Interleukin-1 Beta (IL1B) and Nerve Growth Factor (NGF): Key Players in Rabbit Reproductive Regulation

Several seminal plasma components, besides NGF, are implicated as ovulation-inducing factors in mammals. This study investigated the IL1B and its receptor IL1R1 in the testis (T), male accessory glands, prostate (P) and seminal vesicles (SV), and uterus (U) of adult rabbits using immunohistochemistry (IHC) and quantitative reverse transcription PCR (RT-qPCR). We also assessed the presence of IL1B in seminal plasma through Western blotting (WB) and examined the interaction between IL1B and NGF in vitro by measuring their production with enzyme-linked immunosorbent assay (ELISA) in the presence of NGF and IL1B alone or with their respective receptor antagonists. IHC revealed IL1B system expression in all reproductive organs studied, with IL1B and IL1R1 localized to the germinative epithelium of the T and the epithelial cells of the accessory glands and U. IL1B gene transcript levels were significantly higher (p < 0.01) in the P and SV compared to the T, while IL1R1 levels were significantly higher (p < 0.001) in the P compared to the other tissues, while IL1R1 levels were three times higher (p < 0.001) in the P. WB confirmed the presence of IL1B in seminal plasma with a 30-35 kDa band. The in vitro study demonstrated that IL1B increased (p < 0.05) basal NGF production in the U, whereas NGF had no effect on IL1B production. These findings provide evidence of the expression of the IL1B/IL1R1 system in both male and female rabbit reproductive tracts and suggest that IL1B in seminal plasma may influence uterine endocrine activity. The results propose a potential role for IL1B in ovulation, in conjunction with NGF, supporting that ovulation may involve inflammatory-like processes.

Neuronal segmentation in cephalopod arms

The prehensile arms of the cephalopod are among these animals most remarkable features, but the neural circuitry governing arm and sucker movements remains largely unknown. We studied the neuronal organization of the adult axial nerve cord (ANC) of Octopus bimaculoides with molecular and cellular methods. The ANCs, which lie in the center of every arm, are the largest neuronal structures in the octopus, containing four times as many neurons as found in the central brain. In transverse cross section, the cell body layer (CBL) of the ANC wraps around its neuropil (NP) with little apparent segregation of sensory and motor neurons or nerve exits. Strikingly, when studied in longitudinal sections, the ANC is segmented. ANC neuronal cell bodies form columns separated by septa, with 15 segments overlying each pair of suckers. The segments underlie a modular organization to the ANC neuropil: neuronal cell bodies within each segment send the bulk of their processes directly into the adjoining neuropil, with some reaching the contralateral side. In addition, some nerve processes branch upon entering the NP, forming short-range projections to neighboring segments and mid-range projections to the ANC segments of adjoining suckers. The septa between the segments are employed as ANC nerve exits and as channels for ANC vasculature. Cellular analysis establishes that adjoining septa issue nerves with distinct fiber trajectories, which across two segments (or three septa) fully innervate the arm musculature. Sucker nerves also use the septa, setting up a nerve fiber "suckerotopy" in the sucker-side of the ANC. Comparative anatomy suggests a strong link between segmentation and flexible sucker-laden arms. In the squid Doryteuthis pealeii, the arms and the sucker-rich club of the tentacles have segments, but the sucker-poor stalk of the tentacles does not. The neural modules described here provide a new template for understanding the motor control of octopus soft tissues. In addition, this finding represents the first demonstration of nervous system segmentation in a mollusc.

Functional organization of visual responses in the octopus optic lobe

Cephalopods are highly visual animals with camera-type eyes, large brains, and a rich repertoire of visually guided behaviors. However, the cephalopod brain evolved independently from that of other highly visual species, such as vertebrates, and therefore the neural circuits that process sensory information are profoundly different. It is largely unknown how their powerful but unique visual system functions, since there have been no direct neural measurements of visual responses in the cephalopod brain. In this study, we used two-photon calcium imaging to record visually evoked responses in the primary visual processing center of the octopus central brain, the optic lobe, to determine how basic features of the visual scene are represented and organized. We found spatially localized receptive fields for light (ON) and dark (OFF) stimuli, which were retinotopically organized across the optic lobe, demonstrating a hallmark of visual system organization shared across many species. Examination of these responses revealed transformations of the visual representation across the layers of the optic lobe, including the emergence of the OFF pathway and increased size selectivity. We also identified asymmetries in the spatial processing of ON and OFF stimuli, which suggest unique circuit mechanisms for form processing that may have evolved to suit the specific demands of processing an underwater visual scene. This study provides insight into the neural processing and functional organization of the octopus visual system, highlighting both shared and unique aspects, and lays a foundation for future studies of the neural circuits that mediate visual processing and behavior in cephalopods.

Highlights

The functional organization and visual response properties of the cephalopod visual system are largely unknownUsing calcium imaging, we performed mapping of visual responses in the octopus optic lobeVisual responses demonstrate localized ON and OFF receptive fields with retinotopic organizationON/OFF pathways and size selectivity emerge across layers of the optic lobe and have distinct properties relative to other species.

Plumeria acuminata: A Systematic in vivo Evaluation for Its Anti-ovulatory and Anti-Implantation Features

Background:

Fertility control becomes necessary for under-developed and developing nations for the betterment of the economy, environment, and society. Plant Plumeria acuminata, “Temple tree or Frangipani”, of the Apocynaceae family has exhibited several activities similar to contraceptive medicine and is widely distributed in India.

Objective:

Present investigation aimed to study the anti-ovulatory and anti-implantation activities of ethanolic extract from P. acuminata leaves and roots in Wistar rats.

Methods:

Ethanolic extracts of P. acuminata leaves and roots were subjected to qualitative phytochemical analysis and acute toxicity test. Immature female rats were used to explore anti-ovulatory characteristics administering HCG as a standard ovulation-inducing drug. Mated females were used for exploring anti-implantation characteristics. Levonorgestrel and Ethinylestradiol were administered as standard anti-implantation drugs. Morphological, hematological, hormonal, and histological examinations were performed.

Results:

LD50 value i.e., 2000 mg/kg from acute toxicity test resulted in the selection of 100, 200, and 400 mg/kg dose values for both leaf and root extracts. Treatment with these brought ~2-54%, ~5-48%, and ~1-68% changes respectively in the hormonal, growth factors’ and cytokines’ profile. Ovarian histology revealed restricted follicle maturation and ovulation whereas uterine histology unveiled a ~5-28% decrease in the endometrium thickness making it unreceptive for implantation after treatment with PAL and PAR extracts.

Conclusion:

Anti-ovulatory and anti-implantation results obtained here can be attributed to the presence of plumericin, sterol as well as triterpene groups of phytochemicals from ethanolic extracts of leaves and roots, making them potent contestants for studies on future contraceptive medicines.

Assessment of Biostimulation Methods Based on Chemical Communication in Female Doe Reproduction

Biostimulation is an animal management practice that helps improve reproductive parameters by modulating animal sensory systems. Chemical signals, mostly known as pheromones, have a great potential in this regard. This study was conducted to determine the influence of short-term female rabbit exposure to different conditions, mainly pheromone-mediated, on reproductive parameters of inseminated does. Groups of 60 females/each were exposed to (1) female urine, (2) male urine, (3) seminal plasma and (4) female-female (F-F) separated, just before artificial insemination, and compared to a 'golden method' female-female interaction. The following reproductive parameters were analyzed for each group: receptivity (vulvar color), fertility (kindling rate), prolificacy and number of born alive and dead kits/litter. Our results showed that the biostimulation methods employed in this experiment did not significantly improve any of the analyzed parameters. However, female doe exposure to urine, especially to male urine, showed no significant higher fertility values (95.4%) when compared to the rest of the experimental conditions (on average 92.4%). Female-female interaction before artificial insemination, which is a common practice in rabbit farms, showed similar results as not establishing social interaction (F-F separated), which suggests that F-F interaction could be replaced by F-F separated, therefore avoiding unnecessary animal management and time cost. On the other hand, fertility ranges were lower for animals with a pale vulvar color whereas no differences were noticed among the other three colors which measure receptivity (pink, red, purple), thus suggesting that these three colors could be grouped together. Future studies should aim at determining potential chemical cues/pheromones released through bodily secretions that influence reproduction in rabbits, therefore contributing to animal welfare and to a natural image of animal production.

Physiology and modulation factors of ovulation in rabbit reproduction management

Rabbit is an induced ovulatory species, so ovulation takes place after mating. Traditionally, exogenous and synthetic hormonal factors (administered by intramuscular and intravaginal route) such as GnRH and analogues, or different physical procedures (i.e. stimulation by intravaginal cannula) have been used to induce ovulation in females when artificial insemination is applied in rabbit farms. Restriction and public rejection of the use of hormones is leading to the study of the seminal plasma components with potential action on ovulation induction. The aim of the present review is to collect and summarise the strategies used in recent years to trigger ovulation and improve rabbit fertility management with respect to more animal-friendly manipulation methods. Furthermore, special attention has been paid to the use of a semen component (as endogen molecule) such as beta nerve growth factor (β-NGF) in male and female rabbit reproductive physiology. This neurotrophin and its receptors (TrKA and p75NTR) are abundantly distributed in both male and female rabbit reproductive tracts, and it seems to have an important physiological role in sperm maturation and behaviour (velocity, apoptosis and capacitation), as well as a modulatory factor of ovulation. Endogen β-NGF is diluted in the seminal doses with the extenders; hence it could be considered an innovative and alternative strategy to avoid the current exogenous (by intramuscular route) and stressful hormonal treatments used in ovulation induction. Their addition in seminal dose could be more physiological and improve animal welfare in rabbit farms.

Effect of cat seminal plasma and purified llama ovulation-inducing factor (β-NGF) on ovarian function in queens

The present study aimed to determine the effect of cat seminal plasma and purified llama ovulation-inducing factor (β-NGF) on ovarian activity in queens. Queens (n = 6) were used for all the treatments in a crossover design with an interval time between treatments of three interestrus intervals. Forty-eight hours after the detection of an estrus vaginal cytology, queens were given cat seminal plasma (subcutaneous or intramuscular), purified llama ovulation-inducing factor (15 or 35 μg), hCG (75 UI), saline, or were mated with a male. A total of 192 estrous cycles were observed. Estrus length and serum estradiol concentration were 6 ± 1 days (range 2-10 d) and 38 pg/mL (range 10-75 pg/mL), respectively. Queens mated and given hCG showed higher serum progesterone concentration and longer interestrus interval (47 ± 5 d) than that of controls (10 ± 3 d). Sixty-seven percent of queens (4/6) treated with subcutaneous cat seminal plasma, and 17% of those treated with purified llama β-NGF showed high serum progesterone concentrations along with prolonged interestrus. However, intramuscular administration of cat seminal plasma produced interestrus intervals similar to controls (15 ± 5 d) and basal serum progesterone concentration (<0.50 ng/mL). This study demonstrates that the subcutaneous administration of cat seminal plasma induced ovulation in queens. Therefore, molecules present in cat seminal plasma, contribute to the induction of ovulation in queens. Identifying those molecules will improve the knowledge of queen's reproductive physiology. Also, it could offer a physiologic alternative to induce ovulation in queens when reproductive biotechnologies are used.

Nerve Growth Factor (NGF) and Animal Reproduction

Stimuli that lead to the release of gonadotropin-releasing hormone (GnRH) and pituitary gonadotropins and, consequently, ovulation in mammals fall into two broad categories. In the first, high plasma oestrogen concentrations induce the events that trigger ovulation, a characteristic of spontaneous ovulators. In the second, nerve stimuli occurring during mating reach the hypothalamus and trigger the release of GnRH and ovulation with a neuroendocrine reflex that characterizes induced ovulators.In this review, we will give an overview of the distribution of NGF and its expression in the different tissues of the male accessory sex glands, the main sites of NGF production. Next, we will highlight the role of NGF in sperm function and its potential cryopreserving role in artificial insemination techniques. Finally, we will evaluate the functions of NGF in ovulation, particularly in induced ovulators. Overall, the information obtained so far indicates that NGF is widely distributed in organs that regulate the reproductive activity, in both males and females. In spontaneous ovulators, NGF exerts mainly a luteotrophic action, while, in induced ovulators it is the main ovulation-inducing factor. A better understanding of the role of NGF in reproduction would be of great interest, since it could help finding innovative therapeutic aids to improve mammalian fertility.

New insights of the role of β-NGF in the ovulation mechanism of induced ovulating species

The type of stimuli triggering GnRH secretion has been used to classify mammalian species into two categories: spontaneous or induced ovulators. In the former, ovarian steroids produced by a mature follicle elicit the release of GnRH from the hypothalamus, but in the latter, GnRH secretion requires coital stimulation. However, the mechanism responsible for eliciting the preovulatory LH surge in induced ovulators is still not well understood and seems to vary among species. The main goal of this review is to offer new information regarding the mechanism that regulates coitus-induced ovulation. Analysis of several studies documenting the discovery of β-NGF in seminal plasma and its role in the control of ovulation in the llama and rabbit will be described. We also propose a working hypothesis regarding the sites of action of β-NGF in the llama hypothalamus. Finally, we described the presence of β-NGF in the semen of species categorized as spontaneous ovulators, mainly cattle, and its potential role in ovarian function. The discovery of this seminal molecule and its ovulatory effect in induced ovulators challenges previous concepts about the neuroendocrinology of reflex ovulation and has provided a new opportunity to examine the mechanism(s) involved in the cascade of events leading to ovulation. The presence of the factor in the semen of induced as well as spontaneous ovulators highlights the importance of understanding its signaling pathways and mechanism of action and may have broad implications in mammalian fertility.

Role of nerve growth factor in the reproductive physiology of female rabbits: A review

Rabbit does are reflex ovulators such that coitus is needed to release GnRH and elicit the LH surge that triggers the ovulation of mature oocytes. However, the mechanisms eliciting ovulation in this species remain unclear. One of the most promising recently discovered candidates with a role in female reproductive physiology is nerve growth factor beta (β-NGF). This neurotrophin and its high-affinity receptor TrkA and low affinity receptor p75, is present in all compartments of the ovary, oviduct and uterus suggesting a physiologic role in ovarian folliculogenesis, steroidogenesis, ovulation, luteogenesis and embryo development. Besides, evidence exists that β-NGF found in seminal plasma could exert a modulatory role in the female hypothalamus-pituitary-ovarian axis contributing to the adrenergic and cholinergic neuronal stimulus of GnRH neurons in an endocrine manner during natural mating. Probably, the paracrine and local roles of the neurotrophin in steroidogenesis and ovulation reinforce the neuroendocrine pathway that leads to ovulation. This review updates knowledge of the role of β-NGF in rabbit reproduction, including its possible contribution to the mechanisms of action that induce ovulation, and discusses perspectives for the future applications of this neurotrophin on rabbit farms.

New insights on a NGF-mediated pathway to induce ovulation in rabbits (Oryctolagus cuniculus)

To investigate the ovulatory mechanisms triggered by raw semen (RS) in rabbits, we examined the expression of nerve growth factor (NGF)-a supposed ovulation-inducing factor (OIF)-and cognate receptors in anterior pituitary, ovary, and cervix as well as plasma NGF and luteinizing hormone (LH) concentrations. Six does/group were sham-inseminated with sterile saline (PBS), naturally mated (NM), inseminated with RS alone or after lumbar anesthesia (ARS), or treatment with COX inhibitors (CIRS). Immunohistochemistry revealed positive signals for NGF and receptors in all tissues. RT-PCR confirmed the presence of the target transcripts in the same tissues, except NTRK1 in the cervix. Circulating NGF concentrations rose 3- to 6-fold (P < 0.01) 15 min after semen deposition into the genital tract of NM, RS, and ARS rabbits and remained sustained thereafter. Circulating NGF was 4-fold lower (P < 0.01) in CIRS than in RS does indicating that NGF is mainly synthesized by the uterus. A concomitant rise of LH and NGF concentrations was found in 83.3%, 50.0%, and 16.7% of NM, RS, and CIRS does, respectively, but not in ARS (despite high NGF circulating levels). Seminal plasma NGF concentration was 151.9 ± 9.25 μg/mL. The ovulatory responses were 0%, 83.3%, 66.7%, 16.7%, and 0% in PBS, NM, RS, ARS, and CIRS groups, respectively. Present data confirm that, although RS may induce ovulation via endocrine mechanisms through binding to NGF receptors in the ovary, a novel OIF-mediated neural mechanism facilitates ovulation in rabbits.

Effect of the Camelid's Seminal Plasma Ovulation-Inducing Factor/β-NGF: A Kisspeptin Target Hypothesis

Female mammals are classified into spontaneous and induced ovulators based on the mechanism eliciting ovulation. Ovulation in spontaneous species (e.g., human, sheep, cattle, horse, pigs, and most rodents) occurs at regular intervals and depends upon the circulating estradiol. However, in induced ovulators (e.g., rabbits, ferrets, cats, and camelids), ovulation is associated with coitus. In the later, various factors have been proposed to trigger ovulation, including auditory, visual, olfactory, and mechanic stimuli. However, other studies have identified a biochemical component in the semen of induced ovulators responsible for the induction of ovulation and named accordingly ovulation-inducing factor (OIF). In camelids, intramuscular or intrauterine administration of seminal plasma (SP) was shown to induce the preovulatory luteinizing hormone (LH) surge followed by ovulation and subsequent formation of corpus luteum. Recently, this OIF has been identified from SP as a neurotrophin, the β subunit of nerve growth factor (β-NGF). β-NGF is well known as promoting neuron survival and growth, but in this case, it appears to induce ovulation through an endocrine mode of action. Indeed, β-NGF may be absorbed through the endometrium to be conveyed, via the blood stream, to the central structures regulating the LH preovulatory surge. In this review, we provide a summary of the most relevant results obtained in the field, and we propose a working hypothesis for the central action of β-NGF based on our recent demonstration of the presence of neurons expressing kisspeptin, a potent stimulator of GnRH/LH, in the camel hypothalamus.

The Drosophila Accessory Gland as a Model for Prostate Cancer and Other Pathologies

The human prostate is a gland of the male reproductive tract, which together with the seminal vesicles, is responsible for most seminal fluid production. It is a common site of cancer, and unlike other glands, it typically enlarges in aging men. In flies, the male accessory glands make many major seminal fluid components. Like their human equivalents, they secrete proteins from several conserved families, including proteases, lectins, and cysteine-rich secretory proteins, some of which interact with sperm and affect fertility. A key protein, sex peptide, is not conserved in vertebrates but plays a central role in mediating long-term effects on females after mating. Although postmitotic, one epithelial cell type in the accessory glands, the secondary cell, continues to grow in adults. It secretes microvesicles called exosomes from the endosomal multivesicular body, which, after mating, fuse with sperm. They also appear to affect female postmating behavior. Remarkably, the human prostate epithelium also secretes exosomes, which fuse to sperm in vitro to modulate their activity. Exosomes from prostate and other cancer cells are increasingly proposed to play fundamental roles in modulating the tumor microenvironment and in metastasis. Here we review a diverse accessory gland literature, which highlights functional analogies between the male reproductive glands of flies and humans, and a critical role for extracellular vesicles in allowing seminal fluid to promote male interests within the female. We postulate that secondary cells and prostate epithelial cells use common mechanisms to control growth, secretion, and signaling, which are relevant to prostate and other cancers, and can be genetically dissected in the uniquely tractable fly model.