Distribution of histaminergic neuronal cluster in the rat and mouse hypothalamus.

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.

[Analysis of the clinical manifestations and electrophysiological changes in 32 patients with atypical myasthenia gravis].

OBJECTIVE: To study the clinical characteristics and electrophysiological changes in patients with atypical myasthenia gravis (MG). METHODS: The characteristics of the clinical symptoms and electrophysiological changes were investigated in 32 patients with atypical MG diagnosed in our hospital from January 2004 to December 2008. RESULTS: The ages of the patients ranged from 7 to 70 years. Five patients were diagnosed to have ocular MG (OMG), among whom 2 patient only complained of eye discomfort and blurred vision. Twenty-seven patients had generalized MG, and 6 of them showed muscle weakness of the limbs with or without mild difficulty in swallowing or respiratory muscles, but free of muscle dysfunctions in muscles of eyes, head, neck or face. Another 2 patients manifested muscular atrophy. Twenty-three patients (71.9%) displayed both fluctuating symptoms and positive results of fatigue test. Twenty-nine patients (90.6%) have positive results in the neostigmine test. Two patients in the OMG group (40.0%) showed positive results in the low frequency repetitive nerve stimulation (LFRNS), as compared with the 21 patients in the generalized MG group (71.9%) showing positive results. The total positivity rate of LFRNS was 71.9% in the total patients, consistent with the published data. CONCLUSIONS: In MG patients with atypical clinical symptoms, negative results of neostigmine test and fatigue test, LFRNS test can be an indispensable method to increase detection rate of MG and reduce erroneous or missed diagnosis.