RESUMO
Prevention of dementia is important, because it is a leading cause of disability in elderly people. We previously reported that acute intraperitoneal treatment with N-acetyl-5-methoxy kynuramine (AMK), a melatonin (MEL) metabolite, enhanced long-term object recognition memory in ICR mice, a MEL deficient strain. Despite the presumable availability of AMK for dementia, its effects on cognitive performance have not been elucidated. It is unclear whether endogenous AMK is responsible for modulating long-term memory performance. To address this question, we assessed the effects of endogenous AMK on learning and memory using an object recognition test. C3H mice, a MEL-proficient strain, showed peak MEL levels at zeitgeber times (ZT) 19 and 22. Object recognition memory at ZT20 was superior to that at ZT8. Norharmane (NHM, 100 mg/kg), an indoleamine-2,3-dioxygenase (IDO) inhibitor, prevented the transformation of MEL to AMK, thereby suppressing AMK synthesis at ZT20. NHM (100 mg/kg) and another IDO inhibitor, 1-methyl-L-tryptophan (1-MT, 100 mg/kg), disrupted elevated cognitive performance at ZT20. These data imply that endogenous AMK may play a physiological role in the modulation of cognitive function. We also investigated the effects of pharmacological doses of MEL and AMK on object recognition memory in young C3H mice. MEL administration of 0.1 mg/kg, but not 0.01 mg/kg, enhanced object recognition memory, whereas 0.01 and 1 mg/kg AMK enhanced object recognition memory. Administration of 0.1 and 1 mg/kg AMK also enhanced object recognition memory in old C3H mice. These findings in MEL-proficient mice should be confirmed in other learning and memory tests before encouraging the clinical use of AMK.
Assuntos
Demência , Melatonina , Masculino , Camundongos , Animais , Cinuramina/metabolismo , Cinuramina/farmacologia , Camundongos Endogâmicos C3H , Camundongos Endogâmicos ICR , Antioxidantes/metabolismo , Melatonina/metabolismoRESUMO
Melatonin (MEL) has been reported to enhance cognitive processes, making it a potential treatment for cognitive decline. However, the role of MEL's metabolites, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK), in these effects are unknown. The current study directly investigated the acute effects of systemic MEL, AFMK, and AMK on novel object recognition. We also analyzed MEL, AFMK, and AMK levels in hippocampus and temporal lobe containing the perirhinal cortex following systemic MEL and AMK treatment. AMK administered post-training had a more potent effect on object memory than MEL and AFMK. AMK was also able to rescue age-associated declines in memory impairments when object memory was tested up to 4 days following training. Results from administering AMK at varying times around the training trial and the metabolism time course in brain tissue suggest that AMK's memory-enhancing effects reflect memory consolidation. Furthermore, inhibiting the MEL-to-AMK metabolic pathway disrupted object memory at 24 hours post-training, suggesting that endogenous AMK might play an important role in long-term memory formation. This is the first study to report that AMK facilitates long-term object memory performance in mice, and that MEL crosses the blood-brain barrier and is immediately converted to AMK in brain tissue. Overall, these results support AMK as a potential therapeutic agent to improve or prevent memory decline.
Assuntos
Comportamento Animal/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Cinuramina/análogos & derivados , Melatonina/farmacologia , Memória de Longo Prazo/efeitos dos fármacos , Lobo Temporal/efeitos dos fármacos , Fatores Etários , Animais , Biotransformação , Hipocampo/metabolismo , Cinuramina/metabolismo , Cinuramina/farmacologia , Masculino , Melatonina/deficiência , Melatonina/genética , Camundongos Endogâmicos ICR , Teste de Campo Aberto , Lobo Temporal/metabolismo , Fatores de TempoRESUMO
Our previous study in male rats demonstrated that bilateral administration of flutamide, an androgen receptor (AR) antagonist, into the posterodorsal medial amygdala (MePD) increased the time sniffing male odors to as high as that sniffing estrous odors, eliminating the preference for estrous odors over male odors. This made us speculate that under blockade of AR in the MePD, testosterone-derived estrogen acting on the same brain region arouses interest in male odors which is otherwise suppressed by concomitant action of androgen. In cyclic female rats, endogenous androgen has been thought to be involved in inhibitory regulation of estrogen-activated sexual behavior. Thus, in the present study, we investigated the possibility that in female rats the arousal of interest in male odors is also normally regulated by both estrogen and androgen acting on the MePD, as predicted by our previous study in male rats. Implantation of either the estrogen receptor blocker tamoxifen (TX) or a non-aromatizable androgen 5α-dihydrotestosterone (DHT) into the MePD of ovariectomized, estrogen-primed female rats eliminated preference for male odors over estrous odors by significantly decreasing the time sniffing male odors to as low as that sniffing estrous odors. The subsequent odor discrimination tests confirmed that the DHT and TX administration did not impair the ability to discriminate between male and estrous odors. These results suggest that in estrous female rats estrogen action in the MePD plays critical roles in the expression of the preference for male odors while androgen action in the same brain region interferes with the estrogen action.
Assuntos
Tonsila do Cerebelo/efeitos dos fármacos , Comportamento de Escolha/efeitos dos fármacos , Estrogênios/farmacologia , Casamento , Odorantes , Comportamento Sexual Animal/efeitos dos fármacos , Testosterona/farmacologia , Tonsila do Cerebelo/metabolismo , Tonsila do Cerebelo/fisiologia , Animais , Complexo Nuclear Corticomedial/efeitos dos fármacos , Complexo Nuclear Corticomedial/metabolismo , Di-Hidrotestosterona/farmacologia , Estro/efeitos dos fármacos , Feminino , Flutamida/farmacologia , Masculino , Casamento/psicologia , Ratos , Ratos Long-Evans , Receptores Androgênicos/metabolismo , Comportamento Sexual/efeitos dos fármacos , Comportamento Sexual Animal/fisiologiaRESUMO
Fish scales are a form of calcified tissue similar to that found in human bone. In medaka scales, we detected both osteoblasts and osteoclasts and subsequently developed a new scale assay system. Using this system, we analyzed the osteoblastic and osteoclastic responses under 2-, 3-, and 4-gravity (G) loading by both centrifugation and vibration. After loading for 10 min, the scales from centrifugal and vibration loading were incubated for 6 and 24 hrs, respectively, after which the osteoblastic and osteoclastic activities were measured. Osteoblastic activity significantly increased under 2- to 4-G loading by both centrifugation and vibration. In contrast, we found that osteoclastic activity significantly decreased under 2- and 3-G loading in response to both centrifugation and vibration. Under 4-G loading, osteoclastic activity also decreased on centrifugation, but significantly increased under 4-G loading by vibration, concomitant with markedly increased osteoblastic activity. Expression of the receptor activator of the NF-κB ligand (RANKL), an activation factor of osteoclasts expressed in osteoblasts, increased significantly under 4-G loading by vibration but was unchanged by centrifugal loading. A protein sequence similar to osteoprotegerin (OPG), which is known as an osteoclastogenesis inhibitory factor, was found in medaka using our sequence analysis. The ratio of RANKL/OPG-like mRNAs in the vibration-loaded scales was significantly higher than that in the control scales, although there was no difference between centrifugal loaded scales and the control scales. Accordingly, medaka scales provide a useful model by which to analyze bone metabolism in response to physical strain.
Assuntos
Hipergravidade , Oryzias/anatomia & histologia , Osteoblastos/fisiologia , Osteoclastos/fisiologia , Sequência de Aminoácidos , Animais , Fenômenos Biomecânicos , Regulação da Expressão Gênica/fisiologia , Osteoblastos/citologia , Osteoclastos/citologia , Osteoprotegerina/genética , Osteoprotegerina/metabolismoRESUMO
Benzodiazepines are widely prescribed for patients suffering from anxiety and insomnia. Although amnesic effects of benzodiazepines are commonly known as side effects, it has also been reported that these drugs improve memory for information learned before drug intake, a phenomenon called retrograde facilitation. However, the retrograde effects of benzodiazepines on cognitive performances in rodents remain controversial. It should be considered that studies on diazepam-induced retrograde facilitation in humans have been conducted using a recall paradigm focused on short-term memory, whereas these studies in rodents have been conducted using memory tasks that mainly target long-term memory and/or require negative or positive reinforcers. In the current study, we investigated whether diazepam, a benzodiazepine, induces retrograde facilitation for object recognition memory and spatial memory in mice, using a novel object recognition test and an object location test, respectively. These tests are available for short-term memory and do not require any reinforcer. The mice treated with diazepam retained object recognition memory for at least 180 min and spatial memory for at least 150 min. In contrast, vehicle-treated control mice retained object recognition memory for 120 min but not 150 min or longer, and spatial memory for 90 min but not 120 min or longer. These data clearly demonstrated diazepam-induced retrograde facilitation for both object recognition and spatial memories in mice. The present study is expected to contribute to the elucidation of the neural basis of retrograde facilitation.
Assuntos
Diazepam , Reconhecimento Psicológico , Camundongos , Humanos , Masculino , Animais , Diazepam/farmacologia , Benzodiazepinas , Memória de Longo Prazo , Memória Espacial , RoedoresRESUMO
OBJECTIVES: Melatonin (MEL) has been reported to enhance cognitive performance. Recently, we have demonstrated that a MEL metabolite N-acetyl-5-methoxykynuramine (AMK) promoted the formation of long-term object recognition memory more potently than MEL. Here, we examined the effects of 1 mg/kg MEL and AMK on both object location memory and spatial working memory. We also investigated the effects of the same dose of these drugs on relative phosphorylation/activation levels of memory-related proteins in the hippocampus (HP), the perirhinal cortex (PRC) and the medial prefrontal cortex (mPFC). METHODS: Object location memory and spatial working memory were assessed using the object location task and the Y-maze spontaneous alternation task, respectively. Relative phosphorylation/activation levels of memory-related proteins were assessed using western blot analysis. RESULTS: AMK, as well as MEL, enhanced object location memory and spatial working memory. AMK increased the phosphorylation of cAMP-response element-binding protein (CREB) in both the HP and the mPFC 2 h after the treatment. AMK also increased the phosphorylation of extracellular signal-regulated kinases (ERKs) but decreased that of Ca2+/calmodulin-dependent protein kinases II (CaMKIIs) in the PRC and the mPFC 30 min after the treatment. MEL increased CREB phosphorylation in the HP 2 h after the treatment, whereas no detectable changes in the other proteins examined were observed. CONCLUSION: These results suggested the possibility that AMK exerts stronger memory-enhancing effects than MEL by more remarkably altering the activation of memory-related proteins such as ERKs, CaMKIIs and CREB in broader brain regions, including the HP, mPFC and PRC, compared to MEL.
Assuntos
Melatonina , Memória de Curto Prazo , Fosforilação , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina , MAP Quinases Reguladas por Sinal Extracelular , Memória de Longo Prazo , Proteína de Ligação ao Elemento de Resposta ao AMP CíclicoRESUMO
We recently demonstrated that a single post-training administration of either melatonin, an MT1/MT2 melatonin receptor agonist ramelteon, or a brain melatonin metabolite N1-acetyl-5-methoxyquinuramine (AMK) enhanced object recognition memory. The present study aims to investigate the effects of melatonin, ramelteon, and AMK on relative phosphorylation levels of memory-related proteins in order to explore candidate signaling pathways associated with the receptor-mediated and nonreceptor-mediated memory-enhancing effects of melatonin. We first confirmed that post-training administration of either melatonin, ramelteon, or AMK at 1â mg/kg promoted long-term memory formation, using the novel object recognition task. Next, the effects of the same doses of these drugs on relative phosphorylation levels of the extracellular signal-regulated kinase (ERK) and calcium/calmodulin-dependent kinases (CaMKs) in the hippocampus and the perirhinal cortex (PRC) were examined by western blot analysis. In the hippocampus, treatment with ramelteon or AMK significantly increased and decreased phosphorylation levels of ERK and cAMP-response element binding protein (CREB) and those of CaMKIIα and ß, respectively. In the PRC, phosphorylation levels of ERK and those of CaMKIIß were significantly increased by both ramelteon and AMK and by ramelteon, respectively. Neither ramelteon nor AMK altered the phosphorylation levels of CaMKIV in either hippocampus or PRC. These results suggest that melatonin may be involved in promoting the formation of long-term object recognition memory in a similar, if not identical, manner by modulating the phosphorylation levels of memory-related proteins such as ERK, CaMKIIs, and CREB in both receptor-mediated and nonreceptor-mediated signaling pathways.
Assuntos
Melatonina , Córtex Perirrinal , Masculino , Animais , Camundongos , Fosforilação , Melatonina/farmacologia , MAP Quinases Reguladas por Sinal Extracelular , Hipocampo , Proteína de Ligação ao Elemento de Resposta ao AMP CíclicoRESUMO
The present study was designed to investigate the role of androgen in the medial amygdala (MeA) in the expression of sexual odor preference in male rats. Gonadally intact, sexually experienced male rats received bilateral administration of flutamide, an androgen receptor (AR) blocker, aimed at either the posterior dorsal part (MePD) or the anterior dorsal part (MeAD) of the MeA through inner cannulae inserted into the implanted guide cannulae. Prior to flutamide administration, all subjects spent longer sniffing volatile odors from an estrous female than those from a sexually active male. Experiment 1 demonstrated that the preference for the female odors over the male odors was eliminated during flutamide administration into the MePD, but not into either the MeAD or outside MePD/MeAD. This elimination of the female-directed odor preference resulted from increase of time sniffing the male odors rather than decrease of time sniffing the estrous odors. In Experiment 2, odor discrimination tests confirmed that the flutamide administration into the MePD did not induce impairment in the ability of the subjects to discriminate the estrous odors from the male odors. These results demonstrated that activation of AR in the MePD plays a critical role in the expression of the preference for estrous odors over male odors. AR blockade, however, seemed to induce a preference for male odors rather than reduce the existing preference for estrous odors, suggesting a complicated regulation of sexual odor preference by sex steroids.
Assuntos
Tonsila do Cerebelo/fisiologia , Preferência de Acasalamento Animal , Odorantes , Percepção Olfatória/fisiologia , Receptores Androgênicos/fisiologia , Tonsila do Cerebelo/efeitos dos fármacos , Antagonistas de Receptores de Andrógenos/farmacologia , Animais , Estro , Detecção do Estro , Feminino , Flutamida/farmacologia , Masculino , Percepção Olfatória/efeitos dos fármacos , RatosRESUMO
Demasculinizing action of embryonic estrogen on crowing behavior in male Japanese quails was examined. Eggs were treated with either 20 microg of estradiol benzoate (EB) or vehicle on the 10th day of incubation. Chicks hatched from both groups of eggs were injected daily with either testosterone propionate (TP; 10 microg/g b.w.), 5alpha-dihydrotestosterone (DHT, a non-aromatizable androgen; 10 microg/g b.w.), or vehicle from 11 to 50 days after hatching, and during this period their calling behaviors were observed. Irrespective of embryonic treatments, all birds received posthatching treatment with either TP or DHT, but not with vehicle, emitted crows in place of distress calls in a stress (non-sexual) context of being isolated in a recording chamber. The posthatching TP, but not posthatching DHT, induced crowing in a sexual context (crowing in their home-cages) from much earlier age than posthatching vehicle in the birds received control embryonic treatment with vehicle. The same TP treatment, however, completely eliminated the crowing in a sexual context in the birds received EB during their embryonic life. In the birds treated with either posthatching DHT or posthatching vehicle, the crowing in a sexual context was only slightly decreased by embryonic EB treatment. These data suggest that posthatching estrogen, derived from testosterone aromatization, enhances the demasculinizing action of embryonic estrogen, and thus strongly reduces the sexual motivation for crowing behavior. This demasculinizing action, however, would not influence vocal control system which generates acoustic pattern of crowing in the presence of androgens allowing the birds to crow in a non-sexual context.
Assuntos
Coturnix/fisiologia , Di-Hidrotestosterona/farmacologia , Estradiol/análogos & derivados , Comportamento Sexual Animal/efeitos dos fármacos , Propionato de Testosterona/farmacologia , Vocalização Animal/fisiologia , Análise de Variância , Animais , Peso Corporal/efeitos dos fármacos , Cloaca/efeitos dos fármacos , Cloaca/crescimento & desenvolvimento , Coturnix/embriologia , Estradiol/farmacologia , Feminino , Masculino , Tamanho do Órgão/efeitos dos fármacos , Estresse Psicológico , Testículo/efeitos dos fármacos , Testículo/crescimento & desenvolvimentoRESUMO
Sexual behavior is a natural reward that activates mesolimbic dopaminergic system. Microdialysis studies have shown that extracellular level of dopamine (DA) in the nucleus accumbens (NAcc) significantly increases during copulation in male rats. The NAcc DA level is also known to be increased during the presentation of a sexually receptive female before mating. This rise in DA was probably associated with sexual motivation elicited by incentive stimuli from the receptive female. These microdialysis studies, however, did not thoroughly investigated if olfactory stimuli from estrous females could significantly increase the extracellular DA in the NAcc of male rats. The present study was designed to examine systematically the relationship between the expression of preference for the olfactory stimuli from estrous females and the effects of these stimuli on the extracellular DA levels in the NAcc measured by in vivo microdialysis in male Long-Evans (LE) rats. We used two types of olfactory stimuli, either airborne odors (volatile stimuli) or soiled bedding (volatile plus nonvolatile stimuli). The sexually experienced male rats, which experienced six ejaculations, significantly preferred both of these olfactory stimuli from estrous females as opposed to males. Exposure to these female olfactory stimuli gradually increased extracellular DA in the NAcc, which reached significantly higher level above baseline during the period following the removal of the stimuli although not during the 15-min stimulus presentation period. The sexually naïve male rats, on the other hand, showed neither preference for olfactory stimuli from estrous females nor increase in the NAcc DA after exposure to these stimuli. These data suggest that in male LE rats olfactory stimuli from estrous females in and of themselves can be conditional cues that induce both incentive motivation and a significant increase in the NAcc DA probably as a result of being associated with sexual reward through copulatory experience.
Assuntos
Dopamina/metabolismo , Estro , Núcleo Accumbens/metabolismo , Percepção Olfatória/fisiologia , Comportamento Sexual Animal/fisiologia , Animais , Cateteres de Demora , Estro/fisiologia , Feminino , Masculino , Microdiálise , Odorantes , Ratos Long-Evans , RecompensaRESUMO
In the present study in estrogen-progesterone primed ovariectomized female rats, we examined the expression of a preference for male odors and male odor-induced Fos immunoreactivity throughout the vomeronasal projection pathway and the nucleus accumbens (NAcc), using both sexually experienced and sexually naive subjects. Female rats significantly preferred airborne odors and soiled bedding from sexually active males over those from estrous females, irrespective of the presence or absence of prior sexual experience. On the other hand, the brain regions in which exposure to male-soiled bedding significantly increased Fos expression were different between sexually experienced and sexually naive subjects. Significant increment of Fos expression in the posterior-dorsal medial amygdala (MePD) and the bed nucleus of stria terminalis (BNST) in forebrain, as well as the accessory olfactory bulb, was observed in both groups of subjects. Fos expression in the anterior-dorsal medial amygdala (MeAD), the medial preoptic area (mPOA) and the NAcc core, however, was significantly increased only in the sexually experienced subjects. These results suggested that male odor-induced activations of the MePD and/or the BNST, but not of the MeAD, the mPOA and the NAcc core, are required for the expression of a male-directed odor preference in female rats.
Assuntos
Núcleo Accumbens/fisiologia , Condutos Olfatórios/fisiologia , Comportamento Sexual Animal/fisiologia , Olfato/fisiologia , Órgão Vomeronasal/fisiologia , Tonsila do Cerebelo/anatomia & histologia , Tonsila do Cerebelo/fisiologia , Animais , Feminino , Sistema Límbico/anatomia & histologia , Sistema Límbico/fisiologia , Masculino , Núcleo Accumbens/anatomia & histologia , Odorantes , Bulbo Olfatório/anatomia & histologia , Bulbo Olfatório/fisiologia , Condutos Olfatórios/anatomia & histologia , Ovariectomia , Área Pré-Óptica/anatomia & histologia , Área Pré-Óptica/fisiologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Long-Evans , Núcleos Septais/anatomia & histologia , Núcleos Septais/fisiologia , Caracteres SexuaisRESUMO
Male rats prefer odors from estrous females to those from sexually active males. Several studies, however, have demonstrated that prior sexual experience was required to develop the preference for estrous odor. Immunohistological methods for visualizing Fos protein have been shown that in sexually experienced male rats, estrous odors activate brain areas throughout the vomeronasal projection pathway (VN pathway) and the nucleus accumbens (NAcc). In the present study, we examined the contribution of prior sexual experience to the estrous odor-induced neuronal activation of these brain areas in relation to the development of the preference for estrous odor. Sexually experienced testosterone-implanted castrates showed the preference for the odor from an estrous female as opposed to the odor from a sexually active male. In these subjects, significant increment of Fos-like immunoreactivity (Fos-Li) after exposure to estrous female soiled bedding was observed in all brain regions examined, confirming the results of previous studies. Sexually naïve subjects, on the other hand, did not show the preference for estrous odor and the significant increment of Fos-Li was observed only in the accessory olfactory bulb (AOB) and the posterior-dorsal medial amygdala (MePD) of the VN pathway. These results suggested that sexual experience is required for the estrous odor-induced activation of more central portions of the VN pathway, such as the medial preoptic area (mPOA) and the bed nucleus of the stria terminalis (BNST), and the NAcc. The activation of some of these brain regions, therefore, is probably involved in the development of the preference for estrous odor.
Assuntos
Ciclo Estral/fisiologia , Núcleo Accumbens/fisiologia , Odorantes , Condutos Olfatórios/fisiologia , Comportamento Sexual Animal , Órgão Vomeronasal/fisiologia , Tonsila do Cerebelo/fisiologia , Animais , Implantes de Medicamento , Feminino , Genes fos/genética , Imuno-Histoquímica , Masculino , Orquiectomia , Área Pré-Óptica/fisiologia , Ratos , Ratos Long-Evans , Testosterona/administração & dosagem , Testosterona/farmacologiaRESUMO
Daily and circadian variations of melatonin contents in the diencephalic region containing the pineal organ, the lateral eyes, and plasma were studied in a urodele amphibian, the Japanese newt (Cynops pyrrhogaster), to investigate the possible roles of melatonin in the circadian system. Melatonin levels in the pineal region and the lateral eyes exhibited daily variations with higher levels during the dark phase than during the light phase under a light-dark cycle of 12 h light and 12 h darkness (LD12:12). These rhythms persisted even under constant darkness but the phase of the rhythm was different from each other. Melatonin levels in the plasma also exhibited significant day-night changes with higher values at mid-dark than at mid-light under LD 12:12. The day-night changes in plasma melatonin levels were abolished in the pinealectomized (Px), ophthalmectomized (Ex), and Px+Ex newts but not in the sham-operated newts. These results indicate that in the Japanese newts, melatonin production in the pineal organ and the lateral eyes were regulated by both environmental light-dark cycles and endogenous circadian clocks, probably located in the pineal organ and the retina, respectively, and that both the pineal organ and the lateral eyes are required to maintain the daily variations of circulating melatonin levels.
Assuntos
Ritmo Circadiano/fisiologia , Olho/metabolismo , Melatonina/sangue , Melatonina/metabolismo , Glândula Pineal/metabolismo , Salamandridae/fisiologia , Análise de Variância , Animais , Japão , FotoperíodoRESUMO
We examined the effects of the sex steroid milieu on sexual odor preference of sexually-experienced male rats using an alternate choice paradigm after endocrine manipulations. Gonadally intact (GI) males showed a male typical preference, i.e. spent longer time sniffing estrous females than males or ovariectomized females. At 1-2 weeks after orchidectomy (ORx), the males exhibited a transient preference for sexually vigorous males, a female typical preference pattern, followed by a total loss of preference after 4 weeks. Subcutaneous implantation of a Silastic capsule containing formestane (4-OHA), an aromatase inhibitor, had no effect on the preference of gonadally intact rats, but successfully prevented the emergence of the female typical preference after ORx. Capsules containing testosterone (T), dihydrotestosterone (DHT), or estradiol benzoate (EB), but not those with cholesterol (CH), restored masculine typical preference in ORx males at 2 weeks after the placement. The feminine preference for males was observed at 2-3 weeks after removal of T or EB capsules, but not by the removal of DHT and CH capsules. The results suggest that either exogenous androgen or estrogen maintains the masculine typical odor preference. Estrogen itself or produced through aromatization of circulating T, induces a transient feminine typical preference at a certain decreased titer during its disappearance from the circulation. Estrogen at different titers might determine appearance of masculine or feminine typical olfactory preference in adult ORx rats.
Assuntos
Percepção Olfatória/fisiologia , Orquiectomia , Receptores de Estrogênio/metabolismo , Comportamento Sexual Animal/fisiologia , Androgênios/administração & dosagem , Animais , Colesterol/administração & dosagem , Di-Hidrotestosterona/administração & dosagem , Estradiol/administração & dosagem , Estradiol/análogos & derivados , Estrogênios/administração & dosagem , Feminino , Masculino , Odorantes , Percepção Olfatória/efeitos dos fármacos , Estimulação Física , Psicotrópicos/administração & dosagem , Ratos Long-Evans , Comportamento Sexual Animal/efeitos dos fármacos , Testosterona/administração & dosagemRESUMO
To analyze the effect of polychlorinated biphenyl (PCB) 118 on fish bone metabolism, we examined osteoclastic and osteoblastic activities, as well as plasma calcium levels, in the scales of PCB (118)-injected goldfish. In addition, effect of PCB (118) on osteoclasts and osteoblasts was investigated in vitro. Immature goldfish, in which the endogenous effects of sex steroids are negligible, were used. PCB (118) was solubilized in dimethyl sulfoxide at a concentration of 10 ppm. At 1 and 2 days after PCB (118) injection (100 ng/g body weight), both osteoclastic and osteoblastic activities, and plasma calcium levels were measured. In an in vitro study, then, both osteoclastic and osteoblastic activities as well as each marker mRNA expression were examined. At 2 days, scale osteoclastic activity in PCB (118)-injected goldfish increased significantly, while osteoblastic activity did not change significantly. Corresponding to osteoclastic activity, plasma calcium levels increased significantly at 2 days after PCB (118) administration. Osteoclastic activation also occurred in the marker enzyme activities and mRNA expressions in vitro. Thus, we conclude that PCB (118) disrupts bone metabolism in goldfish both in vivo and in vitro experiments.
Assuntos
Osteoclastos/fisiologia , Bifenilos Policlorados/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Reabsorção Óssea , Carpa Dourada/metabolismo , Carpa Dourada/fisiologia , Osteoblastos , Osteoclastos/efeitos dos fármacos , Bifenilos Policlorados/metabolismo , Poluentes Químicos da Água/metabolismoRESUMO
In male Japanese quail, crowing behavior is considered to be strictly androgen-dependent. It was previously shown that in chicks, treatment with either testosterone or 5alpha-dihydrotestosterone (5alpha-DHT; a non-aromatizable androgen) induced crowing with motivation for distress calling in acutely isolated conditions. Many studies, however, have shown that the potencies of testosterone and 5alpha-DHT in activating crowing in castrated males are different. To clarify the effects of androgenic and estrogenic actions on the production of crows and distress calls, we injected quail daily from 11 to 42 days after hatching (Day 11 to 42) with testosterone propionate (TP), 5alpha-DHT, estradiol benzoate (EB) or vehicle and examined their calling behaviors both in a recording chamber (acutely isolated conditions) and in their home-cages (well-acclimated conditions). Both TP- and 5alpha-DHT-treated birds began to crow by Day 13 when isolated in the recording chamber. The TP-treated birds, however, crowed less frequently than 5alpha-DHT-treated ones. This, combined with the observations that distress calling was strongly inhibited in EB-treated birds, suggests that estrogen converted from testosterone may inhibit the motivation for distress calling. On the other hand, after chronic treatment of TP, but not of 5alpha-DHT, birds began to crow intensely in their home-cages earlier than vehicle treated controls, suggesting that estrogen is needed to initiate crowing behavior in sexually active males. Taken together, it is suggested that estrogenic actions affect the motivation underlying vocal behaviors, while the androgenic action is indispensable in generating crowing.