Long term estradiol-17β administration changes population of the dorsal root ganglia neurons innervating the ovary in the sexually mature gilts

Intrinsic innervation of the ovary and its variations in the rat senescence process

Ovarian functions decrease with perimenopause. The ovary has extrinsic innervation, but the neural influence on ovarian functions and dysfunction is not well-studied. The present study aimed to biochemically and morphometrically characterize the intrinsic neurons in ovaries from young adult, middle-aged, and senescent Long Evans CII-ZV rats (3, 12, and 15 months old, respectively). Ovaries were extracted from four rats of each age group (n = 12 total), cryopreserved, and processed for immunofluorescence studies with the primary NeuN/β-tubulin and NeuN/tyrosine hydroxylase (TH) antibodies. The soma area and number of intrinsic neurons in the ovarian stroma, surrounding follicles, corpus luteum, or cyst were evaluated. The intrinsic neurons were grouped in cluster-like shapes in ovarian structures. In senescent rats, the intrinsic neurons were mainly localized in the ovarian stroma and around the cysts. The number of neurons was lower in senescent rats than in young adult rats (p < 0.05), but the soma size was larger than in young adult rats. Immunoreactivity to TH indicated the presence of noradrenergic neurons in the ovary with the same characteristics as NeuN/β-tubulin, which indicates that they are part of the same neuronal group. Taken together, the findings indicate that the intrinsic neurons may be related to the loss of ovarian functions associated with aging.

Endometritis decreases the population of uterine neurons in the paracervical ganglion and changes the expression of sympathetic neurotransmitters in sexually mature gilts

BACKGROUND

The focus of the study was to examine the impact of the inflamed uterus on the population of the paracervical ganglion (PCG) uterus-innervating perikarya and their chemical coding. Fast Blue retrograde tracer was injected into the wall of uterine horns on the 17th day of the first studied estrous cycle. After 28 days, either Escherichia coli suspension or saline was applied to the horns of the uterus, whereas the control group received laparotomy only. Eight days after the above-mentioned procedures, uterine cervices with PCG were collected. Both macroscopic and histopathologic examinations confirmed severe acute endometritis in the Escherichia coli-injected uteri. The double immunofluorescence method was used to analyze changes in the PCG populations coded with dopamine-β-hydroxylase (DβH) and/or neuropeptide Y (NPY), somatostatin (SOM), vasoactive intestinal polypeptide (VIP) and neuronal isoform of nitric oxide synthase (nNOS).

RESULTS

The use of Escherichia coli lowered the total number of Fast Blue-positive neurons. Moreover, an increase in DβH+/VIP+, DβH+/NPY+, DβH+/SOM + and DβH+/nNOS + expressing perikarya was noted. A rise in non-noradrenergic VIP-, SOM- and nNOS-immunopositive populations was also recorded, as well as a drop in DβH-positive neurotransmitter-negative neurons.

CONCLUSIONS

To sum up, inflammation of the uterus has an impact on the neurochemical properties of the uterine perikarya in PCG, possibly affecting the functions of the organ.

Endometritis affects chemical coding of the dorsal root ganglia neurons supplying uterus in the sexually mature gilts

This study reports on the influence of experimentally-induced uterine inflammation on chemical phenotypes, number and distribution of neurons in the dorsal root ganglia (DRGs) innervating the uterus in sexually mature gilts. On day 17 of the first studied estrous cycle, the uterine horns were injected with retrograde tracer Fast Blue (FB). After 28 days (on an expected day 3 of third studied estrous cycle), 50 ml of either saline (group SAL) or Escherichia coli (E. coli) suspension (10⁹ colony-forming units/ml, group E. coli) were injected into each uterine horn. In the control pigs (group CON), only laparotomy was performed. Eight days later DRGs and uteri were collected. All infected gilts developed severe form of acute endometritis. By use of double immunofluorescence labelling the numbers of uterine perikarya expressing substance P (SP), calcitonin gene-related peptide (CGRP), neurokinin A (NKA), galanin (GAL) and pituitary adenylate cyclase-activating polypeptide (PACAP) were analyzed. Injection of E. coli decreased the total number of the FB positive perykaria in the Th10-S4 DRGs. We revealed an increase in the populations of uterine perikarya coded SP⁺/CGRP^-, SP⁺/NKA^-, SP^-/NKA⁺, SP⁺/GAL⁺, SP⁺/GAL^-, SP^-/GAL⁺, SP⁺/PACAP⁺ and SP^-/PACAP⁺. Our results suggest that uterine inflammation affects both the spatial and neurochemical organization pattern of uterine sensory innervation. Additionally, the inflammation may affect the transmission of sensory information from uterus to spinal cord.

Genomics and metabolomics of post-weaning return to estrus

The weaning-to-estrus interval is a multifaceted trait that has the potential to substantially improve production efficiency in today's global swine industry, if variation in this measure can be reduced. Systems-biology approaches should help close the knowledge gap and increase selection tools and management strategies-such as gilt development programs, farrowing, and lactation feeding programs-to decrease the weaning-to-estrus interval. Metabolomics, the study of small compounds within biofluids and tissues, provides links between genotype and phenotype. Given the complexity and influence of the environment on the weaning-to-estrus interval, incorporating metabolomics data will provide valuable insight and guidance for future physiological as well as genetic and genomic strategies to reduce this interval, thereby improving sow productivity.

Porcine dorsal root ganglia ovarian neurons are affected by long lasting testosterone treatment

We studied the effect of testosterone overdose on the number, distribution and chemical coding of ovarian neurons in the dorsal root ganglia (DRGs) in pigs. On day 3 of the estrous cycle, the ovaries of both the control and experimental gilts were injected with retrograde tracer Fast Blue. From day 4 of the estrous cycle to the expected day 20 of the second studied cycle, the experimental gilts were injected with testosterone, while the control gilts received oil. After the completion of the protocol the Th16-L5 DRGs were collected. Injections of testosterone increased the testosterone (~3.5 fold) and estradiol-17beta (~1.6 fold) levels in the peripheral blood, and reduced the following in the DRGs: the total number of the Fast Blue-positive perikarya, the population of perikarya in the L2-L4 ganglia, and the numbers of SP(+)/CGRP(+), SP(+)/PACAP(+), SP(+)/nNOS(+) and SP(-)/nNOS(+) perikarya. In the testosterone-injected gilts, the populations of SP(+)CGRP(-), small and large androgen receptors-expressing perikarya were increased. These results suggest that elevated androgen levels during pathological states may regulate the transmission of sensory modalities from the ovary to the spinal cord, and antidromic regulation of the ovarian functions.

Non-targeted Plasma Metabolome of Early and Late Lactation Gilts

Female pigs nursing their first litter (first-parity gilts) have increased energy requirements not only to support their piglets, but they themselves are still maturing. Non-targeted plasma metabolomics were used to investigate the differences between (1) post-farrowing and weaning (early or late lactation), (2) degree of body condition loss after lactation (extreme or minimal), and (3) interactions; to potentially identify compounds or pathways that could aide in alleviating energetic demands of lactation in gilts. Twenty first-parity gilts were selected with similar (P ≥ 0.4475) number of piglets born and nursed, and similar (P ≥ 0.3141) body condition traits (e.g., body weight and backfat thickness) post-farrowing, yet exhibited minimal or extreme loss (P ≤ 0.0094) in body weight (8.6 ± 1.48 kg and 26.1 ± 1.90 kg, respectively) and backfat thickness (1.3 ± 0.67 mm and 4.7 ± 0.86 mm, respectively) following lactation (weaning). Plasma samples from first-parity gilts at post-farrowing and weaning were investigated using UPLC-MS and GC-MS to generate a comprehensive metabolic profile. Each approach yielded approximately 700 detected features. An ANOVA was performed on each detected compound in R for time of collection, body condition change, and the interaction, followed by a false discovery correction. Two unknown features were different (P ≤ 0.05) for extreme vs. minimal body condition change. Several compound differences (P ≤ 0.05) were identified between post-farrowing and weaning. Thirty-two features detected by UPLC-MS had at least a log₂ fold-change of ±1.0 while only 18 features had a log₂ fold-change of ±0.6 or more for the significant GC-MS features. Annotation implicated various metabolic pathways. Creatinine was greater at weaning (P = 0.0224) and others have reported increased serum concentrations of creatinine in response to body weight loss. Hippurate and caprolactam, associated with protein catabolism, were also greater (P ≤ 0.0166) at weaning. Phospholipid features (P ≤ 0.0347) and inositol-related features (P ≤ 0.0236) were also greater at weaning. Inositol features may exert insulin-like effects. The energetic demands of lactation in gilts nursing their first litter indicated a greater difference exists between early and late lactation regardless of body condition loss.

Long-term treatment with testosterone alters ovary innervation in adult pigs

BACKGROUND

Intraovarian distribution and density of nerve fibres immunoreactive (IR) to protein gene product 9.5 (PGP 9.5) and containing dopamine-β-hydroxylase (DβH), neuropeptide Y (NPY), somatostatin (SOM), galanin (GAL) were determined.

METHODS

From day 4 of the first oestrous cycle to day 20 of the second studied cycle, experimental gilts (n = 3) were injected with testosterone (T), while control gilts (n = 3) received corn oil.

RESULTS

After T administration the numbers of fibres IR to PGP 9.5 and fibres IR to DβH, NPY and SOM were decreased. Fewer PGP 9.5- and DβH-IR terminals were observed within the ground plexus and around arteries and medullar veins, and medium tertiary follicles, and DβH-IR terminals in the vicinity of small tertiary follicles. T decreased the density of NPY-IR fibres in the medullar part of the ground plexus, and SOM-IR in the cortical part of the ground plexus.

CONCLUSIONS

The obtained data show that long-term T treatment of gilts decreases the total number of intraovarian fibres, including sympathetic ones. These results suggest that elevated T levels that occur during pathological states may affect the innervation pattern of ovaries, and their function(s).

Estrogen and female reproductive tract innervation: cellular and molecular mechanisms of autonomic neuroplasticity

The female reproductive tract undergoes remarkable functional and structural changes associated with cycling, conception and pregnancy, and it is likely advantageous to both individual and species to alter relationships between reproductive tissues and innervation. For several decades, it has been appreciated that the mammalian uterus undergoes massive sympathetic axon depletion in late pregnancy, possibly representing an adaptation to promote smooth muscle quiescence and sustained blood flow. Innervation to other structures such as cervix and vagina also undergo pregnancy-related changes in innervation that may facilitate parturition. These tissues provide highly tractable models for examining cellular and molecular mechanisms underlying peripheral nervous system plasticity. Studies show that estrogen elicits rapid degeneration of sympathetic terminal axons in myometrium, which regenerate under low-estrogen conditions. Degeneration is mediated by the target tissue: under estrogen's influence, the myometrium produces proteins repulsive to sympathetic axons including BDNF, neurotrimin, semaphorins, and pro-NGF, and extracellular matrix components are remodeled. Interestingly, nerve depletion does not involve diminished levels of classical sympathetic neurotrophins that promote axon growth. Estrogen also affects sympathetic neuron neurotrophin receptor expression in ways that appear to favor pro-degenerative effects of the target tissue. In contrast to the uterus, estrogen depletes vaginal autonomic and nociceptive axons, with the latter driven in part by estrogen-induced suppression of BMP4 synthesis. These findings illustrate that hormonally mediated physiological plasticity is a highly complex phenomenon involving multiple, predominantly repulsive target-derived factors acting in concert to achieve rapid and selective reductions in innervation.

Co-expression patterns of cocaine- and amphetamine-regulated transcript (CART) with neuropeptides in dorsal root ganglia of the pig

In the present study the neuronal distribution of CART was evaluated immunohistochemically in porcine dorsal root ganglia (DRGs). In co-localization studies the co-expression patterns of CART with SP, CGRP, galanin, CALB and LENK were investigated by means of triple immunohistochemical stainings. In porcine DRGs, the expression of CART was found in approximately 5% of primary sensory neurons. The vast majority (ca. 95%) of CART-immunoreactive (IR) neurons were small and middle sized, and only 5% were categorized as large. CART-IR neurons additionally exhibiting the presence of SP/CGRP (ca. 12%), SP/CALB (ca. 12%), SP/LENK (ca. 5%) were found. The vast majority of CART-IR/CGRP-IR neurons did not display immunoreaction to SP (ca. 60%). Subclasses of CART-IR/LENK-IR/SP-negative (ca. 5%), as well as CART-IR/CALB-IR/SP-negative neurons (ca. 10%), were also visualized. In addition, CART-IR neurons with no immunoreactivities to any of the neuropeptides studied were also shown. In porcine DRGs none of the CART-IR neurons exhibited the presence of galanin. The results obtained in the study suggest that CART may functionally modulate the activity of the porcine primary sensory neurons. It is concluded that co-expression of CART with CGRP, SP, LENK and CALB in subsets of the pig L1-L6 DRGs neurons provide anatomical evidence for a CART role in pain processing.

Long-term testosterone administration affects the number of paracervical ganglion ovary-projecting neurons in sexually mature gilts

The influence of testosterone (T) overdose on the number and distribution of ovarian neurons in the paracervical ganglion (PCG) in pigs was examined. To identify the ovarian neurons, on day 3 of the estrous cycle, the ovaries of both the control and experimental gilts were injected with retrograde neuronal tracer Fast Blue. From next day to the expected day 20 of the second studied cycle, experimental gilts were injected with T, while control gilts received oil. The PCG was then collected and processed for double-labeling immunofluorescence. T injections increased the T (∼3.5-fold) and estradiol-17β (∼1.6-fold) levels in the peripheral blood, and reduced the following in the PCG: the total number of Fast Blue-positive neurons, the number of perikarya in the lateral part of the PCG, the numbers of VAChT(+)/SOM(+), VAChT(+)/VIP(+), VAChT(+)/nNOS(+), VAChT(+)/VIP(-), VAChT(+)/DβH(-), VAChT(-)/SOM(-), VAChT(-)/VIP(-), VAChT(-)/nNOS(-) and VAChT(-)/DβH(-) perikarya, In the T-affected PCG, the populations of ovarian perikarya coded VAChT(-)/SOM(+), VAChT(-)/VIP(+) and VAChT(-)/DβH(+), and expressing androgen receptor were increased. After T treatment within the PCG dropped the density of nerve fibers expressing VAChT and/or SOM, VIP, DβH. Obtained data suggest that elevated androgen levels occurring during pathological processes may regulate ovary function(s) by affecting the PCG gonad-supplying neurons.

Changes in the cholinergic innervation pattern of porcine ovaries with cysts induced by dexamethasone administration

We revealed earlier that induction of ovarian cysts in gilts by dexamethasone phosphate disodium salt (DXM) administration from the follicular phase of the estrous cycle (EC) changed the cholinergic innervation of the gonad. In the present study, the innervation of porcine ovaries by vesicular acetylcholine transporter (VAChT)-, neuronal nitric oxide synthase (nNOS)-, vasoactive intestinal peptide (VIP)- and somatostatin (SOM)-immunoreactive (IR) fibres, after induction of cystic changes from the middle luteal phase of the EC, was determined. The cystic changes were induced by DXM injections from days 7 to 21 of the EC, and 11 days later, the ovaries were collected. In the cystic ovaries, VAChT-, nNOS- and SOM-IR fibres were found around cysts and small tertiary follicles; nNOS-IR and also VAChT-IR fibres were observed near secondary follicles and veins; and VAChT- and nNOS-IR fibres were not found around cortical arteries. The number of VIP-IR fibres increased near the cysts and within the ground plexus, while the number of VAChT-IR fibres decreased within the medullar part of this structure. Thus, our study showed changes in the cholinergic innervation pattern of the porcine cystic ovaries induced from the middle phase of the cycle and confirmed that cystic ovary innervation depends partly on the phase of the EC in which the induction of cysts was started.

Reduction of the number of neurones in the caudal mesenteric ganglion innervating the ovary in sexually mature gilts following testosterone administration

The effect of testosterone on the morphological and chemical plasticity of the porcine caudal mesenteric ganglion (CaMG) ovary-projecting neurones was investigated. To identify the neurones on day 3 of the oestrous cycle, the ovaries of both the control and experimental gilts were injected with Fast Blue retrograde neuronal tracer. From next day until day 20 of the anticipated second studied cycle, experimental gilts were injected with testosterone, whereas control gilts received oil. Testosterone injections increased testosterone (by approximately 3.5-fold) and 17β-oestradiol (by approximately 1.6-fold) levels in the peripheral blood and decreased the following in the CaMG: the total number of Fast Blue-positive perikarya (including small ones); the population of small perikarya in the caudal, ventral and dorsal ganglional regions; the numbers of dopamine-β-hydroxylase (DβH) and/or neuropeptide Y (NPY), somatostatin (SOM), galanin (GAL) small and large perikarya; the numbers of small perikarya containing DβH (but not NPY, SOM, GAL); and the density of DβH and/or NPY, SOM nerve fibres. A disappearance of small and large non-noradrenergic perikarya and an increase in the total number of androgen receptor-immunoreactive perikarya was noted. Our results suggest that elevated androgen levels occurring during pathological states may regulate ovary function(s) by affecting the CaMG gonad-supplying neurones.

Long-term estradiol-17β administration changes the population of paracervical ganglion neurons supplying the ovary in adult gilts

The aim of this study was to determine the influence of estradiol-17β (E(2)) overdose on the number and distribution of ovarian parasympathetic neurons in the paracervical ganglion (PCG) in adult pigs. To identify the neurons innervating gonads on day 3 of the estrous cycle, the ovaries of both the control and experimental gilts were injected with retrograde neuronal tracer Fast Blue. From next day to the expected day 20 of the second studied cycle, experimental gilts were injected with E(2), while control gilts received oil. The PCG were then collected and processed for double-labeling immunofluorescence. Injections of E(2) increased the E(2) level in the peripheral blood approximately four- to fivefold and reduced the following in the PCG: the total number of Fast Blue-positive neurons; the number of perikarya in the lateral part of the PCG; the numbers of vesicular acetylcholine transporter (VAChT)(+)/somatostatin(+), VAChT(+)/vasoactive intestinal polypeptide (VIP)(+), VAChT(+)/neuronal isoform of nitric oxide synthase(+), VAChT(+)/VIP(-), VAChT(+)/dopamine β-hydroxylase (DβH)(-), VAChT(-)/VIP(-), and VAChT(-)/DβH(-) perikarya; and the total number of perikarya expressing estrogen receptors (ERs) subtype α and/or β. In summary, long-term E(2) treatment of adult gilts downregulates the population of both cholinergic and ERs expressing the PCG ovary-projecting neurons. Our results suggest that elevated E(2) levels occurring during pathological states may regulate gonadal function(s) by affecting ovary-supplying neurons.