Spinal neurons activated with the urethrogenital reflex in the male rat

Spinal Transection Switches the Effect of Metabotropic Glutamate Receptor Subtype 7 from the Facilitation to Inhibition of Ejaculation

Metabotropic glutamate receptor subtype 7 (mGluR7) is a member of the group III mGluRs, which localize to presynaptic active zones of the central nervous system. We previously reported that mGluR7 knockout (KO) mice exhibit ejaculatory disorders, although they have normal sexual motivation. We hypothesized that mGluR7 regulates ejaculation by potentiating the excitability of the neural circuit in the lumbosacral spinal cord, because administration of the mGluR7-selective antagonist into that region inhibits drug-induced ejaculation. In the present study, to elucidate the mechanism of impaired ejaculation in mGluR7 KO mice, we eliminated the influence of the brain by spinal transection (spinalization). Unexpectedly, sexual responses of male mGluR7 KO mice were stronger than those of wild-type mice after spinalization. Histological examination indicated that mGluR7 controls sympathetic neurons as well as parasympathetic neurons. In view of the complexity of its synaptic regulation, mGluR7 might control ejaculation by multi-level and multi-modal mechanisms. Our study provides insight into the mechanism of ejaculation as well as a strategy for future therapies to treat ejaculatory disorders in humans.

Targeting GATA1 and p2x7r Locus Binding in Spinal Astrocytes Suppresses Chronic Visceral Pain by Promoting DNA Demethylation

Irritable bowel syndrome is a gastrointestinal disorder of unknown etiology characterized by widespread, chronic abdominal pain associated with altered bowel movements. Increasing amounts of evidence indicate that injury and inflammation during the neonatal period have long-term effects on tissue structure and function in the adult that may predispose to gastrointestinal diseases. In this study we aimed to investigate how the epigenetic regulation of DNA demethylation of the p2x7r locus guided by the transcription factor GATA binding protein 1 (GATA1) in spinal astrocytes affects chronic visceral pain in adult rats with neonatal colonic inflammation (NCI). The spinal GATA1 targeting to DNA demethylation of p2x7r locus in these rats was assessed by assessing GATA1 function with luciferase assay, chromatin immunoprecipitation, patch clamp, and interference in vitro and in vivo. In addition, a decoy oligodeoxynucleotide was designed and applied to determine the influence of GATA1 on the DNA methylation of a p2x7r CpG island. We showed that NCI caused the induction of GATA1, Ten-eleven translocation 3 (TET3), and purinergic receptors (P2X7Rs) in astrocytes of the spinal dorsal horn, and demonstrated that inhibiting these molecules markedly increased the pain threshold, inhibited the activation of astrocytes, and decreased the spinal sEPSC frequency. NCI also markedly demethylated the p2x7r locus in a manner dependent on the enhancement of both a GATA1–TET3 physical interaction and GATA1 binding at the p2x7r promoter. Importantly, we showed that demethylation of the p2x7r locus (and the attendant increase in P2X7R expression) was reversed upon knockdown of GATA1 or TET3 expression, and demonstrated that a decoy oligodeoxynucleotide that selectively blocked the GATA1 binding site increased the methylation of a CpG island in the p2x7r promoter. These results demonstrate that chronic visceral pain is mediated synergistically by GATA1 and TET3 via a DNA-demethylation mechanism that controls p2x7r transcription in spinal dorsal horn astrocytes, and provide a potential therapeutic strategy by targeting GATA1 and p2x7r locus binding.

Spinal interneurons of the lower urinary tract circuits

The storage and elimination of urine requires coordinated activity between muscles of the bladder and the urethra. This coordination is orchestrated by a complex system containing spinal, midbrain and forebrain networks. Normally there is a reciprocity between patterns of activity in urinary bladder sacral parasympathetic efferents and somatic motoneurons innervating the striatal external urethral sphincter muscle. At the spinal level this reciprocity is mediated by ensembles of excitatory and inhibitory interneurons located in the lumbar-sacral segments. In this review I will present an overview of currently identified spinal interneurons and circuits relevant to the lower urinary tract and will discuss their established or hypothetical roles in the cycle of micturition. In addition, a recently discovered auxiliary spinal neuronal ensemble named lumbar spinal coordinating center will be described. Sexual dimorphism and developmental features of the lower urinary tract which may play a significant role in designing treatments for patients with urine storage and voiding dysfunctions are also considered. Spinal cord injuries seriously damage or even eliminate the ability to urinate. Treatment of this abnormality requires detailed knowledge of supporting neural mechanisms, therefore various experiments in normal and spinalized animals will be discussed. Finally, a possible intraspinal mechanism will be proposed for organization of external urethral sphincter (EUS) bursting which represents a form of intermittent EUS relaxation in rats and mice.

Identification of CNS neurons innervating the levator ani and ventral bulbospongiosus muscles in male rats

INTRODUCTION

The pelvic striated muscles play an important role in mediating erections and ejaculation, and together these muscles compose a tightly coordinated neuromuscular system that is androgen sensitive and sexually dimorphic.

AIM

To identify spinal and brains neurons involved in the control of the levator ani (LA) and bulbospongiosus (BS) in the male adult and preadolescent rat.

METHODS

Rats were anesthetized, and the transsynaptic retrograde tracer pseudorabies virus (PRV) was injected into the LA muscle of adults or the ventral BS muscle in 30-day-old rats. After 3-5 days rats were sacrificed, and PRV-labeled neurons in the spinal cords and brains were identified using immunohistochemistry. The presence of gastrin-releasing peptide (GRP) in the lumbar spinal neurons was examined.

MAIN OUTCOMES MEASURES

The location and number of PRV-labeled neurons in the spinal cord and brain and GRP colocalization in the lumbar spinal cord.

RESULTS

PRV-labeled spinal interneurons were found distributed throughout T11-S1 of the spinal cord, subsequent to dorsal medial motoneuron infection. The majority of spinal interneurons were found in the lumbosacral spinal cord in the region of the dorsal gray commissure and parasympathetic preganglionic neurons. Preadolescent rats had more PRV-labeled spinal interneurons at L5-S1 where the motoneurons were located but relatively less spread rostrally in the spinal cord compared with adults. Lumbar spinothalmic neurons in medial gray of L3-L4 co-localized PRV and GRP. In the brain consistent labeling was seen in areas known to be involved in male sexual behavior including the ventrolateral medulla, hypothalamic paraventricular nucleus, and medial preoptic area.

CONCLUSION

Common spinal and brain pathways project to the LA and BS muscles in the rat suggesting that these muscles act together to coordinate male sexual reflexes. Differences may exist in the amount of synaptic connections/neuronal pathways in adolescents compared with adults.

Nuclear expression of PG-21, SRC-1, and pCREB in regions of the lumbosacral spinal cord involved in pelvic innervation in young adult and aged rats

In rats, ageing results in dysfunctional patterns of micturition and diminished sexual reflexes that may reflect degenerative changes within spinal circuitry. In both sexes the dorsal lateral nucleus and the spinal nucleus of the bulbospongiosus, which lie in the L5-S1 spinal segments, contain motor neurons that innervate perineal muscles, and the external anal and urethral sphincters. Neurons in the sacral parasympathetic nucleus of these segments provide autonomic control of the bladder, cervix and penis and other lower urinary tract structures. Interneurons in the dorsal gray commissure and dorsal horn have also been implicated in lower urinary tract function. This study investigates the cellular localisation of PG-21 androgen receptors, steroid receptor co-activator one (SRC-1) and the phosphorylated form of c-AMP response element binding protein (pCREB) within these spinal nuclei. These are components of signalling pathways that mediate cellular responses to steroid hormones and neurotrophins. Nuclear expression of PG-21 androgen receptors, SRC-1 and pCREB in young and aged rats was quantified using immunohistochemistry. There was a reduction in the number of spinal neurons expressing these molecules in the aged males while in aged females, SRC-1 and pCREB expression was largely unchanged. This suggests that the observed age-related changes may be linked to declining testosterone levels. Acute testosterone therapy restored expression of PG-21 androgen receptor in aged and orchidectomised male rats, however levels of re-expression varied within different nuclei suggesting a more prolonged period of hormone replacement may be required for full restoration.

Synaptic activation of bulbospongiosus motoneurons via dorsal gray commissural inputs

Ejaculation is controlled by coordinated and rhythmic contractions of bulbospongiosus (BSM) and ischiocavernosus muscles. Motoneurons that innervate and control BSM contractions are located in the dorsomedial portion of the ventral horn in the L(5-6) spinal cord termed the dorsomedial (DM) nucleus. We characterized intrinsic properties of DM motoneurons as well as synaptic inputs from the dorsal gray commissure (DGC). Electrical stimulation of DGC fibers elicited fast inhibitory and excitatory responses. In the presence of glutamate receptor antagonists, both fast GABAergic as well as glycinergic inhibitory postsynaptic potentials (IPSPs) were recorded. No slow GABA(B)-mediated inhibition was evident. In the presence of GABA(A) and glycine receptor antagonists, DGC stimulation elicited fast glutamatergic excitatory responses that were blocked by application of CNQX. Importantly, a slow depolarization (timescale of seconds) was routinely observed that sufficiently depolarized the DM motoneurons to fire "bursts" of action potentials. This slow depolarization was elicited by a range of stimulus train frequencies and was insensitive to glutamate receptor antagonists (CNQX and d-APV). The slow depolarization was accompanied by an increase in membrane resistance with an extrapolated reversal potential near the K(+) Nernst potential. It was mediated by the combination of the block of a depolarization-activated K(+) current and the activation of a QX-314-sensitive cation current. These results demonstrate that fast synaptic responses in DM motoneurons are mediated primarily by glutamate, GABA, and glycine receptors. In addition, slow nonglutamatergic excitatory postsynaptic potentials (EPSPs), generated through DGC stimulation, can elicit burstlike responses in these neurons.

Characterization of bulbospongiosus muscle reflexes activated by urethral distension in male rats

The urethrogenital reflex (UGR) is used as a surrogate model of the autonomic and somatic nerve and muscle activity that accompanies ejaculation. The UGR is evoked by distension of the urethra and activation of penile afferents. The current study compares two methods of elevating urethral intraluminal pressure in spinalized, anesthetized male Sprague-Dawley rats ( n = 60). The first method, penile extension UGR, involves extracting the penis from the foreskin, so that urethral pressure rises due to a natural anatomical flexure in the penis. The second method, penile clamping UGR, involves penile extension UGR with the addition of clamping of the glans penis. Groups of animals were prepared that either received no additional treatment, surgical shams, or received bilateral nerve cuts (4 nerve cut groups): either the pudendal sensory nerve branch (SbPN), the pelvic nerves, the hypogastric nerves, or all three nerves. Penile clamping UGR was characterized by multiple bursts, monitored by electromyography (EMG) of the bulbospongiosus muscle (BSM) accompanied by elevations in urethral pressure. The penile clamping UGR activity declined across multiple trials and eventually resulted in only a single BSM burst, indicating desensitization. In contrast, the penile extension UGR, without penile clamping, evoked only a single BSM EMG burst that showed no desensitization. Thus, the UGR is composed of two BSM patterns: an initial single burst, termed urethrobulbospongiosus (UBS) reflex and a subsequent multiple bursting pattern (termed ejaculation-like response, ELR) that was only induced with penile clamping urethral occlusion. Transection of the SbPN eliminated the ELR in the penile clamping model, but the single UBS reflex remained in both the clamping and extension models. Pelvic nerve (PelN) transection increased the threshold for inducing BSM activation with both methods of occlusion but actually unmasked an ELR in the penile extension method. Hypogastric nerve (HgN) cuts did not significantly alter any parameter. Transection of all three nerves eliminated BSM activation completely. In conclusion, penile clamping occlusion recruits penile and urethral primary afferent fibers that are necessary for an ELR. Urethral distension without significant penile afferent activation recruits urethral primary afferent fibers carried in either the pelvic or pudendal nerve that are necessary for the single-burst UBS reflex.

Muscarinic receptor antagonism at the spinal cord level causes inhibitory effects on male rat sexual behavior

The role of cholinergic neurotransmission in male rat sexual behavior at the brain level has been studied by several researchers. However, little is known about its role at the spinal cord level. In this study, the effects of the intrathecal (IT) administration of the muscarinic receptor antagonist subtypes (MRAs) methoctramine (Meth), tropicamide (Trop) and 4-DAMP on male rat sexual behavior were evaluated during three ejaculatory series. Meth and Trop are preferring antagonists for the M2/M4 receptor subtypes, and 4-DAMP is a preferring antagonist for the M3 receptor subtype. All the MRAs tested noticeably inhibited male rat copulatory behavior, reflected by a reduction in the number of animals engaging in sexual behavior and a gradual decrease in the number of animals able to ejaculate. Significant increases in intromission latency (IL), ejaculation latency (EL) and post-ejaculatory interval (PEI) were observed. The ranking of inhibitory potency in all recorded parameters was Meth>/=4-DAMP>Trop. In theory, the effects of Meth and Trop could be a result of interaction with M2/M4 receptors. However, given that the M2 receptor constitutes the greatest population of muscarinic receptors at all spinal cord sites and given the high affinity for Meth on M2 receptors, the high potency in the inhibitory effects of Meth is indicative of the special role of M2 spinal receptors in the implementation of this behavior. The weaker effects of Trop could be linked to the smaller population of M4 receptors in the spinal cord, but some interaction with M2 receptors is probable. Since some differences in the pattern of inhibitory response between Meth and 4-DAMP were observed in this and a previous study, a possible role for M3 receptors must be considered. The data obtained in this study confirm the facilitating effect of acetylcholine (ACh) at the spinal cord level on male rat sexual behavior through muscarinic mechanisms, with an important influence on ejaculatory processes. These data support the hypothesis of the modulating role of ACh on male rat sexual behavior at the spinal cord level.

Peripheral bee venom's anti-inflammatory effect involves activation of the coeruleospinal pathway and sympathetic preganglionic neurons

There are several reports indicating that the locus coeruleus (LC) is capable of altering immune responses. Moreover, it is well established that the LC is the major source of descending noradrenergic system. Recently we have demonstrated that subcutaneous bee venom (BV) injection dramatically suppressed peripheral inflammation through activation of sympathetic preganglionic neurons (SPNs) leading to release of adreno-medullary catecholamines. Importantly, this 'BV-induced anti-inflammatory effect' (BVAI) is also associated with an increase of the activity of LC. Based on these data, present study examined whether BV-induced LC activation increased the activity of SPNs and this pathway played a role in BVAI using a zymosan-induced inflammatory air pouch model in mice. Unilateral BV injection into left hind limb produced anti-inflammation and specifically increased Fos expression in SPNs of the T7-T11 (which mainly project to adrenal medulla), but not those of the T1-T6 or T12-L2 spinal cord. 6-Hydroxydopamine-induced unilateral lesion of the contralateral, but not ipsilateral (to the BV injection site) LC significantly blocked BVAI and BV-induced Fos expression in SPNs. Additionally, intrathecal administration of idazoxan (alpha2-adrenoceptor antagonist), blocked BVAI. These results indicate that BV-induced activation of the contralateral LC-descending noradrenergic pathway increased the activity of SPNs that project to the adrenal medulla and this pathway is necessary for BVAI.

Transient suppression of the vesicular acetylcholine transporter in urinary bladder pathways following spinal cord injury

The aim of this study was to examine the expression profile of the vesicular acetylcholine transporter (VAChT), which is a cholinergic pre-synaptic marker, in the lower neural tract following spinal cord injury (SCI) and its effect on coordination of micturition. In adult female Sprague-Dawley rats, SCI was induced by complete transection of the spinal cord at T9. At various time points, 3, 7, 14 and 28 days, after SCI, cystometry was performed on conscious rats. Bladder areflexia was observed during the first week. Twenty-eight days after SCI the rats showed reflex contractions and voiding. The expression of VAChT was examined with immunohistochemistry. The number of VAChT-positive nerve terminals, which were surrounding neuronal soma, was transiently decreased in pelvic ganglion and spinal cord (L1, L2, L6 and S1). In particular VAChT terminals surrounding motor neurons in the ventral horn and autonomic pre-ganglion cells were dramatically decreased from 3 to 14 days after SCI. Similarly, and the number of VAChT-positive fibers in the bladder wall was also decreased. The intensity of VAChT terminals recovered in all above regions in conjunction with recovery of bladder function. These observations indicate that the transient decrease of the VAChT-positive nerve might cause a failure of cholinergic neuronal transmission along the urinary bladder tract after SCI. As the cholinergic system was recovered at least in rat, the functional recovery of neurogenic bladder syndrome in SCI patients may become possible by further understanding the mechanism underlying the recovery of cholinergic system in rat.

Androgens regulate the sexually dimorphic production of co-contained galanin and cholecystokinin in lumbar laminae VII and X neurons

A population of rat lumbar laminae VII and X putative spinothalamic (STT) neurons that co-contain cholecystokinin-8 (CCK) and galanin (GAL) are sexually dimorphic. Males have a significantly greater number of these neurons, as well as having greater optical densities for both neuropeptides than females. Optical densities for GAL and CCK immunoreactivities in these lumbar neurons in rats that have the testicular feminization mutation (Tfm) are not significantly different from females; however, the number of these lumbar neurons in Tfm rats is significantly smaller than in females. These data suggest that androgens, as well as functional androgen receptors (that Tfm rats lack), are necessary for the establishment of these sexual dimorphisms. Functionally, these CCK- and GAL-containing neurons in the deep lumbar laminae may contribute to the establishment of known sex differences in the affective component of somatic and visceral nociception, as well as the sexually dimorphic nature of some pelvic diseases, e.g., irritable bowel syndrome or cystitis.

Sympathetic genital responses induced by p-chloroamphetamine in anaesthetized female rats

In urethane-anesthetized female rats, a branch of the hypogastric nerve equivalent to the vas deferens nerve in males was shown anatomically and electrophysiologically to supply the uterine horns and we have consequently termed this the uterine nerve. Administration of p-chloroamphetamine i.v. elicited patterned bursting uterine nerve activity responses together with contractions of the uterine horns and musculature of the vaginal wall. These responses are qualitatively similar to ejaculatory responses observed following p-chloroamphetamine administration to anesthetized male rats and the urethrogenital reflex in females, suggesting they represent responses occurring during sexual processes. This response to p-chloroamphetamine was still present after complete transection of the spinal cord at T8. These data indicate that common neurophysiological and pharmacological mechanisms regulate genital reflexes at the lumbosacral spinal level in both the female and the male rat.

Identification of lumbar spinal neurons controlling simultaneously the prostate and the bulbospongiosus muscles in the rat

Lumbar spinothalamic neurons in the lamina X of the L3-L4 spinal cord segment have been proposed to constitute the spinal ejaculation generator in male rats. Lumbar spinothalamic cells are immunoreactive for galanin and neurokinin-1 receptors. We previously showed that after injection of pseudorabies virus either in the bulbospongiosus muscle or in the prostate, retrogradely labeled cells in the L3-L4 segment also displayed galanin or neurokinin-1 receptor immunoreactivities, demonstrating a direct link between lumbar spinothalamic cells and two anatomical structures involved in the two phases of ejaculation i.e. the emission and the expulsion phases. In order to provide with a more precise anatomical support for the role of lumbar spinothalamic cells in controlling ejaculation, we injected simultaneously in male adult rats two strains of recombinant pseudorabies virus, expressing either beta-galactosidase (PRV-BaBlu) or green fluorescent protein (PRV-152) in the prostate and in the bulbospongiosus muscle, respectively. After 5 days, we performed multiple immunofluorescence experiments to detect PRV-BaBlu, PRV-152 and galanin or neurokinin-1 receptors in transverse sections of the L1-S1 segment. Double- and triple-labeled cells were counted using confocal laser scanning microscope. Double-labeled neurons with the two strains of pseudorabies virus were mainly found at the L3-L4 segment lateral to the central canal in lamina X and represented about 60% of the total number of pseudorabies virus-labeled neurons. All the double pseudorabies virus-labeled neurons also expressed lumbar spinothalamic and most of them neurokinin-1 receptor, identifying them as lumbar spinothalamic neurons. The convergence of retrograde labeling from prostate and bulbospongiosus muscle on the same lumbar spinothalamic cells strongly reinforce their role in the spinal control and coordination of the emission and expulsion of sperm.

Descending pathways modulating the spinal circuitry for ejaculation: effects of chronic spinal cord injury

Sexual dysfunction is a common complication in men with chronic spinal cord injury. In particular, ejaculation is severely compromised or absent and the resulting infertility issues are important to this group of predominantly young men. To investigate the neural circuits and descending spinal pathways involved in ejaculation, animal models have been developed in normal and spinal cord-injured preparations. Primarily through studies in rats, spinal ejaculatory circuits have been described including (i) autonomic circuits at the thoracolumbar and lumbosacral levels mediating the emission phase of ejaculation, (ii) somatic circuits at the lumbosacral level controlling the expulsion phase of ejaculation through sequential and rhythmic contraction of perineal striated muscles (e.g. bulbospongiosus), and (iii) a proposed ejaculatory pattern generator in the lumbar cord. Midthoracic incomplete chronic spinal cord injury has revealed the dependency of spinal ejaculatory circuits on bilateral spinal pathways from the brainstem via modulation of pudendal motor neuron reflexes and pudendal nerve autonomic fibers. Accordingly, sensory input from the dorsal nerve of the penis, required to trigger the ejaculatory response in animals and humans, is no longer inhibited from the lateral paragigantocellularis nucleus in the ventrolateral medulla. This inhibitory effect, likely presynaptic through a serotonergic pathway, is thought to be necessary to provide the rhythmic, bursting, and sequential contractions of the perineal muscles during ejaculation. Chronic lateral hemisection injury, which severs half of the descending lateral funiculus-located pathways, results in new functional connections of the pudendal reflex inhibitory and pudendal sympathetic activation pathways across the midline, above and below the lesion, respectively. Clinical correlations in spinal cord-injured men have demonstrated the validity of the rodent animal for the study of ejaculatory dysfunction after chronic injury.

Activation by p-chloroamphetamine of the spinal ejaculatory pattern generator in anaesthetized male rats

In urethane-anesthetized male rats, a branch of the hypogastric nerve was shown, anatomically and electrophysiologically, to supply the vas deferens. Recordings from this nerve revealed a low level of tonic activity, which was predominantly efferent motor activity. Administration of p-chloroamphetamine i.v., elicited a rhythmic burst of neuronal activity, coherent with rhythmic pressure increases in the vas deferens and contractions of the bulbospongiosus muscles, which together comprise ejaculation. This response to p-chloroamphetamine was still present after complete transection of the spinal cord at T8-T9. These data indicate that p-chloroamphetamine is capable of activating the spinal neuronal circuits that generate the pattern of autonomic and somatic responses similar to those of sexual climax. Furthermore based on the best documented action of p-chloroamphetamine, the results suggest that the excitability of the pattern generator is regulated by serotonergic, dopaminergic or noradrenergic receptors in the lumbosacral spinal cord. We conclude this animal model will enable robust studies of the pharmacology and physiology of central neural mechanisms involved in ejaculation and sexual climax.

The anti-inflammatory effect of peripheral bee venom stimulation is mediated by central muscarinic type 2 receptors and activation of sympathetic preganglionic neurons

The anti-inflammatory effect (AI) induced by peripheral injection of diluted bee venom (dBV) involves activation of spinal cord circuits and is mediated by catecholamine release from adrenal medulla, but the precise neuronal mechanisms involved are not fully understood. In a recent study, we demonstrated that an increase in spinal acetylcholine is involved in mediating the anti-inflammatory effect of dBV and that this mediation also involves adrenomedullary activation. The present study utilized the mouse air pouch inflammation model to evaluate the involvement of spinal acetylcholine receptors and sympathetic preganglionic neurons (SPNs) in dBV's anti-inflammatory effect (dBVAI). Intrathecal (IT) pretreatment with atropine (muscarinic cholinergic antagonist) but not hexamethonium (nicotinic cholinergic antagonist) significantly suppressed dBVAI on zymosan-evoked leukocyte migration. Subsequent experiments showed that IT pretreatment with methoctramine (a muscarinic receptor type 2; M(2) antagonist), but not pirenzepine (an M(1) antagonist) or 4-DAMP (an M(3) antagonist), suppressed the dBVAI. In addition, dBV stimulation specifically increased Fos expression in SPNs of the T7-T11, but not the T1-T6 or T12-L2 spinal cord segments, in animals with zymosan-induced inflammation. Moreover, IT methoctramine pretreatment suppressed this dBV-induced Fos expression specifically in SPNs of T7-T11 level. Peripheral sympathetic denervation using 6-hydroxydopamine (6-OHDA) treatment (which spares sympathetic adrenal medullary innervation) did not alter dBVAI. Collectively these results indicate that dBV stimulation leads to spinal cord acetylcholine release that in turn acts on spinal M(2) receptors, which via a hypothesized disinhibition mechanism activates SPNs that project to the adrenal medulla. This activation ultimately leads to the release of adrenal catecholamines that contribute to dBVAI.