Systematic Morphometry of Catecholamine Nuclei in the Brainstem

Abstract

Catecholamine nuclei within the brainstem reticular formation (RF) play a pivotal role in a variety of brain functions. However, a systematic characterization of these nuclei in the very same experimental conditions is missing so far. Tyrosine hydroxylase (TH) immune-positive cells of the brainstem correspond to dopamine (DA)-, norepinephrine (NE)-, and epinephrine (E)-containing cells. Here, we report a systematic count of TH-positive neurons in the RF of the mouse brainstem by using stereological morphometry. All these nuclei were analyzed for anatomical localization, rostro-caudal extension, volume, neuron number, neuron density, and mean neuronal area for each nucleus. The present data apart from inherent informative value wish to represent a reference for neuronal mapping in those studies investigating the functional anatomy of the brainstem RF. These include: the sleep-wake cycle, movement control, muscle tone modulation, mood control, novelty orienting stimuli, attention, archaic responses to internal and external stressful stimuli, anxiety, breathing, blood pressure, and innumerable activities modulated by the archaic iso-dendritic hard core of the brainstem RF. Most TH-immune-positive cells fill the lateral part of the RF, which indeed possesses a high catecholamine content. A few nuclei are medial, although conventional nosography considers all these nuclei as part of the lateral column of the RF. Despite the key role of these nuclei in psychiatric and neurological disorders, only a few of them aspired a great attention in biomedical investigation, while most of them remain largely obscure although intense research is currently in progress. A simultaneous description of all these nuclei is not simply key to comprehend the variety of brainstem catecholamine reticular neurons, but probably represents an intrinsically key base for understanding brain physiology and physiopathology.

The Effects of Amphetamine and Methamphetamine on the Release of Norepinephrine, Dopamine and Acetylcholine From the Brainstem Reticular Formation

“…Catecholamine-containing nuclei are mainly housed within the lateral extent of the RF (Figure 2). A very recent original manuscript provided stereological morphometry data encompassing all brainstem reticular catecholamine nuclei at one glance (Bucci et al, 2017). These include NE neurons of the pons and medulla, which were identified by using TH immunostaining (Bucci et al, 2017).…”

“…A very recent original manuscript provided stereological morphometry data encompassing all brainstem reticular catecholamine nuclei at one glance (Bucci et al, 2017). These include NE neurons of the pons and medulla, which were identified by using TH immunostaining (Bucci et al, 2017). For this reason, we will refer to NE-containing nuclei and we will include the E-related sub-nuclei as a putative attribute, since most of them are believed to represent a continuum with NE areas.…”

“…In detail, most monoamine-containing nuclei of the ponto-medullary RF are placed in a quite restricted brain region corresponding to the median and lateral column of the RF of the brainstem. The basis for both short- and long-term behavioral, motor and vegetative effects of AMPHs stems from such a selective uptake and common intracellular targets of AMPHs within these monoamine-containing neurons (Bucci et al, 2017). These neurons produce widespread innervation of a variety of limbic, motor and iso-cortical areas where ultimately the effects of AMPHs are produced.…”

“…Therefore, in the present review article, we avoid the analysis of DA neurons of the Substantia Nigra pars compacta (SNpc) and Ventral Tegmental Area (VTA), and focus instead on catecholamine nuclei of the low brainstem. In particular, we focus on NE nuclei located within the lateral column of the bulbo-pontine RF and a mixed neuronal population within the dorsal raphe/periaqueductal gray (PAG), which contains a subset of NE and DA neurons (Battenberg and Bloom, 1975; Saavedra et al, 1976; Steinbusch et al, 1981; Nieuwenhuys et al, 1988; Baker et al, 1990, 1991; Lu et al, 2006; Li et al, 2016; Bucci et al, 2017; Cho et al, 2017). We also overview cholinergic cells placed in the lateral column of the pontine RF, which extend up to the lateral wings of the dorsal raphe (Satoh et al, 1983; Nieuwenhuys et al, 2007; Vasudeva and Waterhouse, 2014; de Oliveira et al, 2016).…”

Editorial: The Anatomical Basis of the Cross Talk Between Immune System and Brain

“…This double innervation from the peripheral sympathetic nervous system grants the coordination of the blood flow with functional needs from rather large brain areas and it is substituted by a central innervation to tune focal brain sites which are nurtured by the smallest brain arteries. Such a central innervation within focal district is provided by norepinephrine-containing axons arising from a few nuclei of the brainstem, such as the locus coeruleus or the serotonin-containing axons arising from the dorsal raphe nucleus (Bucci et al, 2017). In this way, the paracrine effects induced by the release of these monoamines (Agnati et al, 1995;Agnati and Fuxe, 2000) may extend to the focal sites, which is responsible for the smallest neurovascular unit.…”