When applied in vitro to various CNS structures 5-HT and/or NMDA have been observed to generate rhythmic nervous activity. In contrast, reports of similar in vivo actions are relatively rare. Here we describe a physiological sympathetic motor rhythm regulating the thermoregulatory circulation of the rat tail (T-rhythm; 0.40-1.20 Hz) that can be elicited following intrathecal (I.T.) application of 5-HT to an in situ 'isolated' spinal cord preparation (anaesthetized rats spinalized at T10-T11 and cauda equina cut). I.T. injections were delivered to L1 as sympathetic neuronal activity to the tail (SNAT) arises from preganglionic neurones at T11-L2. SNAT was abolished after spinal transection (n = 18) and it did not return spontaneously. The administration of 5-HT (250 nmol) generated rhythmic sympathetic discharges (n = 6). The mean frequency of the T-like rhythm during the highest level of activity was 0.88 ± 0.04 Hz which was not significantly different from the T-rhythm frequency observed in intact animals (0.77 ± 0.02 Hz; P > 0.05 n = 16). In contrast, NMDA (1 μmol) generated an irregular tonic activity, but it failed to generate a T-like rhythm (n = 9), even though the mean levels of activity were not significantly different to those produced by 5-HT. However, 5-HT (250 nmol) applied after NMDA generated a T-like rhythm (0.95 ± 0.11 Hz, n = 6). Our observations support the idea that 5-HT released from rostral ventromedial medullary neurones, known to innervate sympathetic preganglionic neurones, can induce sympathetic rhythmic activity.
Patients are increasingly seeking uterus-preserving, minimally invasive treatments for symptomatic uterine fibroids. This has led to a greater use of nonresective treatments such as uterine artery embolization (UAE), focused ultrasound (FUS) and more recently, radiofrequency ablation (RFA) of fibroids. This systematic review, following PRISMA guidelines, examines the change in uterine and fibroid volumes associated with UAE, FUS, and RFA. Pubmed and MedlinePlus databases were searched from 1956 to 2016. The keywords used were 'radiofrequency ablation,' 'magnetic resonance guided focused ultrasound,' 'ultrasound guided focused ultrasound', 'uterine artery embolization,' 'uterine fibroid embolization,' and 'leiomyoma' or 'fibroid'. Publications with at least 20 patients were included. Data were collected and analyzed using Microsoft Excel V R (Microsoft Corporation, Redmond, WA) software. Eighty-one relevant papers were identified: 52 related to UAE, 11 to RFA, 17 to FUS, 1 compared UAE and FUS. We report the published uterine volume and fibroid volume changes seen in these studies at 1 to 36 months. The pooled fibroid volume reductions at six months seen with RFA were 70%, UAE 54% and FUS 32%. All three types of nonresective treatment result in fibroid volume reduction. However, fibroid volume reduction is most marked with RFA, with UAE resulting in the next most volume reduction. Additional larger cohort studies, including those that are randomized and/or comparative, would enable definitive conclusions. This is the first systematic review comparing uterine and fibroid volume reduction after RFA, UAE and MRgFUS.
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