Brain research bulletin
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Brain research bulletin · Jan 1995
Lesions in the medial posterior region of the BST impair sexual behavior in sexually experienced and inexperienced male rats.
Previous studies have showed that lesions in the bed nucleus of the stria terminalis of experienced male rats impair some parameters of sexual behavior. The aim of this study was to examine the contribution of the medial posterior region of the bed nucleus of the stria terminalis (BSTMP), a sexually dimorphic region of this nucleus that pertains to the vomeronasal system, to the modulation of sexual behavior of the male rat. Small electrolytic bilateral lesions in the BSTMP were made in male heterosexual experienced and inexperienced rats. ⋯ This group also showed low correlations between olfactory investigation of the anogenital area of the female and initiation and maintenance of copulatory behavior. The results suggest that sexual experience obtained in the very artificial conditions of laboratory tests could supply some of the cues provided by the BSTMP in the process of sensorial integration, which we hypothesize modulates the initiation and pacing of copulation. However, sexual experience does not apparently supply any other kinds of cues provided or processed in the BSTMP that are involved in modulating the elicitation of intromissions and ejaculations.
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The development of the folial pattern was studied in the cerebellar vermis of 32 trisomy 19 (Ts19) mice aged 1-16 days postpartum and their euploid littermates. In the Ts19 cerebellum, fissures were formed in the regular sequence observed in control littermates, but their appearance was delayed by about 2 days. Fissure number increased until day 6 in euploid controls and in Ts19 mice, remaining constant thereafter. ⋯ Both in Ts19 and control mice, a temporal and quantitative relationship was observed between fissure formation and the expansion of the external germinal layer, whereas the increase in fissure depth was found to correlate with the growth of the whole cerebellar vermis. Determination of the surface folding index revealed that only during fissure formation, the expansion of the cerebellar surface exceeded that of the cerebellar volume. The present study does not give any indication that foliation and histogenesis of the cerebellum are differentially affected by trisomy.
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Brain research bulletin · Feb 1991
Retrograde degeneration of nigrostriatal neurons induced by intrastriatal 6-hydroxydopamine injection in rats.
Quantitative receptor autoradiography was used to assess the effects of unilateral intrastriatal injections of 6-hydroxydopamine (6-OHDA) on the distribution of D1 and D2 dopamine (DA) receptors and of DA uptake sites in the mesostriatal pathway. [3H]Mazindol-labeled DA uptake sites were reduced both in the striatum (-97%) and in the substantia nigra pars compacta (SNpc) (-88%) on the injected side. There were also significant decreases of dopamine uptake sites in the nucleus accumbens (NAc) (-73%) and in the ventral tegmental area (VTA) (-70%). Changes in [3H]mazindol binding were also found within the contralateral VTA (-30%) and SNpc (-13%) but not in the contralateral-striatum. [3H]SCH23390-labeled D1 receptors were significantly reduced in the dorsomedial (-18%) and ventromedial (-14%) aspects of the striatum ipsilateral to the side of the lesions. ⋯ There were also significant decreases in D1 (-18%) and of D2 (-27%) receptors in the SNpc and of D1 (-10%) in the SN pars reticulata (SNpr). These results suggest that oxyradical-induced damage in striatal DA terminals could lead to retrograde changes in the SNpc. In addition, the data indicate that unilateral striatal damage can result in bilateral changes in the SNpc, thus confirming the interdependence of the two nigrostriatal pathways in rats.
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Brain research bulletin · Aug 1990
Gerbil hippocampal extracellular glutamate and neuronal activity after transient ischemia.
In order to elucidate the role of glutamate in the pathogenesis of delayed neuronal death, we analyzed changes in extracellular levels of glutamate induced by transient ischemia in the Mongolian gerbil hippocampus by a new brain microdialysis method combined with an enzymatic cycling technique. We also studied the effect of this change in glutamate on CA1 spontaneous neuronal discharges. The level of glutamate significantly increased during the 5 min of ischemia and during the first 5 min of recirculation. ⋯ However, the pattern of discharges was different from that recorded before the ischemia. CA1 neurons were found dead 4 days after the ischemia. Brief exposure to toxic concentrations of glutamate may cause the delayed neuronal death.
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Brain research bulletin · Apr 1990
Respiration-related neurons in the ventral medulla of newborn rats in vitro.
In brainstem-spinal cord preparations isolated from newborn rats, we examined functions of the ventral medulla in respiratory rhythm generation, and located respiratory neurons in that region. Removal of the dorsal half of the medulla caused only modest reduction of the rate of inspiratory bursts from the cervical (C4 or C5) ventral root and moderate changes in the burst pattern. We describe here two types of respiratory neurons; Pre-I neurons that are presumably crucial in primary rhythm generation, and inspiratory (I) neurons that we presume to be important in inspiratory pattern generation. ⋯ The results indicate that the ventral medulla is essential to inspiratory pattern generation as well as rhythm generation. It is suggested that the RVL is an important site in rhythm generation. The region of inspiratory pattern generation may extend more caudally in the ventral medulla.