The role of catecholaminergic neurons in the hypothalamus and medullary visceral zone in response to restraint water-immersion stress in rats
ABSTRACT The activity of catecholaminergic neurons in the hypothalamus and the medullary visceral zone (MVZ) in rats in response to restraint water-immersion stress (RWIS) was measured by use of dual Fos and tyrosine hydroxylase (TH) immunohistochemistry. In RWIS rats Fos immunoreactive (Fos-IR) nuclei dramatically increased in the paraventricular nucleus (PVN), the supraoptic nucleus (SON), the dorsal motor nucleus of the vagus (DMV), the nucleus of the solitary tract (NTS), the area postrema (AP), and the ventrolateral medulla (VLM). A small number of TH-immunoreactive (TH-IR) and Fos/TH double-labeling neurons in the PVN, and their absence from the SON, were observed in both RWIS and nonstressed rats. More TH-IR neurons were observed in the MVZ of RWIS rats than in nonstressed rats. In RWIS and nonstressed rats, the percentage of Fos-IR nuclei in TH-IR neurons was 38.0 and 14.3% in the DMV, 34.4 and 9.7% in the NTS, 18.6 and 4.5% in the AP, and 45.7 and 18.9% in the VLM, respectively. In conclusion, catecholaminergic neurons in the MVZ are involved in the response to RWIS; although the PVN and SON also participate in the response to RWIS, the mechanism is not via catecholaminergic neurons.
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ABSTRACT: Vasopressin (AVP) and oxytocin (OT) are considered to be related to gastric functions and the regulation of stress response. The present study was to study the role of vasopressinergic and oxytocinergic neurons during the restraint water-immersion stress. Ten male Wistar rats were divided into two groups, control and RWIS for 1h. The brain sections were treated with a dual immunohistochemistry of Fos and oxytocin (OT) or vasopressin (AVP) or OT receptor or AVP 1b receptor (V(1b)R). (1) Fos-immunoreactive (Fos-IR) neurons dramatically increased in the hypothalamic paraventricular nucleus (PVN), the supraoptic nucleus (SON), the nucleus of solitary tract (NTS) and motor nucleus of the vagus (DMV) in the RWIS rats; (2) OT-immunoreactive (OT-IR) neurons were mainly observed in the medial magnocellular part of the PVN and the dorsal portion of the SON, while AVP-immunoreactive (AVP-IR) neurons mainly distributed in the magnocellular part of the PVN and the ventral portion of the SON. In the RWIS rats, Fos-IR neurons were identified in 31% of OT-IR neurons and 40% of AVP-IR neurons in the PVN, while in the SON it represented 28%, 53% respectively; (3) V(1b)R-IR and OTR-IR neurons occupied all portions of the NTS and DMV. In the RWIS rats, more than 10% of OTR-IR and V(1b)R-IR neurons were activated in the DMV, while lower ratio in the NTS. RWIS activates both oxytocinergic and vasopressinergic neurons in the PVN and SON, which may project to the NTS or DMV mediating the activity of the neurons by OTR and V(1b)R.PLoS ONE 08/2011; 6(8):e23362. DOI:10.1371/journal.pone.0023362 · 3.53 Impact Factor
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ABSTRACT: This study was designed to observe the role of FOS protein expression in the rat medullary visceral zone (MVZ) in multiple organ dysfunction syndrome (MODS) caused by subarachnoid hemorrhage (SAH), with and without severing the vagus nerve. We also investigated the regulatory and control mechanisms of the MVZ and the vagus nerve in MODS following SAH. A model of MODS following SAH was established by injecting arterial blood into the Willis' circle. The vagus nerve was cut off and blocked. The FOS protein expression in the MVZ was detected by immunohistochemistry. The positive expression levels of FOS in the MVZ in the SAH and SAH + severed-down vagus nerve (SDV) groups were higher than those in the normal control, sham surgery and SDV groups (P<0.01). However, expression in the SAH+SDV group was lower than that in the SAH group (P<0.01). Inflammatory damage was observed in each visceral organ at every time-phased point in the SAH group and the SAH+SDV group. The most apparent damage was at 24-36 h, consistent with the peak of FOS protein expression; the SAH+SDV group presented a greater level of damage. The inflammatory changes in surrounding visceral organs following SAH correlated with FOS protein expression in the MVZ, which indicates that the MVZ participates in the functional control of surrounding visceral organs following SAH. Severing the subphrenic vagus nerve increases the incidence of MODS following SAH and enhances SAH-induced inflammatory damage to the surrounding visceral organs, which indicates that the vagus nerve plays a role in the protection of the surrounding visceral organs in MODS following SAH.Experimental and therapeutic medicine 01/2013; 5(1):223-228. DOI:10.3892/etm.2012.770 · 0.94 Impact Factor
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ABSTRACT: Tail pinch stimulates food intake in rats. We investigated brain mechanisms of this response and the influence of repeated exposure. Sprague-Dawley rats received acute (5 min) or repeated (5 min/day for 14 days) tail pinch using a padded clip. Acute tail pinch increased 5-min food intake compared to control (0.92 ± 0.2 vs. 0.03 ± 0.01 g, P<0.01). This response was inhibited by 76% by intracerebroventricular injection of BIBP-3226, a neuropeptide Y1, (NPY1) antagonist, increased by 48% by astressin-B, a corticotropin releasing factor (CRF) antagonist and not modified by S-406-028, a somatostatin subtype 2 antagonist. After the 5-min tail pinch without food, blood glucose rose by 21% (P<0.01) while changes in plasma acyl ghrelin (+41%) and ACTH (+37%) were not significant. Two tail pinches (45 min apart) activate pontine and hindbrain catecholaminergic and hypothalamic paraventricular CRF neurons. After 14 days repeated tail pinch, the 5-min orexigenic response was not significantly different from days 2-11 but reduced by 50% thereafter (P<0.001). Simultaneously, the 5-min fecal pellet output increased during the last 5 days compared to the first 5 days (+58%, P<0.05). At day 14, the body weight gain was reduced by 22%, with a 99% inhibition of fat gain and a 25% reduction in lean mass (P<0.05). The orexigenic response to acute 5-min tail pinch is likely to involve activation of brain NPY1 signaling while that of CRF tends to dampen the acute response and may contribute to increased defecation and decreased body weight gain induced by repeated tail pinch.AJP Regulatory Integrative and Comparative Physiology 12/2013; 306(3). DOI:10.1152/ajpregu.00335.2013 · 3.53 Impact Factor