Distribution of dopamine and octopamine in the central nervous system and ovary during the ovarian maturation cycle of the giant freshwater prawn, Macrobrachium rosenbergii

Dopamine (DA), octopamine (OA) and serotonin (5-HT) are the key neurotransmitters that control gonadal development in decapod crustaceans. 5-HT stimulates, while DA and OA delay gonadal development in Macrobrachium rosenbergii. In the present study, we have further investigated the distribution patterns of DA and OA in the central nervous system (CNS) and ovary during various stages of the ovarian maturation cycle of this giant freshwater prawn. DA- and OA-immunoreactive neurons and fibers were distributed extensively in several regions of the brain, subesophageal ganglion (SEG), thoracic ganglia and abdominal ganglia. In the brain, the two neurotransmitters were present in neurons of clusters 6, 7, 11, 17, and nearby neuropil regions. In the SEG, thoracic ganglia and abdominal ganglia, immunoreactive neurons and fibers were found along the midline and in several neuronal clusters around each neuropil region. Staining for DA and OA was more intense in the thoracic ganglia than in other parts of the CNS. In the ovary, DA- and OA-immunoreactivities were present at high intensity in early oocytes. The presence of DA- and OA-immunoreactivities in neural ganglia as well as ovary suggests that DA and OA may also be involved in the reproductive process, particularly ovarian development and differentiation of oocytes in this species.     

Expression of serotonin (5-HT) during CNS development of the cephalopod mollusk, Idiosepius notoides

Cephalopods are unique among mollusks in exhibiting an elaborate central nervous system (CNS) and remarkable cognitive abilities. Despite a profound knowledge of the neuroanatomy and neurotransmitter distribution in their adult CNS, little is known about the expression of neurotransmitters during cephalopod development. Here, we identify the first serotonin-immunoreactive (5-HT-ir) neurons during ontogeny and describe the establishment of the 5-HT system in the pygmy squid, Idiosepius notoides. Neurons that are located dorsally to each optic lobe are the first to express 5-HT, albeit only when the lobular neuropils are already quite elaborated. Later, 5-HT is expressed in almost all lobes, with most 5-HT-ir cell somata appearing in the subesophageal mass. Further lobes with numerous 5-HT-ir cell somata are the subvertical and posterior basal lobes and the optic and superior buccal lobes. Hatching squids possess more 5-HT-ir neurons, although the proportions between the individual brain lobes remain the same. The majority of 5-HT-ir cell somata appears to be retained in the adult CNS. The overall distribution of 5-HT-ir elements within the CNS of adult I. notoides resembles that of adult Octopus vulgaris and Sepia officinalis. The superior frontal lobe of all three species possesses few or no 5-HT-ir cell somata, whereas the superior buccal lobe comprises many cell somata. The absence of 5-HT-ir cell somata in the inferior buccal lobes of cephalopods and the buccal ganglia of gastropods may constitute immunochemical evidence of their homology. This integrative work forms the basis for future studies comparing molluscan, lophotrochozoan, ecdysozoan, and vertebrate brains.     

Existence and distribution of gonadotropin-releasing hormone-like peptides in the central nervous system and ovary of the Pacific white shrimp, <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

We used antibodies against octopus gonadotropin-releasing hormone (octGnRH) and tunicate GnRH (tGnRH-I) in order to investigate the existence and distribution of GnRH-like peptides in the central nervous system (CNS) and in the ovary during various stages of the ovarian cycle of the white shrimp, Litopenaeus vannamei. OctGnRH-immunoreactive and tGnRH-I-immunoreactive neurons and fibers were present in several regions of the supraesophageal ganglion (brain), subesophageal ganglion (SEG), thoracic ganglia, and abdominal ganglia. In the brain, both octGnRH immunoreactivity (ir) and tGnRH-I-ir were detected in neurons of clusters 6, 11, 17, and associated fibers, and the anterior medial protocerebral, posterior medial protocerebral, olfactory, and tegumentary neuropils. In the SEG and thoracic ganglia, octGnRH-immunoreactive and tGnRH-I-immunoreactive neurons and fibers were present in dorsolateral and ventromedial cell clusters and in surrounding fibers. Only immunoreactive fibers were detected in the abdominal ganglia. In the ovary, both octGnRH and tGnRH-I were detected at medium intensity in the cytoplasm of early step oocytes (Oc2) and, at high intensity, in Oc3. Furthermore, octGnRH-ir and tGnRH-I-ir were intense in follicular cells surrounding Oc2 and Oc3. The presence of GnRH-ir in the CNS and ovary indicates that GnRH-like peptides occur in the white shrimp, and that GnRHs are involved in the reproductive process, especially ovarian maturation and the differentiation of oocytes, as reported in other species.     

Three-dimensional organization of the brain and distribution of serotonin in the brain and ovary,and its effects on ovarian steroidogenesis in the giant freshwater prawn, <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis>

The giant freshwater prawn, Macrobrachium rosenbergii, is an economically important crustacean species which has also been extensively used as a model in neuroscience research. The crustacean central nervous system is a highly complex structure, especially the brain. However, little information is available on the brain structure, especially the three-dimensional organization. In this study, we demonstrated the three-dimensional structure and histology of the brain of M. rosenbergii together with the distribution of serotonin (5-HT) in the brain and ovary as well as its effects on ovarian steroidogenesis. The brain of M. rosenbergii consists of three parts: protocerebrum, deutocerebrum and tritocerebrum. Histologically, protocerebrum comprises of neuronal clusters 6–8 and prominent anterior and posterior medial protocerebral neuropils (AMPN/PMPN). The protocerebrum is connected posteriorly to the deutocerebrum which consists of neuronal clusters 9–13, medial antenna I neuropil, a paired lateral antenna I neuropils and olfactory neuropils (ON). Tritocerebrum comprises of neuronal clusters 14–17 with prominent pairs of antenna II (AnN), tegumentary and columnar neuropils (CN). All neuronal clusters are paired structures except numbers 7, 13 and 17 which are single clusters located at the median zone. These neuronal clusters and neuropils are clearly shown in three-dimensional structure of the brain. 5-HT immunoreactivity (-ir) was mostly detected in the medium-sized neurons and neuronal fibers of clusters 6/7, 8, 9, 10 and 14/15 and in many neuropils of the brain including anterior/posterior medial protocerebral neuropils (AMPN/PMPN), protocerebral tract, protocerebral bridge, central body, olfactory neuropil (ON), antennal II neuropil (Ann) and columnar neuropil (CN). In the ovary, the 5-HT-ir was light in the oocyte step 1(Oc₁) and very intense in Oc₂–Oc₄. Using an in vitro assay of an explant of mature ovary, it was shown that 5-HT was able to enhance ovarian estradiol-17β (E₂) and progesterone (P₄) secretions. We suggest that 5-HT is specifically localized in specific brain areas and ovary of this prawn and it plays a pivotal role in ovarian maturation via the induction of female sex steroid secretions, in turn these steroids may enhance vitellogenesis resulting in oocyte growth and maturation.     

The distribution of APGWamide and RFamides in the central nervous system and ovary of the giant freshwater prawn, Macrobrachium rosenbergii

Immunohistochemistry was used to identify the distribution of both APGWamide-like and RFamide-like peptides in the central nervous system (CNS) and ovary of the mature female giant freshwater prawn, Macrobrachium rosenbergii. APGWamide-like immunoreactivity (ALP-ir) was found only within the sinus gland (SG) of the eyestalk, in small- and medium-sized neurons of cluster 4, as well as their varicosed axons. RFamide-like immunoreactivity (RF-ir) was detected in neurons of all neuronal clusters of the eyestalk and CNS, except clusters 1 and 5 of the eyestalk, and dorsal clusters of the subesophageal, thoracic, and abdominal ganglia. The RF-ir was also found in all neuropils of the CNS and SG, except the lamina ganglionaris. These immunohistochemical locations of the APGWamide-like and RF-like peptides in the eyestalk indicate that these neuropeptides could modulate the release of the neurohormones in the sinus gland. The presence of RFamide-like peptides in the thoracic and abdominal ganglia suggests that it may act as a neurotransmitter which controls muscular contractions. In the ovary, RF-ir was found predominantly in late previtellogenic and early vitellogenic oocytes, and to a lesser degree in late vitellogenic oocytes. These RFs may be involved with oocyte development, but may also act with other neurohormones and/or neurotransmitters within the oocyte in an autocrine or paracrine manner.     

MnHSP90 cDNA characterization and its expression during the ovary development in oriental river prawn, <Emphasis Type="Italic">Macrobrachium nipponense</Emphasis>

Heat shock protein 90 (HSP90) is not only involved in environmental stress but also plays roles in the ovary development in some vertebrates. To understand its role in crustacean, we examined the HSP90 cDNA for the first time in the ovary and hepatopancreas of the oriental river prawn, Macrobrachium nipponense and designated this protein as MnHSP90 in this study. The MnHSP90 was cloned by the methods of degenerated oligonucleotide primers and rapid amplification of the cDNA ends (RACE). Bioinformatics analysis showed that the MnHSP90 cDNA was 2,684 bp in length, containing a 126 bp 5′ untranslated region (UTR), a 359 bp 3′ UTR, and an open reading frame (ORF) of 2,199 bp encoding a 732-amino acid polypeptide with predicted molecular mass of 84.3 KDa. Sequence alignment showed that the MnHSP90 shared 72–79% identity with other animals. Real-time quantitative PCR (qPCR) analysis demonstrated that the MnHSP90 mRNA was ubiquitously detected in all tested tissues, with the highest expression in the thoracic ganglia, the mediate in heart, muscle and intestine, and the lowest in haemocytes and gills. The MnHSP90 mRNA levels in the hepatopancreas and ovary of M. nipponense reached a maximum at the stage III (early vitellogenic stage) and stage IV (later vitellogenic stage) ovaries, respectively, and then decreased significantly in both tissues as the ovarian development proceeded. The level of MnHSP90 expression in the hepatopancreas was higher than that in the ovary when compared with in the same ovarian developmental stage. Our results indicate that MnHSP90 is involved in ovarian development in oriental river prawn and may play a regulatory role in ovary maturation.     

Ultrastructural detection of proteins, lipids and carbohydrates in oocytes of Amblyomma triste (Koch, 1844) (Acari; Ixodidae) during the vitellogenesis process

The ovary of the tick Amblyomma triste is classified as panoistic, which is characterized by the presence of oogonia without nurse and follicular cells. The present study has demonstrated that the oocytes in all developmental stages (I-IV) are attached to the ovary through a pedicel, a cellular structure that synthesizes and provides carbohydrate, lipids and proteins supplies for the oocytes during the vitellogenesis process. The lipids are deposited during all oocyte stages; they are freely distributed as observed in stages II, III and IV or they form complexes with other elements. The proteins are also deposited in all stages of the oocytes, however, in lower concentration in the stage IV. There is carbohydrate deposition from oocytes in the stage II as well as in stages III and IV. In addition, the present work has demonstrated that the oocyte yolk of A. triste has a glycolipoprotein nature and the elements are deposited in the following sequence: firstly the lipids and proteins, and finally the carbohydrates.     

Regional Heterogeneity of Nicotine Effects on Neurotransmitters in Rat Brains <Emphasis Type="Italic">in vivo</Emphasis> at Low Doses

In our recent studies on nicotine-induced changes in neurotransmitters in brain areas associated with cognitive function using a nicotine dose of 0.5 mg/kg administered subcutaneously to conscious freely moving rats, we found changes in dopamine, norepinephrine, and serotonin, and their metabolites, in the areas examined. For the present report we examined changes in these neurotransmitters following administration of lower nicotine doses, to test regional differences in nicotine response and possible threshold levels for some effects of nicotine. The doses used were 0.15 mg/kg and 0.03 mg/kg nicotine administered subcutaneously. Nicotine levels in the brain reached peak values in less than 10 min and decreased with a half-life of about 60 min (0.15 mg/kg) or 30 min (0.03 mg/kg) to values below detection limits (1 ng/g), by the later time points of the 0.03 mg/kg experiments. Nicotine-induced dopamine (DA) increase (and increase in DA metabolites) and decrease in 5-HT levels at 0.15 mg/kg were significant in the cortex, less so in the hippocampus. Norepinephrine (NE) increase at 0.15 mg/kg was much less significant than found previously at 0.5 mg/kg. At a low nicotine dose (0.03 mg/kg), the significant changes observed were a decrease in 5-HT in the hippocampus and small increases of DA and NE in the prefrontal cortex and of NE in the medial temporal cortex. In the nucleus accumbens DA, NE, and 5-HT and their metabolites in the ventral tegmental area, mostly DA and metabolites were increased. We conclude that in areas of cognitive function nicotine-induced DA changes are more concentration dependent than changes in NE or 5-HT, and that there are regional differences in neurotransmitter changes induced by nicotine, with NE changes detectable only in the cortex and 5-HT changes only in the hippocampus at a low nicotine dose, indicating significant regional variation in sensitivity to nicotine-induced neurotransmitter changes in brain areas associated with cognitive function. The decrease in 5-HT shows that nicotine also has indirect effects caused by neurotransmitters released by nicotine. The effects of low nicotine dose are more significant in areas of reward function, indicating differences in sensitivity between cognitive and reward functions.     

Dopamine and serotonin in the larval CNS of a drosophilid fly, Chymomyza costata: are they involved in the regulation of diapause?

Developmental profiles of dopamine (DA) and serotonin (5-hydroxytryptamine, 5-HT) in the larval CNS of Chymomyza costata were measured by HPLC using electrochemical detection. Larvae of two strains, wild-type (W) and nondiapause mutant (M), were maintained either under long-day (LD, inducing pupariation) or short-day (SD, inducing diapause in W-strain) photoperiods. The levels of DA ranged from 10 fmol/CNS (early 3rd instar larvae) to 60 fmol/CNS (150-day-old diapausing larvae); the range for 5-HT was from 10 fmol/CNS to 75 fmol/CNS in the same larvae. During the 3rd larval instar, which is the decisive stage for photoperiodic induction of diapause, no differences were found in DA developmental profiles between different strains or conditions. Some differences were found in 5-HT developmental profiles, but only after the end of sensitive stage, and were therefore regarded as insignificant for regulation of developmental mode. Similarly, no clear correlations between the developmental profiles of DA and 5-HT and the course of developmental changes during the maintenance and termination of a few-month-long larval diapause were observed. Furthermore, the DA and 5-HT levels in the CNS were pharmacologically manipulated by feeding the larvae with either precursors or enzyme inhibitors of DA and 5-HT biosynthesis. Although retardations of growth and development were observed, the treated larvae retained full capacity for the photoperiodic response, irrespective of the level of DA or 5-HT in their CNS. Larvae with their 5-HT depleted to trace levels survived and were capable of diapause induction, maintenance, and termination. Depletion of DA to trace levels resulted in 100% mortality. Collectively, the present study indicates that 5-HT in the CNS is dispensable for the photoperiodic response in C. costata. More information is needed to elucidate the potential role of DA.     

两种吗啡依赖大鼠模型脑内单胺神经递质水平的比较

目的通过对吗啡诱导的躯体依赖与精神依赖两种大鼠模型脑内单胺类递质水平的比较,探讨其在吗啡依赖形成中的作用。方法采用剂量递增法复制吗啡依赖大鼠模型,然后用纳洛酮催促,引起躯体戒断症状。连续给予吗啡（5mg／kg,ip）6d,引起大鼠产生显著的条件性位置偏爱效应。脑组织去甲肾上腺素（NE）、5-羟色胺（5-HT）和多巴胺（DA）含量采用荧光分光光度法测定。结果吗啡依赖大鼠催促戒断后脑内NE和5-HT水平明显升高,DA水平下降。吗啡在引起大鼠明显位置偏爱的同时,使大鼠脑内DA和5-HT水平显著升高,NE无明显改变。结论吗啡依赖的形成和戒断与脑内单胺神经递质有密切关系,吗啡依赖的躯体戒断症状与NE升高有关,而吗啡诱导的精神依赖则与脑内DA水平升高有关。     

Serotonin-immunoreactive neurons in scorpion pectine neuropils: similarities to insect and crustacean primary olfactory centres?

The pectines of scorpions are a single pair of mechano- and chemosensory appendages located ventrally behind the most posterior pair of walking legs. They are used for probing the substrate in behaviours such as prey tracking and courtship. The sensory afferents on the pectines supply large segmental neuropils with a conspicuous glomerular structure. The pectine neuropils thus bear similarities to insect and crustacean deutocerebral chemosensory centres associated with the antennae, but they also possess idiosyncratic features. One characteristic property of many insect and decapod crustacean olfactory neuropils is their innervation by single, or very few, large serotonergic (inter-) neurons. This feature, among others, has been proposed to support homology of the olfactory lobes in the two arthropod groups. A possible serotonergic innervation of the scorpion pectine neuropils has not yet been studied, despite its apparent diagnostic and functional importance. We thus examined serotonin-immunoreactivity in the pectine neuropils of Androctonus australis and Pandinus imperator. Both scorpion species yielded similar results. The periphery of the neuropil and the matrix between the glomeruli are supplied by a dense network of serotonin-immunoreactive (5-HT-ir) arborisations and varicosities, while the glomeruli themselves are mostly free of 5-HT-ir fibres. The 5-HT-ir supply of the pectine neuropils has two origins. The first is a pair of neurons on each body side, up to 30 μm in diameter and thus slightly larger than the surrounding somata. These cell bodies are and associated with the neuromeres of the genital and pectine segments. The situation is reminiscent of the 5-HT supply of insect and crustacean olfactory and antennal neuropils. The second 5-HT innervation of the pectine neuropils is from a group of some 10-20 ipsilateral neuronal somata of slightly smaller size (15-20 μm). These are part of a much larger 5-HT-ir group comprising 70-90 somata. The whole group is located more anteriorly than the single soma mentioned above, and associated with the neuromere of the last (4th) walking leg. When compared to data from other arthropods, our findings may suggest that glomerular organisation is an ancestral feature of primary chemosensory centres innervated by arthropod appendages. This idea needs further scrutiny, although supporting evidence may have been overlooked previously, due to the small size of chemosensory neuropils in walking legs and in reduced segmental appendages.     

Effects of acute 17alpha-methyltestosterone,acute 17beta-estradiol,and chronic 17alpha-methyltestosterone on dopamine,norepinephrine and serotonin levels in the pituitary,hypothalamus and telencephalon of rainbow trout (Oncorhynchus mykiss)

This study investigated: (a) the effects of acute 17alpha-methyltestosterone (MT) or 17beta-estradiol (E(2)) administration on norepinephrine (NE), dopamine (DA), serotonin (5-HT), 3,4, dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5-HIAA) contents in the hypothalamus, telencephalon and pituitary of previtellogenic female rainbow trout Oncorhynchus mykiss, and (b) the effects of chronic MT administration on the levels of these neurotransmitters in these brain regions in immature male rainbow trout. The acute administration of MT induced a significant decrease in pituitary levels of DOPAC as well as in the DOPAC/DA ratio. On the other hand, the acute administration of E(2) induced an increase in pituitary 5-HT levels as well as a decrease in the 5-HIAA/5-HT ratio. In a second experiment, 20 mg MT per kilogram body weight was implanted for 10, 20 or 40 days into sexually immature male rainbow trout. Implanted rainbow trout showed increased testosterone and decreased E(2) levels. In the pituitary, MT induced long-term decreases in NE, DA, DOPAC and 5-HT levels, as well as in the DOPAC/DA ratio. Hypothalamic and telencephalic DA, NE and 5-HT levels were not affected by MT implantation. However, 5-HIAA levels and the 5-HIAA/5-HT ratio were reduced by MT implantation in both brain regions. These results show that chronic treatment with MT exerts both long-term and region-specific effects on NE, DA, and 5-HT contents and metabolism, and thus that this androgen could inhibit pituitary catecholamine and 5-HT synthesis. A possible role for testosterone in the control of pituitary dopaminergic activity and gonadotropin II release is also discussed.     

Aquaporin 4 regulates the effects of ovarian hormones on monoamine neurotransmission

Aquaporin 4 (AQP4) is the predominant water channels in the brain of mammals. Our previous study has reported that AQP4 knockout induced sex-specific alterations in neurotransmission, indicating that AQP4 might regulate the interaction between sex hormones and neurotransmission. In the present study, we found that AQP4 knockout decreased the concentrations of estrogen and progestogen. Further study showed that exogenous estrogen decreased DA and 5-HT in cortex, reduced DA and 5-HT in striatum, but increased 5-HT in hippocampus in AQP4+/+ male mice. However, in AQP4-/- male mice, exogenous estrogen almost did not alter the levels of neurotransmitters except for decreasing DA in cortex. In female mice, ovariectomy decreased DA in the striatum of AQP4+/+ mice, but did not alter the levels of DA in AQP4-/- mice. These findings reveal for the first time that AQP4 regulates not only water and ion homeostasis but also the functions of ovarian hormone and neurotransmitter.     

Ovarian maturation and oogenesis in the blue swimmer crab,Portunus pelagicus (Decapoda: Portunidae)

The study was aimed at understanding the process of reproduction and the changes happening in the ovary of Portunus pelagicus during maturation, which would be useful for its broodstock development for hatchery purposes. For that, tissue samples from different regions of the ovary at various stages of maturation were subjected to light and electron microscopy, and based on the changes revealed and the differences in ovarian morphology, the ovary was divided into five stages such as immature (previtellogenic oocytes), early maturing (early vitellogenic oocytes), late maturing (late vitellogenic oocytes), mature (vitellogenic oocytes), and spent (resorbing oocytes). The ovarian wall comprised of an outermost thin pavement epithelium, a middle layer of connective tissue, and an innermost layer of germinal epithelium. The oocytes matured as they moved from the centrally placed germinal zone toward the ovarian wall. The peripheral arrangement of nucleolar materials and the high incidence of cell organelles during the initial stages indicated vitellogenesis I. Movement of follicle cells toward oocytes in the early maturing stage and low incidence of mitochondria and endoplasmic reticulum in the ooplasm during late vitellogenic stage marked the commencement and end of vitellogenesis II, respectively. Yolk granules at various stages of development were seen in the ooplasm from late vitellogenic stage onwards. The spent ovary had an area with resorbing oocytes and empty follicle cells denoting the end of one reproductive cycle and another area with oogonial cells and previtellogenic oocytes indicating the beginning of the next.     

Cathepsin D Activity in the Vitellogenesis of Xenopus laevis

An ovarian extract of Xenopus laevis exhibited in SDS-PAGE analyses an activity cleaving vitellogenin to lipovitellins under mildly acidic conditions. This activity was pepstatin-sensitive and inhibited by monospecific anti-rat liver cathepsin D antibody and thus identified as cathepsin D. Immunoblot analysis showed that two proteins of 43 kDa and 36 kDa immunoreacted with the antibody.
Immunocytochemical staining revealed that the enzyme was located in the cortical cytoplasm of stage I and II oocytes and in small yolk platelets and nascent forms of large yolk platelets in the cortical cytoplasm of stage III oocytes. In stage IV and V oocytes, small yolk platelets retained the immuno-staining but large yolk platelets decreased it. No immuno-positive signals were observed in oocytes at stage VI. When examined by immunoelectron microscopy, gold particles indicated that cathepsin D was located on dense lamellar bodies in the cortical cytoplasm of stage I and II oocytes. The particles were located on primordial yolk platelets and on the superficial layer of small yolk platelets in stage III oocytes, while they were sparse or not present at all on large yolk platelets in stage IV and V oocytes. These results indicate that cathepsin D plays a key role in vitellogenesis by cleaving endocytosed vitellogenin to yolk proteins in developing oocytes.     

Neurotransmitter, opiodergic system, steroid-hormone interaction and involvement in the replacement therapy of sexual disorders

Dopamine (DA) and serotonin (5-HT) are the neurotransmitters most directly involved in sexual activity. DA plays a stimulatory role while 5-HT has an inhibitory effect. The two monoaminergic systems modulate the secretion of many hormones (GnRH, LH, testosterone, prolactin and endorphins) involved in sexual functional capacity. Furthermore, hormones influence synthesis and storage of brain neurotransmitters. Impotence can often be associated to clinical depression and altered neurotransmitter function. Moreover, stress represents an unbalance between various neurotransmitter systems and can induce impotence especially when disorders of the endorphinic system are present. Replacement therapy is based upon the understanding of these basic concepts. Impotence due to an underlying depressive illness must be treated with dopaminergic antidepressant drugs; while in stressful conditions a good response to the naloxone test is the preliminary criterion to subsequent naltrexone treatment. When a hormonal deficiency has been proved, the hormone replacement therapy is of course highly effective (gonadotropins in hypogonadotropic syndromes, testosterone in aging, etc.). Finally, idiopathic impotence could be treated by DA agonist and/or 5-HT antagonist drugs either alone or better yet in association with psychotherapy.     

The stage of ovarian development affects organ expression of vitellogenin as well as the morphometry and ultrastructure of germ cells in the freshwater prawn Macrobrachium amazonicum (Heller, 1862)

The objective was to characterize vitellogenin expression in the ovary and hepatopancreas, and to describe the morphometry and ultrastructure of oocytes, in the freshwater prawn Macrobrachium amazonicum at various stages of ovarian development. Five ovarian stages were defined: (I) immature, (II) maturing, (III) mature, (IV) spawned, and (V) reorganized. Ovaries and hepatopancreas were analyzed by immunohistochemistry for vitellogenin expression. Vitellogenin expression in both ovary and hepatopancreas was predominantly widespread, beginning at Stage I, peaking at Stage III, and decreasing in Stages IV and V. Characterization of the ovary included measurement of the following germ cell types: oogonia (OG), and previtellogenic (PV), early vitellogenesis (EV), advanced vitellogenesis (AV), and mature (M) oocytes. Mean ± SD diameter of OG and EV oocytes in Stages I (14.2 ± 5.5 and 119.8 ± 15.7 μm) and II (17.9 ± 4.8 and 114.3 ± 34.6 μm), respectively, were significantly different from that in Stages IV (16.6 ± 4.7 and 107.0 ± 24.6 μm) and V (14.4 ± 4.1 and 101.0 ± 25.2 μm). Both scanning and transmission electron microscopy enabled identification of EV, AV and M oocytes based on the presence of a nucleus, and the organization and distribution of yolk in the cytoplasm. In summary, vitellogenesis occurred both in the hepatopancreas and ovary, with the ovary expressing vitellogenin starting as early as Stage I. This process promoted accumulation of yolk and growth of oocytes, thus favoring sexual maturation of females. This knowledge may be applied to improve production of farmed M. amazonicum.