 12-wk period, from two captive adult females, for 2 consecutive yr. The urinary LH pattern from females was compared with the patterns of urinary progestagens and estrogen conjugates throughout the ovarian cycle. An LH peak was observed in both male Amazonian manatees after the hormonal challenge, occurring prior to or together with peak androgen levels. In the females, the ovarian cycle ranged from 40 to 48 days (mean of 43.7 days). Two distinct peaks of estrogen conjugates were observed across all cycles analyzed, and the urinary LH peaks observed were accompanied by peaks of urinary estrogen conjugates. The EIA was validated as a method for the quantification of urinary LH from Amazonian manatees, as it was able to detect variations in the levels of LH in urine samples. These results suggest that T. inunguis exhibits a peculiar hormonal pattern during the ovarian cycle. Therefore, further studies are desirable and necessary to clarify the relationship between this hormonal pattern and morphological changes, as well as mating behavior, in Amazonian manatee.

Endocrine monitoring of the ovarian cycle in captive female Amazonian manatees (Trichechus inunguis).

The Amazonian manatee (Trichechus inunguis; Mammalia: Sirenia), a threatened aquatic mammal endemic to the Amazon basin, is the only sirenian that lives exclusively in fresh water. Information about the reproductive endocrinology of the Amazonian manatee is scarce; therefore, the aim of this study was to monitor salivary progesterone and estradiol patterns during the ovarian cycle in T. inunguis. Salivary samples were collected daily during a 12-week period of two consecutive years from two captive adult females. The salivary estradiol and progesterone were measured by enzyme immunoassay. The results were analyzed in an iterative process of excluding values that were higher than the mean plus 2 standard deviations until the basal values were determined. The interval between two peaks of salivary estradiol followed by a rise of progesterone was considered as one complete cycle for the calculation of the cycle length. We observed only three complete cycles in all samples analyzed. The cycle length ranged from 42 to 48 days (mean of 44.67 days). We also observed two distinct salivary estradiol peaks during all cycles analyzed, with the first peak occurring before the rise in salivary progesterone and the second occurred followed by a return to basal progesterone levels. This is the first in-depth study of the ovarian cycle in Amazonian manatees. Our results demonstrate that salivary samples can be a useful tool in the endocrine monitoring of this species and suggest that T. inunguis shows a peculiar hormonal pattern during the ovarian cycle, a finding that may have physiological and ecological significance in the reproductive strategy of these animals.

Comparison of two methods for glucocorticoid evaluation in maned wolves / Comparação de dois métodos para avaliação de glicocorticóides em lobos guarás

Analysis of faecal glucocorticoid metabolites provides a powerful noninvasive tool for monitoring adrenocortical activity in wild animals. However, differences regarding the metabolism and excretion of these substances make a validation for each species and sex investigated obligatory. Although maned wolves (Chrysocyon brachyurus) are the biggest canids in South America, their behaviour and physiology are poorly known and they are at risk in the wild. Two methods for measuring glucocorticoid metabolites in maned wolves were validated: a radio- and an enzyme immunoassay. An ACTH challenge was used to demonstrate that changes in adrenal function are reflected in faecal glucocorticoid metabolites. Our results suggest that both methods enable a reliable assessment of stress hormones in maned wolves avoiding short-term rises in glucocorticoid concentrations due to handling and restraint. These methods can be used as a valuable tool in studies of stress and conservation in this wild species.

A análise de metabólitos de glicocorticóides fecais é uma ferramenta não-invasiva poderosa para o monitoramento da atividade adrenal em animais silvestres. Entretanto, diferenças no metabolismo e na excreção dessas substâncias tornam obrigatória a validação desse método para cada espécie e sexo investigado. Embora os lobos guarás (Chrysocyon brachyurus) sejam os maiores canídeos da América do Sul, seu comportamento e fiisiologia são ainda pouco conhecidos e estes animais são ameaçados. Dois métodos para mensuração de metabólitos de glicocorticóides em lobos guarás foram validados: um radio- e um enzima- imuno-ensaio. Um desafiio de ACTH foi usado para demonstrar que alterações no funcionamento adrenal podem ser detectadas nas concentrações metabólitos de glicocorticóides fecais. Nossos resultados sugerem que ambos os métodos possibilitam uma avaliação confiiável dos hormônios relacionados ao estresse em lobos guarás, evitando assim aumentos de curta duração nas concentrações glicocorticóides, devidos ao manejo e contenção. Esses métodos podem ser usados como uma ferramenta valiosa em estudos de estresse e conservação com essa espécie silvestre.

Identificação dos níveis séricos do fator de crescimento tipo insulina 1 em potros com osteocondrose / Identification of insulin-like growth factor-I serum levels in foals with osteo-chondrosis

A osteocondrose é uma das doenças ortopédicas do desenvolvimento mais comuns em cavalos, e deve ser encarada como uma desordem multifatorial. Caracteriza-se por ser uma doença dinâmica, onde o processo de reparo inicia-se quase que imediatamente após a formação da lesão osteocondral. A intensidade e eficácia deste reparo são fortemente relacionados à idade, e estão associados a reposição dos componentes da matriz cartilagínea. Uma vez que o fator de crescimento tipo insulina-1 (IGF-1) age regulando o crescimento da cartilagem articular, este estudo objetivou descrever os níveis séricos de IGF-I, insulina e glicose em potros Puro Sangue Lusitano hígidos ou com osteocondrose, desde o nascimento até 18 meses de idade. Dos potros acompanhados, 76,08 por cento apresentaram sinais radiográficos de osteocondrose com um mês de idade, porém somente 16,2 por cento mantiveram as lesões aos 18 meses. As concentrações de IGF-1 alcançaram picos entre 14 e 16 meses, equivalente ao início da puberdade. As concentrações de IGF-1 nos potros com osteocondrose foram menores que potros sadios, aos 2 e 5 meses (P<0,05), e os de insulina aos 2 meses (P<0,05). Em criatórios com alta ocorrência de osteocondrose recomenda-se que as mensurações dos níveis séricos de IGF-1 e insulina ocorram durante os primeiros 6 meses de idade, para que haja tempo hábil de se estabelecer medidas profiláticas e de tratamento.

Osteochondrosis is the most common orthopaedic developmental disorder in horses and has been traditionally defined as a multifactorial disease. The disease had a very dynamic character in which the repair process starts almost immediately after the lesion has formed. The intensity and efficacy of this repair process is strongly age-related and is determined by the turnover rate of the components of the extracellular matrix of the articular cartilage. Since the insulin-like growth factor-I (IGF-1) acts regulating the growth of articular cartilage, this study aimed to describe the serum levels of IGF-1, insulin and glucose in healthy Lusitano foals and foals with osteochondrosis, from birth to 18 months of age. At one month 76.08 percent of the foals showed radiographic signs of osteochondrosis, but at age of 18 months the percentage dropped to 16.2 percent. The IGF-1 concentrations reached peak values at age of 14 to 16 months, equivalent to the onset of puberty. The IGF-1 concentrations in foals with osteochondrosis were lower than in healthy 2 to 5-month-old foals (P<0.05), and the insulin at age of 2 months (P<0.05). On farms with high incidence of osteocondrosis is recommended that measurement of serum IGF-1 and insulin occur during the first 6 months of age, to have enough time to establish preventive and therapeutic measures.

Validação de um radioimunoensaio para a quantificação de metabólitos fecais de testosterona em hamster Sírio (Mesocricetus auratus) / Validation of a radioimmunoassay for the quantification of fecal testosterone metabolites in the Syrian hamster (Mesocricetus auratus)

Modelo para o estudo de diversas doenças humanas, o hamster tem sido objeto de numerosos estudos comportamentais e envolvendo estresse e/ou comportamento agonístico que supõem, muitas vezes, o monitoramento das flutuações hormonais nos indivíduos envolvidos. O objetivo do presente trabalho foi confirmar a adequação de um conjunto comercial para dosagem de testosterona em sangue humano para a quantificação de metabólitos fecais de testosterona (MFT) em hamsters Sírios machos e fêmeas. Dez machos foram submetidos a um desafio com um agonista de GnRH para estimular a atividade testicular, elevando os níveis circulantes de testosterona. Cinco fêmeas receberam uma injeção de testosterona enquanto cinco outras receberam uma injeção de solução salina. Amostras de fezes coletadas antes e depois dos procedimentos, assim como amostras fecais de 20 fêmeas gestantes coletadas ao longo da gestação foram analisadas com um conjunto comercial para radioimunoensaio. Um pico de MFT 12h após a injeção seguido de uma queda abaixo do nível basal comprovou que, nos machos, as alterações nos níveis de MFT refletem as alterações da concentração de testosterona no sangue. Nestes observou-se um ciclo circadiano das concentrações de MFT com acrofase no início do período claro correspondendo ao ciclo descrito para as concentrações sanguíneas na literatura. Nas fêmeas a administração de testosterona exógena provocou uma elevação importante dos níveis de MFT, mas as concentrações medidas ao longo da gestação não refletiram o padrão dos níveis sanguíneos do hormônio endógeno. O conjunto para radioimunoensaio para testosterona em sangue humano mostrou-se adequado para o monitoramento da função testicular no hamster macho, mas um ensaio mais específico seria necessário para as fêmeas.

Besides being models for a variety of human diseases, hamsters have been object of numerous behavioral studies about stress and agonistic behavior. Such studies usually involve hormone change monitoring. The aim of the present study was to confirm the suitability of a commercial kit for human serum testosterone analysis to quantify testosterone metabolites in the feces (MFT) of male and female Syrian hamsters. Ten males were submitted to a GnRH challenge test to stimulate testicular activity and increase circulating testosterone levels. Five females received a testosterone injection and five other females were given a saline injection. Fecal samples collected before and after the procedures, and fecal samples collected from 20 pregnant females through gestation were analyzed for MFT with a commercial radioimmunoassay. The detection of a MFT peak 12 h after GnRH administration followed by a decrease under baseline showed that, in males, changes in the levels of MFT are related to respective changes of testosterone concentrations in the blood. Again in males a circadian cycle of MFT similar to the circadian rhythm described in literature for blood concentrations was detected. The administration of exogenous testosterone caused in females a dramatic peak of MFT. However, the concentrations measured through gestation did not reflect the pattern of endogenous testosterone blood levels as described in the literature. Therefore, the use of a radioimmunoassay for human blood testosterone was validated in male Syrian hamster, but a more specific assay would be necessary for female hamsters.

Insulin affects tissue organization and the kinetics of epithelial cell death in the rat ventral prostate after castration.

Prostate growth and physiology are regulated by steroid hormones and modulated by multiple endocrine factors. We investigated the action of insulin on the tissue organization and kinetics of epithelial cells in the rat ventral prostate (VP) in response to castration up to 120 hours after surgery by using an acute protocol of alloxan-induced diabetes. Diabetes caused a reduction in volume density (V(v%)) and volume of the epithelium. The effects of castration on the epithelium were accelerated in the diabetic animals, as determined by changes in V(v%) and volume. The smooth muscle cells became atrophic and apparently relaxed in response to castration, in contrast to the spinous aspect observed in nondiabetic castrated rats. Counting of apoptotic nuclei in the epithelium showed the classical apoptosis peak at 72 hours in nondiabetic rats and an advance of the apoptosis peak to 48 hours after castration in diabetic rats. Insulin restored the time of the peak to 72 hours. These results were confirmed after immunostaining for cleaved caspase-3 and suggest a survival and antiapoptotic effect on VP epithelial cells in both the presence and absence of androgen stimulation. This idea is supported by the observation that insulin also reduced the overall rate of apoptosis at all experimental points analyzed before and after castration.

Efeitos in vivo de resina dental á base de metacrilato glicerolato (BISGMA) na Puberdade de ratos wistar / Nursing diagnosis in the post operative period of cardiac surgery

This study aimed to determine the effects of the application of sealant in dental element and its possible influence on the reproductive development and hormonal profile in male Wistar rats as experimental models. Thirty-two male Wistar rats were randomly allocated in four groups, from 23PND (Post Natal Day) to 53PND. They were treated with autopolymerizable or photopolymerizable dental sealant (BISGMA), estradiol cipionate (positive control) or saline solution (negative control). The effects were monitored by the body weight gain, serum concentration of testosterone and estradiol, and by the structure of the seminiferous tubules. Both dental sealants caused alterations in germinative epithelium of the seminiferous tubules, but they didn´t interfere in hormonal serum levels of testosterone or estradiol, neither in body development. It´s possible to conclude that the application of dental sealant in prepubertal period causes damages to the testicular structure, with reduction of the tubular epithelium.

O presente estudo teve como objetivos determinar os efeitos da aplicação de selante de cicatrículas e fissuras em elemento dentário sobre o desenvolvimento reprodutivo masculino pré-púbere e perfil hormonal. Utilizaram-se 32 ratos Wistar machos alocados em 4 grupos dos 23º aos 53º dias de idade e tratados com uma das duas formulações comerciais de selantes dentários à base de dimetacrilato (BISGMA), uma utopolimerizável e outro fotopolimerizável, um grupo com cipionato de estradiol (controle positivo) e outro com solução salina (controle negativo). As possíveis alterações foram avaliadas pelo ganho de peso corporal, concentração sérica de testosterona e estradiol e características estruturais dos testículos. Notou-se que a administração do selante nas suas duas formas, auto-polimerizável e foto-polimerizável, causou alteração no epitélio germinativo dos túbulos seminíferos, mas sem alterações nas concentrações hormonais de estradiol e testosterona. Com base nesse estudo, foi possível concluir que a administração de selantes dentários em ratos Wistar machos pré-púberes, acarreta danos ao epitélio dos túbulos seminíferos constatadas por mudanças na estrutura testicular com redução do epitélio tubular.

Assessment of the physiologic stress response by quantification of fecal corticosteroids.

Noninvasive techniques to monitor reproductive or stress hormones are now widely used in captive and free-ranging wildlife. These methods offer great advantages and deserve to be used also in laboratory rodents. However, we remain naïve about factors that may influence the accuracy of these techniques. The aim of this study was to evaluate the adequacy of measuring the concentration of cortisol fecal metabolites to assess the physiologic stress response. Ten adult female Syrian hamsters were ovariectomized, and all feces voided were collected daily for 4 d before and 5 d after surgery. Cortisol fecal metabolites were extracted and quantified by radioimmunoassay. We determined per-gram fecal cortisol metabolite concentrations, total 24-h fecal output and total 24-h fecal cortisol metabolite production. Surgery considerably affected fecal output, and using per-gram versus total cortisol metabolites led to different conclusions: whereas concentrations increased significantly just after ovariectomy and decreased on subsequent days, the total excreted cortisol metabolites varied in a symmetrical pattern. Therefore, the relative per-gram measure of hormones may not reflect the total amount of circulating hormones, because these measures are comparable only if the volume of the material in which the hormone is contained is the same in the 2 groups.

Control of musth in an Asian elephant bull (Elephas maximus) using leuprolide acetate.

The results of long-term administration of leuprolide acetate (LA) depot in a 52-yr-old Asian elephant bull (Elephas maximus) for control of musth are presented. Twelve injections were administered for 6 yr during our interpretation of early musth or "premusth." Intervals between musth periods during the study varied from 2 to 34 mo. Blood samples, drawn weekly, were assayed for serum testosterone concentrations; mean levels were 11.78 +/- 1.97 nmol/L throughout the first 26 mo of the study, 7.28 +/- 1.28 nmol/L during the following 21 mo, and 0.45 +/- 0.035 nmol/L in the last 34 mo of this study. Early musth signs ceased within 3 days of drug administration after 10 of 12 injections. The mean serum testosterone concentrations were significantly decreased by the last 34 mo of the study. The results suggest leuprolide is a suitable alternative for controlling or preventing (or both) musth in captive Asian elephants, although permanent reproductive effects may occur. Zoos and wildlife conservation institutions could benefit from the use of LA in Asian elephants to increase the male availability in captivity, consequently ensuring genetic diversity and the perpetuation of the species.