Distribution of histaminergic neuronal cluster in the rat and mouse hypothalamus

Abstract

Histidine decarboxylase (HDC) catalyzes the biosynthesis of histamine from L-histidine and is expressed throughout the mammalian nervous system by histaminergic neurons. Histaminergic neurons arise in the posterior mesencephalon during the early embryonic period and gradually develop into two histaminergic substreams around the lateral area of the posterior hypothalamus and the more anterior peri-cerebral aqueduct area before finally forming an adult-like pattern comprising five neuronal clusters, E1, E2, E3, E4, and E5, at the postnatal stage. This distribution of histaminergic neuronal clusters in the rat hypothalamus appears to be a consequence of neuronal development and reflects the functional differentiation within each neuronal cluster. However, the close linkage between the locations of histaminergic neuronal clusters and their physiological functions has yet to be fully elucidated because of the sparse information regarding the location and orientation of each histaminergic neuronal clusters in the hypothalamus of rats and mice. To clarify the distribution of the five-histaminergic neuronal clusters more clearly, we performed an immunohistochemical study using the anti-HDC antibody on serial sections of the rat hypothalamus according to the brain maps of rat and mouse. Our results confirmed that the HDC-immunoreactive (HDCi) neuronal clusters in the hypothalamus of rats and mice are observed in the ventrolateral part of the most posterior hypothalamus (E1), ventrolateral part of the posterior hypothalamus (E2), ventromedial part from the medial to the posterior hypothalamus (E3), periventricular part from the anterior to the medial hypothalamus (E4), and diffusely extended part of the more dorsal and almost entire hypothalamus (E5). The stereological estimation of the total number of HDCi neurons of each clusters revealed the larger amount of the rat than the mouse. The characterization of histaminergic neuronal clusters in the hypothalamus of rats and mice may provide useful information for further investigations.

Monoamines Inhibit GABAergic Neurons in Ventrolateral Preoptic Area That Make Direct Synaptic Connections to Hypothalamic Arousal Neurons

“…Figure 1C shows a typical example of the distribution of input neurons found in a representative mouse. In the rodent hypothalamus, HDC neurons are grouped into five clusters, E1-E5, each of which sends overlapping widespread projections throughout the brain (Ericson et al, 1987;Inagaki et al, 1990;Moriwaki et al, 2015). In our histological examinations, most starter neurons were found in the ventrolateral and ventromedial parts of the posterior hypothalamus, corresponding approximately to the E1 and E2 clusters, which have been shown to be involved in the regulation of arousal (Sakai et al, 2010; Umehara et al, 2012; Yu et al, 2015) (Fig.…”

Brain histamine modulates recognition memory: possible implications in major cognitive disorders

“…In rodents, a detailed mapping of TMN provided a subdivision of histaminergic neurons in distinct subpopulations. In the rat brain, histaminergic neuronal somata are grouped within the TMN in five clusters, E1–E5, each of which sends overlapping projections throughout the neuroaxis (Moriwaki et al ., 2015). A similar pattern of distribution has been reported in the brains of other mammals and non‐mammalian vertebrates (Sundvik and Panula, 2012; Wada et al ., 1991).…”

Dynamics of histological changes in histaminergic neurons of the rat hypothalamus in postnatal ontogenesis

“…В литературе описаны пространственно-временное структурирование гистаминергической системы в период эмбриогенеза [2,3], локализация, пространственная организация, строение, особенности метаболизма и функции гистаминергических нейронов гипоталамуса у взрослых животных в норме и при некоторых патологических состояниях [4,5]. Вместе с тем изучение развития этих нейронов в динамике постнатального онтогенеза не проводилось.…”