Altered brain metabolism of testosterone is correlated with reproductive decline in aging quail

In aging quail, an increasing proportion of males show no sexual behavior. A decrease in the mean size of the tests, cloacal gland, and sternotracheal muscles is also observed. In both sexually active and inactive males, plasma testosterone decreases with age but more so in inactive birds. The behavioral and morphological changes observed during aging are correlated with shifts in the intracellular testosterone metabolism resulting in a change in the ratio of active versus inactive metabolites. In the hypothalamus there is a steady decrease with age of 5 beta-reductase activity in all birds and an increase in 5 alpha-reductase activity only in the birds which remain sexually active. In the cloacal gland, the 5 beta-reductase activity markedly increases with age but more so in the birds which become sexually inactive. These data support the notion that the effects of testosterone are controlled by enzymatic shifts which could modulate the sensitivity to the hormone at the cellular level.     

The role of testosterone in the organization, maintenance and activation of pup-killing behavior in the male rat.

When placed together with a group of newborn pups, an adult male rat will usually kill and devour the pups whereas a female usually will not. The present experiment was designed to further examine the role of testosterone in the development and exhibition of this sexually dimorphic behavior by controlling the presence or absence of testosterone during three age spans: Days 2–30, 31–90, and 91–120. The results indicate that it is meaningful to use the developmental concepts of organization and activation with regard to the hormonal control of pup-killing behavior, but exposure to testosterone between organization and activation (i.e., maintenance) was not necessary.     

Iron metabolism in iron-deficient male quail

1. Male quails submitted 20 and 120 days to a low iron diet (7 ppm) were compared to female laying quails, exposed for 30 days to the same low iron regime, in order to compare the response of the iron metabolic control under a single (erythropoiesis) or a doubled (erythropoiesis and egg formation) iron demand. 2. Iron deposit in storage organs, the classical hematology and the intestinal iron absorption were analyzed in these animals. 3. In males, after 120 days, the iron deposits were reduced 50 and 75%, but hematological values (hematocrit and hemoglobin concentration) were normal, although in laying quails, after 30 days, an anemic condition was evident in both blood parameters and iron deposits, provoking an iron deficient erythropoiesis. 4. The enhancement of the intestinal iron uptake, confirms the anemic character of these birds.     

Threonine metabolism in Japanese quail liver

Summary. In general, threonine is metabolized by reaction catalyzed by threonine-3-dehydrogenase (TDH), threonine dehydratase (TH) or threonine aldolase (TA). The activities of these three enzymes were compared in the liver of Japanese quails and rats. The animals were fed a standard or threonine rich-diet, or fasted for 3 days. The specific activity of TDH in the liver from quail fed a standard diet was 11 times higher than that in the liver from rats fed a standard diet. The TDH activities in the livers of the fasting and 5% threonine-rich diet groups of quail were 3 and 2 times higher than those in the livers from quail fed the standard diet, respectively. The TH activity in the liver of rats fed a standard diet was 14 times higher than that in the liver of quail fed a standard diet. The TH activity in the rat liver after fasting was 2.3 times higher than that of the standard diet control. The activity of TA in the livers of rat and quail were so low that its role in threonine metabolism in both animals seemed to be negligible. These results suggest that threonine is a ketogenic amino acid in the quail liver, while it is a glucogenic in the rat liver.     

Influence of castration and testosterone on pineal multi-unit activity in quail.

Pineal multiple unit electrical activity was recorded in unanaesthetized quail maintained under a short or long daily photoperiod. Both spontaneous and flash-induced multiple unit firing were recorded in intact, castrated or superior cervical ganglionectomized birds. The effects of testosterone administration were tested in each experimental group. 10 Whereas orchidectomy led to a substantial rise in pineal multi-unit activity (MUA), testosterone propionate injection resulted in a markedly decreased MUA in castrates. A smaller decrease in MUA was caused by androgen treatment in intact or ganglionectomized birds. Androgen treatment of controls and ganglionectomized quail was not so effective in reducing pineal activity as was lengthening the photoperiod from 6L-18D to 18L-6D. 20 Repetitive photic stimulations resulted in a significant suppression of pineal MUA in all intact, castrated and ganglionectomized quail, whether or not testosterone was administered.     

Specific activation of estrogen receptor alpha and beta enhances male sexual behavior and neuroplasticity in male Japanese quail

Two subtypes of estrogen receptors (ER), ERα and ERβ, have been identified in humans and numerous vertebrates, including the Japanese quail. We investigated in this species the specific role(s) of each receptor in the activation of male sexual behavior and the underlying estrogen-dependent neural plasticity. Castrated male Japanese quail received empty (CX) or testosterone-filled (T) implants or were daily injected with the ER general agonist diethylstilbestrol (DES), the ERα-specific agonist PPT, the ERβ-specific agonist DPN or the vehicle, propylene glycol. Three days after receiving the first treatment, subjects were alternatively tested for appetitive (rhythmic cloacal sphincter movements, RCSM) and consummatory aspects (copulatory behavior) of male sexual behavior. 24 hours after the last behavioral testing, brains were collected and analyzed for aromatase expression and vasotocinergic innervation in the medial preoptic nucleus. The expression of RCSM was activated by T and to a lesser extent by DES and PPT but not by the ERβagonist DPN. In parallel, T fully restored the complete sequence of copulation, DES was partially active and the specific activation of ERα or ERβ only resulted in a very low frequency of mount attempts in few subjects. T increased the volume of the medial preoptic nucleus as measured by the dense cluster of aromatase-immunoreactive cells and the density of the vasotocinergic innervation within this nucleus. DES had only a weak action on vasotocinergic fibers and the two specific ER agonists did not affect these neural responses. Simultaneous activation of both receptors or treatments with higher doses may be required to fully activate sexual behavior and the associated neurochemical events.     

Cocaine-induced sensitization correlates with testosterone in male Japanese quail but not with estradiol in female Japanese quail

Research has indicated that gonadal hormones may mediate behavioral and biological responses to cocaine. Estrogen, in particular, has been shown to increase behavioral responding to cocaine in female rats relative to male rats. The current study investigated the effect of cocaine on locomotor activity and hormonal correlates in male and female Japanese quail (Coturnix japonica). In Japanese quail, circulating hormone levels can be manipulated without surgical alterations via modifying the photoperiod. Male and female quail were housed on either 8L:16D (light:dark) or 16L:8D (light:dark) cycle for 21 days. Blood samples were taken prior to the beginning of the experiment and assays were performed to determine the levels of testosterone (T) and estradiol (E2). Quail were given injections of saline or cocaine (10 or 20 mg/kg) once a day for 10 days. Immediately after each injection, birds were placed in open field arenas and distance traveled was measured for 30 min. Results showed that male quail housed under long-light conditions exhibited cocaine-induced sensitization to 10 mg/kg cocaine which was correlated with the high levels of plasma T. Female quail housed under short-light conditions demonstrated sensitization to 10 mg/kg cocaine, but this was not correlated with the levels of plasma E2. The current findings suggest that cocaine-induced locomotor activity was associated with T in males but not with E2 in females.     

Agonistic behavior and neurochemistry in grouped Japanese quail

Aggressive behavior and whole brain neurochemistry were measured in stable and unstable pairs of male Coturnix coturnix japonica. Aggressive pecking peaked on day 5 of the daily regrouping regime and returned to a basal level on day 14. Aggressive behavior was associated with increased brain norepinephrine (NE), dopamine (DA), and acetylcholinesterase (AChE) in unstable pairs. Habituation (12-15 days) and DA response to daily regrouping and inanition were inversely related in unstable and stable pairs respectively. Normal whole brain NE increases were attenuated in unstable pairs.     

Male sex behavior and testosterone concentrations in gilts administered testosterone propionate

Two gilts were administered testosterone propionate and their subsequent plasma testosterone concentrations and male sex behavior were recorded. These were compared to testosterone concentrations and male sex behavior in boars. Testosterone propionate (75 mg) was administered to the gilts every other day for 20 days (induction scheme) and every 10 days there-after (maintenance scheme). Concentrations of testosterone in plasma were elevated to concentrations detected in the boars during the induction scheme. During the maintenance scheme, concentrations of testosterone appeared to be lower than in boars. At 20, 30 and 40 days following the first injection, sniffing, nosing and mating song behaviors were exhibited by the testosterone treated gilts similar in frequency to the boars. Mounting behavior was first detected 30 days following the first testosterone propionate injection, and by day 40, the frequency of mounting was greater than observed in boars.     

Hormonal differentiation of sexual behavior in Japanese quail

The effect of hormones on the development of Japanese quail during the postembryonic period was examined. First, subcutaneous implants of estradiol monobenzoate (EB) and testosterone propionate (TP) were implanted 6–12 hr after hatching. EB and TP had no effect on the differentiation of sexual behavior in genetic males or females. However, EB had marked feminizing effects on plumage in genetic males. Second, the role of gonadal hormones during development was examined by gonadectomizing males and females 6–12 hr after hatching and treating them intramuscularly with EB or TP as adults. EB-treated adult females displayed sexual behavior typical of the genetic female and developed female plumage. A significant proportion of TP-treated females (57%) displayed male sexual behavior patterns. Cloacal gland development and male-type vocalizations were induced. EB-treated males displayed either male or female sexual patterns depending on the stimulus conditions. Third, to test whether bisexuality in gonadectomized males and females is maintained despite steroid treatment and expression of sexual behavior in adulthood, gonadectomized quail which were originally treated with EB received TP and vice versa. The results indicate that in the absence of gonadal hormones after hatching female quail remain bisexual until exposed to estrogen, whereas gonadectomized male quail retain behavioral bisexuality irrespective of prior estrogen or androgen exposure.     

Distribution and metabolism of selenite and selenomethionine in the Japanese quail

Compared to the many studies on the physiological and toxicological effects of selenium (Se) in mammals, avian Se metabolism is still an unexplored topic. Some birds are useful as poultry for human nutrition. Moreover, birds belong to higher trophic levels in the biosphere and thus may play an important role in Se circulation in the ecosystem in the same way as mammals do. In this study, we analyzed the distribution and metabolism of Se in an experimental bird, the Japanese quail, which was fed drinking water containing sodium selenite or selenomethionine (SeMet). The highest concentration of Se was detected in the pancreas, followed by down feathers, liver, and kidneys. SeMet was more efficiently incorporated into the quail than selenite. The specific and preferable distribution of Se to the high molecular weight fraction in the serum of the quail was observed only in the SeMet-ingestion group. As in mammals, selenosugar and trimethylselenonium were the major metabolites in quail excreta. Three unknown Se metabolites were detected by HPLC-ICP-MS. Although part of the metabolic pathway of Se in the Japanese quail fed selenite and SeMet was the same as that observed in mammals, the bird also showed certain avian-specific metabolic process for Se.     

Testosterone metabolism in the uropygial gland of the quail

The metabolism of testosterone in the uropygial gland of the quail principally results in the production of 17 alpha, 5 beta derivatives. Moreover, an unusually small amount of testosterone is converted to 5 alpha-dihydrotestosterone. These results question the role played by intracellular 5 alpha-reduction in the response of the gland to testosterone stimulation.     

Vasotocinergic innervation of the septal region in the Japanese quail: sexual differences and the influence of testosterone

Summary Vasotocin (VT)-immunoreactive fibres were observed in the nuclei of the quail (Coturnix coturnix japonica) septal region. Their distribution in the nucleus septalis lateralis (SL) and the nucleus striae terminalis (nST) was sexually dimorphic: a dense network of immunoreactive fibres was seen in adult sexually stimulated males but not in females. Experimental manipulation of the hormonal environment influenced this distribution only in males. VT immunoreactivity was absent in SL and nST when male quail were exposed to a shortday photoperiod or castrated. The immunoreactivity was restored to its original level in castrated males by silastic implants of testosterone.     

Circadian ovulatory rhythms in Japanese quail: role of ocular and extraocular pacemakers

Previous studies have shown that the circadian system of Japanese quail is composed of multiple photic inputs and multiple oscillators. Among these are extraretinal photoreceptors that mediate both circadian and photoperiodic responses and circadian pacemakers in the eyes that, via neural and hormonal outputs, help to maintain rhythmicity of central circadian clocks (presumably located in the suprachiasmatic area of the hypothalamus). Furthermore, a component of the central circadian system is influenced by reproductive hormones. Under certain conditions, the circadian system of female quail can be induced to split into two circadian components: one driven by ocular pacemakers and one driven by feedback from reproductive hormones. Importantly, ovulation is either inhibited or permitted as these two oscillators (or sets of oscillators) constantly change internal phase relationships with each other, suggesting an "internal coincidence" mechanism in the control of ovulation. The oviposition patterns of quail in light-dark (LD) cycles also support an internal coincidence mechanism. The authors tested the hypothesis that the ocular pacemakers are an important component of an internal coincidence mechanism controlling ovulation by examinig the effects of blinding by complete eye removal (EX), and the effects of eye-patching, on the body temperature and oviposition patterns of quail exposed to 24-h LD cycles. They also examined the effects of EX on quail exposed to continuous light (LL) and to continuous darkness (DD). Neither EX nor eye-patching affected the oviposition patterns of birds in LD. Furthermore, robust body temperature and oviposition rhythms continued in EX birds in LL, but body temperature became arrhythmic in DD with the cessation of ovulation. The results do not show a role for ocular pacemakers in the control of ovulation, but they do support the hypotheses that (1) entrainment of the central oscillators by extraretinally perceived light is sufficient to preserve a normal ovulatory pattern in LD in the absence of the ocular pacemakers, and (2) in LL, feedback of reproductive hormones onto the central oscillators is sufficient to organize the circadian system even in the absence of the ocular pacemakers. Whether or not the ocular pacemakers are normally involved in the control of ovulation is still an open question.