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J Balthazart

Publications and source records attributed to J Balthazart.

At least 73 records · Page 4Linked to original sources
PubMed1999

Performance of appetitive or consummatory components of male sexual behavior is mediated by different brain areas: a 2-deoxyglucose autoradiographic study.

The in vivo autoradiographic deoxyglucose method was used to identify the functional brain circuits that are involved in the performance of appetitive and consummatory components of male sexual behavior in Japanese quail (Coturnix japonica). Two groups of castrated, testosterone-treated male quail were trained during 12 sessions to associate the view of a female behind a window with the opportunity to interact freely and to copulate with her. They developed, as a consequence, a social proximity response (staying close and looking through the window providing a view of the female) that has been used in previous experiments to measure appetitive sexual behavior. A third control group (also castrated and treated with testosterone) was allowed to view the female but not to copulate with her and therefore did not develop this proximity response. 2-14C-deoxyglucose was then injected i.p. to these birds and they were allowed to either copulate freely with a female (consummatory sexual behavior group) or express the social proximity response (appetitive sexual behavior group). The control group was provided a view of the female but these birds, although they were exposed to the same stimuli as birds in the appetitive group, did not express the social proximity response because they had never learned the association with the opportunity to copulate. Birds were killed 45 min after the deoxyglucose injection and their brains were processed for autoradiography. Densitometric analyses of the autoradiograms revealed that the expression of appetitive or consummatory aspects of male sexual behavior was associated with significant increases by comparison with the control group in the deoxyglucose incorporation in the nucleus mesencephalicus lateralis, pars dorsalis and in the nucleus leminsci lateralis. In addition, an increase in the deoxyglucose incorporation was specifically observed in the paleostriatum primitivum, rostral preoptic area, nucleus intercollicularis, nucleus interpeduncularis and third nerve but a decrease was observed in the dorsomedial part of the hippocampus and in the nucleus nervi oculomotori in birds of the consummatory sexual behavior group by comparison with controls. By contrast, in the appetitive sexual behavior group, significant increases in deoxyglucose incorporation were observed in two telencephalic areas, the intermediate hyperstriatum ventrale and neostriatum caudolaterale by comparison with the controls, but decreases were detected in the stratum griseum et fibrosum superficiale of optic tectum by comparison with the consummatory behavior group. These studies demonstrate that the performance of appetitive or consummatory components of male sexual behavior affects in a specific manner the deoxyglucose uptake and accumulation in specific regions of the quail brain. Changes in metabolic activity were observed in steroid-sensitive areas, in auditory, visual and vocal brain regions, and in brain nuclei related to motor behavior but also in association telencephalic and limbic structures. These changes in oxidative metabolism overlap to some extent with metabolic changes as revealed by immunocytochemistry for the immediate early gene products Fos and Zenk, but many specific reactions are also detected indicating that these techniques are not necessarily redundant and, together, they can provide a more complete picture of the brain circuits that are implicated in the control and performance of complex behaviors.

Animals↗
PubMed1999

Effects of sexual interactions with a male on fos-like immunoreactivity in the female quail brain.

Sexual interactions can cause changes in plasma hormone levels and activate immediate early genes within the mammalian brain. There are marked anatomical differences between the regions activated that relate directly to the sexual specific behaviour and neuroendocrinology of each sex. The aim of this study was to determine if such a sexual dimorphism exists in birds by examining the brain regions stimulated in adult virgin female Japanese quail (Coturnix japonica) during sexual behaviour and comparing this to previously reported data concerning males. Female quail were allowed to freely interact with adult males and both female and male sexual behaviour was recorded. Contrary to previous findings in male quail, no significant induction of Fos-like immunoreactive (FLI) cells was observed following sexual interactions in the preoptic area of females; this area is fundamentally involved in the control of male-type copulatory behaviour. Sexual interactions significantly induced FLI cells in the hyperstriatum ventrale, the part of the archistriatum just lateral to the anterior commissure, and the nucleus intercollicularis. Moreover, prominent activation was detected throughout most of the ventromedial nucleus of the hypothalamus, a region reported to be rich in oestrogen receptors. FLI induction was not a consequence of sexual behaviour induced changes in luteinizing hormone (LH) as plasma LH levels were unaltered. Instead, brain activation must be a consequence of copulation-associated somatosensory inputs or direct stimuli originating from the male. Male quail, like the majority of other birds, lack an intromittant organ (penis) so that the somatosensory inputs to the female are rather different from those in mammals; the precise nature of these inputs is yet to be determined.

Animals↗
PubMed1999

Steroid sensitive sites in the avian brain: does the distribution of the estrogen receptor alpha and beta types provide insight into their function?

Studies in avian species have often been useful in elucidating basic concepts relevant to the regulation of reproductive behaviors by sex steroid hormones. Once a link between a steroid hormone and a behavioral response has been established, one can use the localization of steroid hormone receptors in the brain to facilitate the identification of neural circuits that control behavior. The recent identification of a second type of estrogen receptor called estrogen receptor beta or ERbeta has raised new issues about the action of steroid hormones in the brain. A hypothesis has been proposed by Kuiper et al. [1998] based on studies in mammalian species suggesting that ERalpha (the name given to the ER that was previously described) is important for reproduction while ERbeta is more important for non-reproductive functions. In this paper we apply this hypothesis more generally by examining possible functions of ERbeta in avian species. We have initiated studies of the ERbeta in the brain of two avian species, the Japanese quail (Coturnix japonica) and the European starling (Sturnus vulgaris). ERbeta was cloned in both species and the mRNA for this receptor type was localized in the brain employing in situ hybridization histochemistry methods. In both species ERbeta was found to be diffusely present in telencephalic areas consistent with a role for this receptor subtype in cognitive functions. However, ERbeta mRNA was also found in many brain areas that are traditionally thought to be important in the regulation of reproductive functions such as the preoptic region, the bed nucleus of the stria terminalis and the nucleus taeniae. Of the two receptor types, only mRNA for ERalpha was observed in the telencephalic vocal control nucleus HVc of male starlings. Steroid receptors in this nucleus are thought to be an example of an evolutionary specialization that has evolved to coordinate the production of courtship vocalizations with other aspects of reproduction. The lack of ERbeta mRNA expression in HVc is consistent with the hypothesis that ERalpha is preferentially involved in reproductive behaviors while ERbeta is involved in the steroid regulation of other neural functions. However, the widespread occurrence of ERbeta in other nuclei involved in reproductive function suggests that one must be cautious about the general applicability of the above hypothesis until more is known about ERbeta function in these other nuclei.

Animals↗
PubMed1999

Androgen receptor, estrogen receptor alpha, and estrogen receptor beta show distinct patterns of expression in forebrain song control nuclei of European starlings.

In songbirds, singing behavior is controlled by a discrete network of interconnected brain nuclei known collectively as the song control system. Both the development of this system and the expression of singing behavior in adulthood are strongly influenced by sex steroid hormones. Although both androgenic and estrogenic steroids have effects, androgen receptors (AR) are more abundantly and widely expressed in song nuclei than are estrogen receptors (ER alpha). The recent cloning of a second form of the estrogen receptor in mammals, ER beta, raises the possibility that a second receptor subtype is present in songbirds and that estrogenic effects in the song system may be mediated via ER beta. We therefore cloned the ER beta complementary DNA (cDNA) from a European starling preoptic area-hypothalamic cDNA library and used in situ hybridization histochemistry to examine its expression in forebrain song nuclei, relative to the expression of AR and ER alpha messenger RNA (mRNA), in the adjacent brain sections. The starling ER beta cDNA has an open reading frame of 1662-bp, predicted to encode a protein of 554 amino acids. This protein shares greater than 70% sequence identity with ER beta in other species. We report that starling ER beta is expressed in a variety of tissues, including brain, pituitary, skeletal muscle, liver, adrenal, kidney, intestine, and ovary. Similar to reports in other songbird species, we detected AR mRNA-containing cells in several song control nuclei, including the high vocal center (HVc), the medial and lateral portions of the magnocellular nucleus of the anterior neostriatum, and the robust nucleus of the archistriatum. We detected ER alpha expression in the medial portion of HVc (also called paraHVc) and along the medial border of the caudal neostriatum. ER beta was not expressed in HVc, in the medial and lateral portions of the magnocellular nucleus of the anterior neostriatum, in the robust nucleus of the archistriatum, or in area X. In contrast, ER beta mRNA-containing cells were detected in the caudomedial neostriatum and medial preoptic area in a pattern reminiscent of P450 aromatase expression in the same brain regions in other songbirds. These data suggest that estrogenic effects on the song system are not mediated via ER beta-producing cells within song nuclei. Nonetheless, the overlapping expression of ER beta- and aromatase-producing cells in the caudomedial neostriatum suggests that locally synthesized estrogens may act via ER beta, in addition to ER alpha, to mediate seasonal or developmental effects on nearby song nuclei (e.g. HVc).

Amino Acid Sequence↗
PubMed1998

Effects of brain testosterone implants on appetitive and consummatory components of male sexual behavior in Japanese quail.

Aromatization of testosterone (T) into an estrogen is necessary for the activation of consummatory and appetitive sexual behavior in male Japanese quail. T action within the medial preoptic nucleus (POM) is necessary and sufficient to activate consummatory behavior, and some evidence suggests that POM might be involved in the control of appetitive behavior, but other brain regions, such as the bed nucleus of the stria terminalis (BST), an area that contains a dense population of aromatase-immunoreactive neurons, are also likely to be involved. This study was performed to assess the effects of stereotaxic T implants targeting either the POM or the BST on the activation of both components of sexual behavior in castrated male quail. Appetitive sexual behavior was measured by an acquired social proximity response in which a male will approach a window providing visual access to a female after the window has been repeatedly paired with physical access to a female and the possibility to freely interact with her. Rhythmic cloacal sphincter movements that are produced by the male when given visual access to a female were used as another measure of appetitive sexual behavior that does not appear to depend on sexual learning. The experiments confirmed that copulation is necessary for males to develop the social proximity response that is used to measure the appetitive sexual behavior. T implants in the POM activated both components of sexual behavior, suggesting that these components cannot be completely dissociated. In contrast, T implants located within the BST did not affect either component, but because implants in the BST did not activate copulatory behavior, these results do not preclude a role for BST in the expression of a previously acquired appetitive sexual behavior.

Analysis of Variance↗
PubMed1998

Partial cloning and distribution of estrogen receptor beta in the avian brain.

A partial estrogen receptor beta (ER-beta) cDNA was isolated from testicular quail RNA by RT-PCR with degenerate primers specific to the rat ER-beta sequence. A high expression of ER-beta was demonstrated by RT-PCR in the telencephalon, diencephalon, pituitary, testis and kidneys of male quail but little or no expression was detected in the cerebellum, pectoral muscle and adrenal gland. In situ hybridization with a 35S-labelled oligoprobe in sections through the preoptic area-rostral hypothalamus identified high expression in the medial preoptic nucleus, bed nucleus striae terminalis and nucleus taeniae. These data demonstrate the presence of an ER-beta in brain areas implicated in the control of reproduction in a non-mammalian species.

Amino Acid Sequence↗
PubMed1998

Appetitive and consummatory male sexual behavior in Japanese quail are differentially regulated by subregions of the preoptic medial nucleus.

Central testosterone aromatization is required for the activation of both appetitive (ASB) and consummatory (CSB) male sexual behavior in Japanese quail. There are two major clusters of aromatase immunoreactive (ARO-ir) cells in the rostral forebrain; these outline the nucleus preopticus medialis (POM) and the nucleus striae terminalis (BST). We investigated the role of these nuclei in the regulation of ASB and CSB. Appetitive male sexual behavior was measured with the use of a learned social proximity procedure that quantified the time spent by a male in front of a window with a view of a female who was subsequently released into the cage, providing an opportunity for CSB. Males first acquired the response and then received bilateral electrolytic lesions aimed at the POM or BST, followed by retesting for ASB and CSB. Brain sections were stained for ARO-ir, and lesions to the two ARO-ir cell groups were quantitatively characterized. Lesions damaging the POM completely abolished CSB and also significantly decreased ASB. Lesions of the rostral BST had no effect on ASB, but moderately decreased CSB. Detailed anatomical analysis revealed that lesions of a subdivision of the POM just rostral to the anterior commissure specifically impair CSB, whereas lesions that are more rostral to this subdivision induce a severe deficit in ASB. These data indicate that different subregions of the POM regulate ASB and CSB in a somewhat independent manner, whereas the BST is only important in the regulation of CSB.

Animals↗
PubMed1998

Anatomical and neurochemical definition of the nucleus of the stria terminalis in Japanese quail (Coturnix japonica).

This study in birds provides anatomical, immunohistochemical, and hodological data on a prosencephalic region in which the nomenclature is still a matter of discussion. In quail, this region is located just dorsal to the anterior commissure and extends from the level of the medial part of the preoptic area at its most rostral end to the caudal aspects of the nucleus preopticus medialis. At this caudal level, it reaches its maximal elongation and extends from the ventral tip of the lateral ventricles to the dorsolateral aspects of the paraventricular nucleus. This area contains aromatase-immunoreactive cells and a sexually dimorphic population of small, vasotocinergic neurons. The Nissl staining of adjacent sections revealed the presence of a cluster of intensely stained cells outlining the same region delineated by the vasotocin-immunoreactive structures. Cytoarchitectonic, immunohistochemical, and in situ hybridization data support the notion that this area is similar and is probably homologous to the medial part of the nucleus of the stria terminalis of the mammalian brain. The present data provide a clear definition of this nucleus in quail: They show for the first time the presence of sexually dimorphic vasotocinergic neurons in this region of the quail brain and provide the first detailed description of this region in an avian species.

Animals↗
PubMed1998

Non invasive in vivo anatomical studies of the oscine brain by high resolution MRI microscopy.

We describe in this paper an in vivo Magnetic Resonance Imaging (MRI) procedure that allows one to obtain three-dimensional high quality images of the entire brain of small passerine birds such as the canary with a slice thickness of 58 micron and an image resolution of 78 microns. This imaging procedure was completed in 70 min on anaesthetised birds that later recovered uneventfully and could be reused for subsequent additional imaging. To illustrate the high resolution and anatomical detail that can be achieved, examples of coronal images through the entire hypothalamus are provided in the same sectioning plane as the previously published canary brain atlas. The data set can be used to create sections in any desired plane and the entire data set can be viewed from any point of view in a volume rendered image. This provides a useful tool in understanding the three-dimensional organisation of the brain. Similar procedures can also be applied on fixed brains and might allow an even better anatomical resolution of images because time constrains no longer limit the duration of image acquisition. The non-invasive MRI technique enables to study neuroanatomical features with a high resolution and without killing the animal subjects so that measures can be obtained in a same individual both before and after an experimental treatment.

Animals↗
PubMed1998

Anatomical relationships between aromatase and tyrosine hydroxylase in the quail brain: double-label immunocytochemical studies.

The activation of male sexual behavior in Japanese quail (Coturnix japonica) requires the transformation of testosterone to 17beta-estradiol by the enzyme aromatase (estrogen synthetase). There are prominent sex differences in aromatase activity that may be regulated in part by sex differences in catecholaminergic activity. In this study, we investigate, with double-label immunocytochemistry methods, the anatomical relationship between the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH) and aromatase (ARO) in the quail brain. The immunoreactivity observed for each antigen generally matched the previously described distribution. One exception is the observation that cells weakly labeled for aromatase were found widely distributed throughout the telencephalon. The presence of telencephalic aromatase was confirmed independently by radioenzymatic assays. There was an extensive overlap between the distribution of the two antigens in many brain areas. In all densely labeled aromatase-immunoreactive (ARO-ir) cell groups, including the preoptic medial nucleus, nucleus of the stria terminalis, mediobasal hypothalamus, and paleostriatum ventrale, ARO-ir cells were found in close association with TH-ir fibers. These TH-ir fibers often converged on an ARO-ir cell, and one or more TH-ir punctate structure(s) were found in close contact with nearly every densely labeled ARO-ir cell. In the telencephalon (mostly the neostriatum), all TH-ir fibers were found to be part of fiber groups that surrounded weakly immunoreactive aromatase cells. The few cells exhibiting an intracellular colocalization were detected in the anteroventral periventricular nucleus. These results are consistent with the hypothesis that catecholaminergic inputs regulate brain aromatase.

Animals↗
PubMed1998

Organizational effects of estrogens on brain vasotocin and sexual behavior in quail.

Reproductive behavior is sexually differentiated in quail: The male-typical copulatory behavior is never observed in females even after treatment with high doses of testosterone (T). This sex difference in behavioral responsiveness to T is organized during the embryonic period by the exposure of female embryo to estrogens. We showed recently that the sexually dimorphic medial preoptic nucleus (POM), a structure that plays a key role in the activation of male copulatory behavior, is innervated by a dense steroid-sensitive network of vasotocin-immunoreactive (VT-ir) fibers in male quail This innervation is almost completely absent in the female POM and is not induced by a chronic treatment with T, suggesting that this neurochemical difference could be organizational in nature. This idea was tested by injecting fertilized quail eggs of both sexes on day 9 of incubation with either estradiol benzoate (EB) (25 microg, a treatment that suppresses the capacity to show copulatory behavior in adulthood) or the aromatase inhibitor R76713 (10 microg, a treatment that makes adult females behaviorally responsive to T), or with the solvents as a control (C). At 3 weeks posthatch, all subjects were gonadectomized and later implanted with Silastic capsules filled with T. Two weeks later, all birds were perfused and brain sections were processed for VT immunocytochemistry. Despite the similarity of the adult endocrine conditions of the subjects (all were gonadectomized and treated with T Silastic implants providing the same plasma level of steroid to all subjects), major qualitative differences were observed in the density of VT-ir structures in the POM of the different groups. Dense immunoreactive structures (fibers and a few cells) were observed in the POM of C males but not females; EB males had completely lost this immunoreactivity (and lost the capacity to display copulatory behavior); and, conversely, R76713 females displayed a male-typical VT-ir system in the nucleus (and also high levels of copulatory behavior). Similar changes in immunoreactivity were seen in the nucleus of the stria terminalis and in the lateral septum (VT-ir fibers only in this case) but not in the magnocellular vasotocinergic system. These neurochemical changes closely parallel the effects of the embryonic treatments on male copulatory behavior. The vasotocinergic system of the POM can therefore be considered an accurate marker of the sexual differentiation of brain circuits mediating this behavior.

Analysis of Variance↗
PubMed1998

Neuroanatomical distribution and variations across the reproductive cycle of aromatase activity and aromatase-immunoreactive cells in the pied flycatcher (Ficedula hypoleuca).

The anatomical distribution and seasonal variations in aromatase activity and in the number of aromatase-immunoreactive cells were studied in the brain of free-living male pied flycatchers (Ficedula hypoleuca). A high aromatase activity was detected in the telencephalon and diencephalon but low to negligible levels were present in the optic lobes, cerebellum, and brain stem. In the diencephalon, most aromatase-immunoreactive cells were confined to three nuclei implicated in the control of reproductive behaviors: the medial preoptic nucleus, the nucleus of the stria terminalis, and the ventromedial nucleus of the hypothalamus. In the telencephalon, the immunopositive cells were clustered in the medial part of the neostriatum and in the hippocampus as previously described in another songbird species, the zebra finch. No immunoreactive cells could be observed in the song control nuclei. A marked drop in aromatase activity was detected in the anterior and posterior diencephalon in the early summer when the behavior of the birds had switched from defending a territory to helping the female in feeding the nestlings. This enzymatic change is presumably controlled by the drop in plasma testosterone levels observed at that stage of the reproductive cycle. No change in enzyme activity, however, was seen at that time in other brain areas. The number of aromatase-immunoreactive cells also decreased at that time in the caudal part of the medial preoptic nucleus but not in the ventromedial nucleus of the hypothalamus (an increase was even observed), suggesting that differential mechanisms control the enzyme concentration and enzyme activity in the hypothalamus. Taken together, these data suggest that changes in diencephalic aromatase activity contribute to the control of seasonal variations in reproductive behavior of male pied flycatchers but the role of the telencephalic aromatase in the control of behavior remains unclear at present.

Animals↗
PubMed1998

Imaging birds in a bird cage: in-vivo FSE 3D MRI of bird brain.

An in-vivo magnetic resonance imaging (MRI) procedure is described that allows one to obtain three-dimensional high quality images of the entire brain of small birds such as the canary (20 g) and the starling (75 g) with an image resolution of 0.1 mm (58-113 microm, dependent on the size of the imaged bird). The entire imaging procedure took about 2 h after which the birds recovered from anaesthesia uneventfully and could be reused for subsequent additional imaging. This non invasive MRI technique enables to correlate brain measures with behavioural or physiological data that are dynamic in nature and could permit significant progress for bird neurological research.

Animals↗
PubMed1998

New insights into the regulation and function of brain estrogen synthase (aromatase).

In the brain, conversion of androgens into estrogens by the enzyme aromatase (estrogen synthase) is a key mechanism by which testosterone regulates many physiological and behavioral processes, including the activation of male sexual behavior, brain sexual differentiation and negative feedback effects of steroid hormones on gonadotropin secretion. Studies on the distribution and regulation of brain aromatase have led to a new perspective on the control and function of this enzyme. A growing body of evidence indicates that the estrogen regulation of aromatase is, at least in part, trans-synaptic. Afferent catecholamine pathways appear to regulate aromatase activity in some brain areas and thereby provide a way for environmental cues to modulate this enzyme. The localization of aromatase in pre-synaptic boutons suggests possible roles for estrogens at the synapse.

Animals↗
PubMed1998

Distribution and effects of testosterone on aromatase mRNA in the quail forebrain: a non-radioactive in situ hybridization study.

A number of studies have been devoted to the analysis of the anatomical distribution, control by steroids and functional significance of aromatase (the enzyme metabolizing testosterone into 17beta-estradiol) in the quail brain. In particular, the sexually dimorphic nucleus preopticus medialis has been the main focus of investigation because testosterone aromatization in this structure mediates the activation of male sexual behavior and aromatase activity is itself testosterone-dependent in this nucleus. No information on the anatomical distribution of aromatase gene expression is, however, available so far in this avian species. In the present study we applied a non-radioactive in situ hybridization technique to describe the distribution of aromatase mRNA containing neurons in the quail prosencephalon. We also analyzed, at a neuronal level of resolution, the induction by testosterone of this mRNA in the medial preoptic nucleus. Dense clusters of aromatase gene expressing neurons were observed within the medial preoptic nucleus, the nucleus of the stria terminalis, the ventro-medial hypothalamus and the tuberal region. Scattered neurons expressing lower levels of aromatase mRNA were also found in the dorsal thalamic area and central gray. The specificity of the staining was confirmed by demonstrating the absence of signal in sections that had been hybridized with a sense probe. Moreover, the distribution of the aromatase mRNA containing cells completely overlapped with the distribution of the aromatase-immunoreactive cells. Aromatase-mRNA expression was controlled by testosterone (or its metabolites) in the entire medial preoptic nucleus. Castration resulted in a decrease in the number of aromatase mRNA-containing cells and this effect was totally reversed by testosterone treatment. These data further support the idea that testosterone regulates the rate of its own aromatization by modulating the expression of aromatase rather than by acting at a post transcriptional level.

Animals↗
PubMed1998

Pharmacological characterization, anatomical distribution and sex differences of the non-NMDA excitatory amino acid receptors in the quail brain as identified by CNQX binding.

The distribution of non-N-methyl-D-aspartate binding sites was studied in coronal and sagittal sections through the brain of adult Japanese quail by quantitative autoradiography, using tritiated 6-cyano-7-nitroquinoxaline-2,3-dione as a radioligand. Saturation binding experiments were, in addition, carried out in areas showing high levels of binding (cerebellar molecular layer, nucleus anterior medialis and nucleus infundibularis) and demonstrated that the binding of tritiated ligand was specific and saturable. Competition studies with alpha-amino-3-hydroxy-methyl-4-isoxazole propionic acid and kainic acid indicated that kainic acid strongly inhibited ligand binding in all brain areas. alpha-Amino-3-hydroxy-methyl-4-isoxazole propionic acid was only a weak inhibitor in the hypothalamic nuclei whereas in the cerebellar molecular layer both high and low affinity inhibitions were detected. The highest binding levels of tritiated ligand were observed in the molecular layer of the cerebellum. Very high levels of binding were detected in various preoptic/hypothalamic sites including the nucleus suprachiasmaticus pars medialis, nucleus anterior medialis hypothalami, nucleus infundibularis, nucleus mammillaris medialis, nucleus posteromediale hypothalami and nucleus hypothalami ventromedialis. High levels of binding were also detected in the bulbus olfactorius, bed nucleus commissuralis anterior, bed nucleus commissuralis pallii, nucleus accumbens, bed nucleus striae terminalis and nucleus interpeduncularis. In the preoptic area/hypothalamus, high levels of binding were clearly present in all areas that contain gonadotropin releasing hormone cells or fibers. In the pons and mesencephalon, moderate levels of binding were associated with catecholaminergic areas such as the area ventralis tegmentalis (area ventralis of Tsai) and the locus coeruleus. Saturation analysis demonstrated the presence of a higher number of binding sites in females than in males in the cerebellar molecular layer, nucleus infundibularis and nucleus anterior medialis. This latter difference was confirmed in the one point assays that also identified higher levels of specific binding in the nucleus suprachiasmaticus pars medialis of males as compared with females. These anatomical data suggest a possible implication of non-N-methyl-D-aspartate receptors in the synthesis and/or release of both gonadotropin releasing hormone and catecholaminergic neurotransmitters that should now be tested by pharmacological experiments.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1998

Systemic and intracerebroventricular injections of vasotocin inhibit appetitive and consummatory components of male sexual behavior in Japanese quail.

The authors investigated the behavioral actions of vasotocin (VT) in castrated testosterone-treated male Japanese quail. The appetitive and consummatory components of sexual behavior as well as the occurrence frequency of crows were inhibited, in a dose-dependent manner, by injections of VT. The authors observed opposite effects after injection of the V1 receptor antagonist, dPTyr(Me)AVP. Lower doses of VT were more active after central than after systemic injection, and effects of systemic injections of VT were blocked by a central injection of dPTyr(Me)AVP. The behavioral inhibition was associated with a modified diuresis after systemic but not central injection. These results provide direct evidence that VT affects male sexual behavior in quail by a direct action on the brain independent of its peripheral action on diuresis.

Animals↗