Mapping of neurokinin-like immunoreactivity in the human brainstem

Organ- and function-specific anatomical organization of vagal fibers supports fascicular vagus nerve stimulation

Vagal fibers travel inside fascicles and form branches to innervate organs and regulate organ functions. Existing vagus nerve stimulation (VNS) therapies activate vagal fibers non-selectively, often resulting in reduced efficacy and side effects from non-targeted organs. The transverse and longitudinal arrangement of fibers inside the vagal trunk with respect to the functions they mediate and organs they innervate is unknown, however it is crucial for selective VNS. Using micro-computed tomography imaging, we tracked fascicular trajectories and found that, in swine, sensory and motor fascicles are spatially separated cephalad, close to the nodose ganglion, and merge caudad, towards the lower cervical and upper thoracic region; larynx-, heart- and lung-specific fascicles are separated caudad and progressively merge cephalad. Using quantified immunohistochemistry at single fiber level, we identified and characterized all vagal fibers and found that fibers of different morphological types are differentially distributed in fascicles: myelinated afferents and efferents occupy separate fascicles, myelinated and unmyelinated efferents also occupy separate fascicles, and small unmyelinated afferents are widely distributed within most fascicles. We developed a multi-contact cuff electrode to accommodate the fascicular structure of the vagal trunk and used it to deliver fascicle-selective cervical VNS in anesthetized and awake swine. Compound action potentials from distinct fiber types, and physiological responses from different organs, including laryngeal muscle, cough, breathing, and heart rate responses are elicited in a radially asymmetric manner, with consistent angular separations that agree with the documented fascicular organization. These results indicate that fibers in the trunk of the vagus nerve are anatomically organized according to functions they mediate and organs they innervate and can be asymmetrically activated by fascicular cervical VNS.

Mapping of folic acid in the children brainstem

Using highly specific antisera, the neuroanatomical distribution of folic acid (FA) and retinoic acid (RA) has been studied for the first time in the children brainstem. Neither immunoreactive structures containing RA nor immunoreactive fibers containing FA were found. FA-immunoreactive perikarya (fusiform, small/medium in size, one short dendrite) were only found in the pons in three regions: central gray, reticular formation, and locus coeruleus. The number of cell bodies decreased with age. In the first case studied (2 years), a moderate density of cell bodies was observed in the central gray and reticular formation, whereas a low density was found in the locus coeruleus. In the second case (6 years), a low density of these perikarya was observed in the central gray, reticular formation, and locus coeruleus. In the third case (7 years), a low density of FA-immunoreactive cell bodies was found in the central gray and reticular formation, whereas in the locus coeruleus no immunoreactive cell bodies were observed. The distribution of FA in the central nervous system of humans and monkeys is different and, in addition, in these species the vitamin was located in different parts of the nerve cells. The restricted distribution of FA suggests that the vitamin is involved in specific physiological mechanisms.

Neurokinin receptor antagonism: a patent review (2014-present)

INTRODUCTION

The tachykinin family of peptides (substance P, neurokinin A) via the neurokinin-1 (NK-1), NK-2, and NK-3 receptors is involved in many physiological/physiopathological actions. Antagonists of these receptors may be used to treat many human pathologies.

AREAS COVERED

This review offers an overview (from 2014 to present) of the actions exerted by NK receptor (NK-R) antagonists on emesis, pruritus, cardiomyopathy, respiratory tract diseases, bacterial infection, cancer, ocular pain, corneal neovascularization, excess of body fat/weight, conditioned fear, social isolation stress, hot flush, melanogenesis, follicle development, fish reproduction, and sex-hormone-dependent diseases.

EXPERT OPINION

From 2014, no invention has been published using NK-2R antagonists. Although the tachykinin/NK receptor system is involved in a great number of mechanisms, to date, the use of only five NK-1R antagonists have been approved in humans but no NK-2R or NK-3R antagonist. NK receptor antagonists are safe in human trials and are potential therapeutic agents, but this potential is currently minimized. In humans, more studies on molecules acting as NK receptor antagonists and exerting a potential therapeutic action must be carried out. The antipruritic or antitumor action of NK-1R antagonists must be explored in greater depth: the highest safe dose and the time of administration (for a long period of time) of these antagonists must be well established.

Neuroanatomical relationship between the cholinergic and tachykininergic systems in the adult human brainstem: An immunohistochemical study

The cholinergic system plays an important role in brain homeostasis and interacts with the neuropeptidergic systems, and the functional relationships between both systems are well known. However, in the brainstem the possible physiological interactions between neurokinins and acetylcholine are unknown, although both substances have been detected in the same brainstem nuclei and have been implicated in similar functions controlled from brainstem regions such as some cranial motor nuclei. The aim of this work is to determine whether these possible physiological interactions might have a neuroanatomical basis by means of the double immunohistochemical detection of neurokinins (NK) and the enzyme choline acetyl-transferase (ChAT) in the human brainstem. No double-labelled structures were detected, although both NK and ChAT were observed in cell bodies and fibers of the same brainstem nuclei. The distribution of immunoreactive fibers is widespread, and NK and ChAT were observed in several motor cranial nerves as well as in the substantia nigra. The results obtained in the present work provide a neuroanatomical basis for possible physiological interactions between NK and ChAT that may be carried out by volume-transmission mechanisms. These interactions might participate in motor regulation or in limbic pathways as well as influence on other neurotransmitter systems such as the dopaminergic system.

Perfusion fixation in brain banking: a systematic review

Background

Perfusing fixatives through the cerebrovascular system is the gold standard approach in animals to prepare brain tissue for spatial biomolecular profiling, circuit tracing, and ultrastructural studies such as connectomics. Translating these discoveries to humans requires examination of postmortem autopsy brain tissue. Yet banked brain tissue is routinely prepared using immersion fixation, which is a significant barrier to optimal preservation of tissue architecture. The challenges involved in adopting perfusion fixation in brain banks and the extent to which it improves histology quality are not well defined.

Methodology

We searched four databases to identify studies that have performed perfusion fixation in human brain tissue and screened the references of the eligible studies to identify further studies. From the included studies, we extracted data about the methods that they used, as well as any data comparing perfusion fixation to immersion fixation. The protocol was preregistered at the Open Science Framework: https://osf.io/cv3ys/.

Results

We screened 4489 abstracts, 214 full-text publications, and identified 35 studies that met our inclusion criteria, which collectively reported on the perfusion fixation of 558 human brains. We identified a wide variety of approaches to perfusion fixation, including perfusion fixation of the brain in situ and ex situ, perfusion fixation through different sets of blood vessels, and perfusion fixation with different washout solutions, fixatives, perfusion pressures, and postfixation tissue processing methods. Through a qualitative synthesis of data comparing the outcomes of perfusion and immersion fixation, we found moderate confidence evidence showing that perfusion fixation results in equal or greater subjective histology quality compared to immersion fixation of relatively large volumes of brain tissue, in an equal or shorter amount of time.

Conclusions

This manuscript serves as a resource for investigators interested in building upon the methods and results of previous research in designing their own perfusion fixation studies in human brains or other large animal brains. We also suggest several future research directions, such as comparing the in situ and ex situ approaches to perfusion fixation, studying the efficacy of different washout solutions, and elucidating the types of brain donors in which perfusion fixation is likely to result in higher fixation quality than immersion fixation.

Electronic supplementary material

The online version of this article (10.1186/s40478-019-0799-y) contains supplementary material, which is available to authorized users.

Breathing matters

Breathing is a well-described, vital and surprisingly complex behaviour, with behavioural and physiological outputs that are easy to directly measure. Key neural elements for generating breathing pattern are distinct, compact and form a network amenable to detailed interrogation, promising the imminent discovery of molecular, cellular, synaptic and network mechanisms that give rise to the behaviour. Coupled oscillatory microcircuits make up the rhythmic core of the breathing network. Primary among these is the preBötzinger Complex (preBötC), which is composed of excitatory rhythmogenic interneurons and excitatory and inhibitory pattern-forming interneurons that together produce the essential periodic drive for inspiration. The preBötC coordinates all phases of the breathing cycle, coordinates breathing with orofacial behaviours and strongly influences, and is influenced by, emotion and cognition. Here, we review progress towards cracking the inner workings of this vital core.

The potential role of substance P in brainstem homeostatic control in the pathogenesis of sudden infant death syndrome (SIDS)

Victims of sudden infant death syndrome (SIDS) are believed to have an underlying dysfunction in medullary homeostatic control that impairs critical responses to life threatening challenges such as hypoxia, hypercarbia and asphyxia, often during a sleep period. This failure is thought to result from abnormalities in a network of neural pathways in the medulla oblongata that control respiration, chemosensitivity, autonomic function and arousal. Studies have mainly focused on the role of serotonin, 5-hydroxytyptamine (5HT), although the neuropeptide substance P (SP) has also been shown to play an integral role in the modulation of medullary homeostatic function, often in conjunction with 5-HT. Actions of SP include regulation of respiratory rhythm generation, integration of cardiovascular control, modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may, therefore, also play a significant role in homeostatic dysfunction of the neurotransmitter network in SIDS. This review focuses on the pathways within the medulla involving SP and its tachykinin NK1 receptor, their potential relationship with the medullary 5-HT system, and possible involvement in the pathogenesis of SIDS.

TRPV1-Like Immunoreactivity in the Human Locus K, a Distinct Subregion of the Cuneate Nucleus

The presence of transient receptor potential vanilloid type-1 receptor (TRPV1)-like immunoreactivity (LI), in the form of nerve fibres and terminals, is shown in a set of discrete gray matter subregions placed in the territory of the human cuneate nucleus. We showed previously that those subregions share neurochemical and structural features with the protopathic nuclei and, after the ancient name of our town, collectively call them Locus Karalis, and briefly Locus K. TRPV1-LI in the Locus K is codistributed, though not perfectly overlapped, with that of the neuropeptides calcitonin gene-related peptide and substance P, the topography of the elements immunoreactive to the three markers, in relation to each other, reflecting that previously described in the caudal spinal trigeminal nucleus. Myelin stainings show that myelinated fibres, abundant in the cuneate, gracile and trigeminal magnocellular nuclei, are scarce in the Locus K as in the trigeminal substantia gelatinosa. Morphometric analysis shows that cell size and density of Locus K neurons are consistent with those of the trigeminal substantia gelatinosa and significantly different from those of the magnocellular trigeminal, solitary and dorsal column nuclei. We propose that Locus K is a special component of the human dorsal column nuclei. Its functional role remains to be determined, but TRPV1 appears to play a part in it.

Normative distribution of substance P and its tachykinin neurokinin-1 receptor in the medullary serotonergic network of the human infant during postnatal development

Substance P (SP) and its tachykinin NK1 receptor (NK1R) function within key medullary nuclei to regulate cardiorespiratory and autonomic control. We examined the normative distribution of SP and NK1R in the serotonergic (5-Hydroxytryptamine, [5-HT]) network of the human infant medulla during postnatal development, to provide a baseline to facilitate future analysis of the SP/NK1R system and its interaction with 5-HT within pediatric brainstem disorders in early life. [¹²⁵I] labelled Bolton Hunter SP (BH-SP) tissue receptor autoradiography (n = 15), single label immunohistochemistry (IHC) and double label immunofluorescence (IF) (n = 10) were used to characterize the normative distribution profile of SP and NK1R in the 5-HT network of the human infant medulla during postnatal development. Tissue receptor autoradiography revealed extensive distribution of SP and NK1R in nuclei intimately related to cardiorespiratory function and autonomic control, with significant co-distribution and co-localization with 5-HT in the medullary network in the normal human infant during development. A trend for NK1R binding to decrease with age was observed with significantly higher binding in premature and male infants. We provide further evidence to suggest a significant role for SP/NK1R in the early postnatal period in the modulation of medullary cardiorespiratory and autonomic control in conjunction with medullary 5-HT mediated pathways and provide a baseline for future analysis of the potential consequences of abnormalities in these brainstem neurotransmitter networks during development.

Mapping of somatostatin-28 (1-12) in the alpaca (Lama pacos) brainstem

Using an indirect immunoperoxidase technique, we studied the distribution of cell bodies and fibers containing somatostatin-28 (1-12) in the alpaca brainstem. Immunoreactive fibers were widely distributed throughout the whole brainstem: 34 brainstem nuclei/regions showed a high or a moderate density of these fibers. Perikarya containing the peptide were widely distributed throughout the mesencephalon, pons and medulla oblongata. Cell bodies containing somatostatin-28 (1-12) were observed in the lateral and medial divisions of the marginal nucleus of the brachium conjunctivum, reticular formation (mesencephalon, pons and medulla oblongata), inferior colliculus, periaqueductal gray, superior colliculus, pericentral division of the dorsal tegmental nucleus, interpeduncular nucleus, nucleus of the trapezoid body, vestibular nucleus, motor dorsal nucleus of the vagus, nucleus of the solitary tract, nucleus praepositus hypoglossi, and in the substantia nigra. This widespread distribution indicates that somatostatin-28 (1-12) is involved in multiple physiological actions in the alpaca brainstem.

Tachykinin: recent developments and novel roles in health and disease

Over 80 years has passed since the discovery of substance P (SP), and a variety of peptides of the tachykinin (TK) family have been found and investigated. SP, neurokinin A (NKA), and neurokinin B (NKB) are representative peptides in mammalian species. SP and NKA are major excitatory neurotransmitters in the peripheral nervous system, while NKB is primarily involved in the central nervous system (CNS). Moreover, TK peptides play roles not only as neurotransmitters but also as local factors and are involved in almost all aspects of the regulation of physiological functions and pathophysiological processes. The role of SP as a mediator of pain processing and inflammation in peripheral tissues in coordination with transient receptor potential channels is well established, while novel aspects of TKs in relation to hematopoiesis, venous thromboembolism, tendinopathy, and taste perception have been clarified. In the CNS, the NKB signaling system in the hypothalamus has been shown to play a crucial role in the regulation of gonadotropin hormone secretion and the onset of puberty, and molecular biological studies have elucidated novel prophylaxic activities of TKs against neurogenic movement disorders based on their molecular structure. This review provides an overview of the novel aspects of TKs reported around the world in the last 5 years, with particular focus on nociception, inflammation, hemopoiesis, gonadotropin secretion, and CNS diseases.

New therapies in the treatment of overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a common condition which affects both men and women across many age groups with significant impact on quality of life. There is currently an armamentarium of treatment options available ranging from conservative, medical therapy to radical surgeries. Increasing understanding of OAB is resulting in the rapid development of new therapies today.

AREAS COVERED

The purpose of this article was to summarise the latest developments in non-neurogenic OAB treatment, discuss the evidence and results of current and new treatment modalities available through review of published data and results presented at recent international meetings.

EXPERT OPINION

The ultimate goal in OAB therapy is to provide good clinical efficacy, safe, non-invasive and easy to administer. There is definitely room for development of new therapies in OAB and current progress is encouraging.

Sex differences in the neurokinin B system in the human infundibular nucleus

CONTEXT

The recent report that loss-of-function mutations in either the gene encoding neurokinin B (NKB) or its receptor (NK3R) produce gonadotropin deficiencies in humans strongly points to NKB as a key regulator of GnRH release.

OBJECTIVES

We used NKB immunohistochemistry on postmortem human brain tissue to determine: 1) whether the human NKB system in the infundibular nucleus (INF) is sexually dimorphic; 2) at what stage in development the infundibular NKB system would diverge between men and women; 3) whether this putative structural difference is reversed in male-to-female (MtF) transsexual people; and 4) whether menopause is accompanied by changes in infundibular NKB immunoreactivity.

METHODS

NKB immunohistochemical staining was performed on postmortem hypothalamus material of both sexes from the infant/pubertal period into the elderly period and from MtF transsexuals.

RESULTS

Quantitative analysis demonstrated that the human NKB system exhibits a robust female-dominant sexual dimorphism in the INF. During the first years after birth, both sexes displayed a moderate and equivalent level of NKB immunoreactivity in the INF. The adult features emerged progressively around puberty until adulthood, where the female-dominant sex difference appeared and continued into old age. In MtF transsexuals, a female-typical NKB immunoreactivity was observed. Finally, in postmenopausal women, there was a significant increase in NKB immunoreactivity compared to premenopausal women.

CONCLUSION

Our results indicate that certain sex differences do not emerge until adulthood when activated by sex steroid hormones and the likely involvement of the human infundibular NKB system in the negative and positive feedback of estrogen on GnRH secretion.

Mapping of alpha-neo-endorphin- and neurokinin B-immunoreactivity in the human brainstem

We have studied the distribution of alpha-neo-endorphin- or neurokinin B-immunoreactive fibres and cell bodies in the adult human brainstem with no prior history of neurological or psychiatric disease. A low density of alpha-neo-endorphin-immunoreactive cell bodies was only observed in the medullary central gray matter and in the spinal trigeminal nucleus (gelatinosa part). Alpha-neo-endorphin-immunoreactive fibres were moderately distributed throughout the human brainstem. A high density of alpha-neo-endorphin-immunoreactive fibres was found only in the solitary nucleus (caudal part), in the spinal trigeminal nucleus (caudal part), and in the gelatinosa part of the latter nucleus. Neurokinin B-immunoreactive cell bodies (low density) were found in the periventricular central gray matter, the reticular formation of the pons and in the superior colliculus. The distribution of the neurokinin-immunoreactive fibres was restricted. In general, for both neuropeptides the density of the immunoreactive fibres was low. In the human brainstem, the proenkephalin system was more widely distributed than the prodynorphin system, and the preprotachykinin A system (neurokinin A) was more widely distributed than the preprotachykinin B system (neurokinin B).

Chronic intermittent hypoxia reduces neurokinin-1 (NK(1)) receptor density in small dendrites of non-catecholaminergic neurons in mouse nucleus tractus solitarius

Chronic intermittent hypoxia (CIH) is a frequent concomitant of sleep apnea, which can increase sympathetic nerve activity through mechanisms involving chemoreceptor inputs to the commissural nucleus of the solitary tract (cNTS). These chemosensory inputs co-store glutamate and substance P (SP), an endogenous ligand for neurokinin-1 (NK(1)) receptors. Acute hypoxia results in internalization of NK(1) receptors, suggesting that CIH also may affect the subcellular distribution of NK(1) receptors in subpopulations of cNTS neurons, some of which may express tyrosine hydroxylase, the rate-limiting enzyme for catecholamine synthesis (TH). To test this hypothesis, we examined dual immunolabeling for the NK(1) receptor and TH in the cNTS of male mice subjected to 10days or 35days of CIH or intermittent air. Electron microscopy revealed that NK(1) receptors and TH were almost exclusively localized within separate somatodendritic profiles in cNTS of control mice. In dendrites, immunogold particles identifying NK(1) receptors were prevalent in the cytoplasm and on the plasmalemmal surface. Compared with controls, CIH produced a significant region-specific decrease in the cytoplasmic (10 and 35days, P<0.05, unpaired Student t-test) and extrasynaptic plasmalemmal (35days, P<0.01, unpaired Student t-test) density of NK(1) immunogold particles exclusively in small (<0.1microm) dendrites without TH immunoreactivity. These results suggest that CIH produces a duration-dependent reduction in the availability of NK(1) receptors preferentially in small dendrites of non-catecholaminergic neurons in the cNTS. The implications of our findings are discussed with respect to their potential involvement in the slowly developing hypertension seen in sleep apnea patients.

Prospective pharmacologic therapies for the overactive bladder

Lower urinary tract symptoms (LUTS), overactive bladder syndrome (OAB) and detrusor overactivity (DO) are all conditions that can have major effects on quality of life and social functioning. Antimuscarinic drugs are first-line treatment-they often have good initial response rates, but adverse effects and decreasing efficacy cause long-term compliance problems, and alternatives are needed. The recognition of the functional contribution of the urothelium, the spontaneous myocyte activity during bladder filling, and the diversity of nerve transmitters has sparked interest in both peripheral and central modulation of LUTS/OAB/DO pathophysiology. There may be several new possibilities to treat LUTS/OAB/DO. β(3)-AR agonists (YM178), PDE 5 inhibitors (sildenafil, tadalafil, vardenafil), vitamin D analogs (elocalcitol), combinations (α(1)-AR antagonist + antimuscarinic), and drugs with a central mode of action (tramadol, aprepitant) all have Randomized controlled trial (RCT) documented efficacy. Which of these therapeutic principles will be developed to clinically useful treatments remains to be established.

Mapping of CGRP in the alpaca (Lama pacos) brainstem

In this study, we demonstrate the presence of immunoreactive structures containing calcitonin gene-related peptide in the alpaca brainstem. This is the first time that a detailed mapping of the cell bodies and fibers containing this neuropeptide in the alpaca brainstem has been carried out using an immunocytochemical technique. Immunoreactive cell bodies and fibers were widely distributed throughout the alpaca brainstem. A high density of calcitonin gene-related peptide-immunoreactive perikarya was found in the superior colliculus, the dorsal nucleus of the raphe, the trochlear nucleus, the lateral division of the marginal nucleus of the brachium conjunctivum, the motor trigeminal nucleus, the facial nucleus, the pons reticular formation, the retrofacial nucleus, the rostral hypoglossal nucleus, and in the motor dorsal nucleus of the vagus, whereas a high density of fibers containing calcitonin gene-related peptide was observed in the lateral division of the marginal nucleus of the brachium conjunctivum, the parvocellular division of the alaminar spinal trigeminal nucleus, the external cuneate nucleus, the nucleus of the solitary tract, the laminar spinal trigeminal nucleus, and in the area postrema. This widespread distribution indicates that the neuropeptide studied might be involved in multiple functions in the alpaca brainstem.

Administration of an antagonist of neurokinin receptors 1, 2, and 3 results in reproductive tract changes in beagle dogs, but not rats

SCH 206272, an antagonist of neurokinin receptors 1, 2, and 3, was administered orally by gavage for 1 month to 8- to 10-month-old dogs at doses of 0, 15, 30, or 60 mg/kg, and to 6-week-old rats at doses of 0, 30, 100, or 300 mg/kg. The most important changes occurred in the reproductive tract of the dogs at all doses. Absolute and relative group mean organ weights for the testes, prostate gland, epididymides, ovaries, and uterus were 33-86% lower than concurrent controls in groups receiving SCH 206272. Organ weight changes were not dose-related. Microscopic changes that correlated with the organ weight changes occurred in all groups receiving SCH 206272. For males, they included minimal to severe atrophy of the testes, epididymides, and prostate gland. In addition, the epididymides exhibited severe oligospermia or aspermia, minimal epithelial apoptosis and mild epithelial vacuolation. In female dogs, the ovaries and uteri appeared immature. Microscopic changes were similar in incidence and severity in dogs receiving 30 or 60 mg/kg, but were slightly less in dogs receiving 15 mg/kg. In contrast, similar findings were not observed in the reproductive tract of male or female rats, despite overlapping systemic, hypothalamic, and pituitary gland concentrations of SCH 206272.

Mapping of neurokinin b in the cat brainstem

We studied the distribution of neurokinin B-immunoreactive cell bodies and fibers in the cat brainstem using an indirect immunoperoxidase technique. The highest density of immunoreactive fibers was found in the motor trigeminal nucleus, the laminar and alaminar spinal trigeminal nuclei, the facial nucleus, the marginal nucleus of the brachium conjunctivum, the locus coeruleus, the cuneiform nucleus, the dorsal motor nucleus of the vagus, the postpyramidal nucleus of the raphe, the lateral tegmental field, the Kölliker-Fuse nucleus, the inferior central nucleus, the periaqueductal gray, the nucleus of the solitary tract, and in the inferior vestibular nucleus. Immunoreactive cell bodies containing neurokinin B were observed, for example, in the locus coeruleus, the dorsal motor nucleus of the vagus, the median division of the dorsal nucleus of the raphe, the lateral tegmental field, the pericentral nucleus of the inferior colliculus, the internal division of the lateral reticular nucleus, the inferior central nucleus, the periaqueductal gray, the postpyramidal nucleus of the raphe, and in the medial nucleus of the solitary tract. This widespread distribution of neurokinin B in the cat brainstem suggests that the neuropeptide could be involved in many different physiological functions. In comparison with previous studies carried out in the rat brainstem on the distribution of neurokinin B, our results point to a more widespread distribution of this neuropeptide in the cat brainstem.

Pharmacology of the lower urinary tract: basis for current and future treatments of urinary incontinence

The lower urinary tract constitutes a functional unit controlled by a complex interplay between the central and peripheral nervous systems and local regulatory factors. In the adult, micturition is controlled by a spinobulbospinal reflex, which is under suprapontine control. Several central nervous system transmitters can modulate voiding, as well as, potentially, drugs affecting voiding; for example, noradrenaline, GABA, or dopamine receptors and mechanisms may be therapeutically useful. Peripherally, lower urinary tract function is dependent on the concerted action of the smooth and striated muscles of the urinary bladder, urethra, and periurethral region. Various neurotransmitters, including acetylcholine, noradrenaline, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in this neural regulation. Muscarinic receptors mediate normal bladder contraction as well as at least the main part of contraction in the overactive bladder. Disorders of micturition can roughly be classified as disturbances of storage or disturbances of emptying. Failure to store urine may lead to various forms of incontinence, the main forms of which are urge and stress incontinence. The etiology and pathophysiology of these disorders remain incompletely known, which is reflected in the fact that current drug treatment includes a relatively small number of more or less well-documented alternatives. Antimuscarinics are the main-stay of pharmacological treatment of the overactive bladder syndrome, which is characterized by urgency, frequency, and urge incontinence. Accepted drug treatments of stress incontinence are currently scarce, but new alternatives are emerging. New targets for control of micturition are being defined, but further research is needed to advance the pharmacological treatment of micturition disorders.