Renal nerve ultrastructural alterations in short term and long term experimental diabetes.

BACKGROUND: Despite the evidence that renal hemodynamics is impaired in experimental diabetes, associated with glomeruli structural alterations, renal nerves were not yet investigated in experimental models of diabetes and the contribution of nerve alterations to the diabetic nephropathy remains to be investigated. We aimed to determine if ultrastructural morphometric parameters of the renal nerves are affected by short term and/or long term experimental diabetes and if insulin treatment reverses these alterations. Left renal nerves were evaluated 15 days or 12 weeks (N = 10 in each group) after induction of diabetes, with a single injection of streptozotocin (STZ). Control rats (N = 10 in each group) were injected with vehicle (citrate buffer). Treated animals (N = 10 in each group) received a single subcutaneous injection of insulin on a daily basis. Arterial pressure, together with the renal nerves activity, was recorded 15 days (short-term) or 12 weeks (long-term) after STZ injection. After the recordings, the renal nerves were dissected, prepared for light and transmission electron microscopy, and fascicle and fibers morphometry were carried out with computer software. RESULTS: The major diabetic alteration on the renal nerves was a small myelinated fibers loss since their number was smaller on chronic diabetic animals, the average morphometric parameters of the myelinated fibers were larger on chronic diabetic animals and distribution histograms of fiber diameter was significantly shifted to the right on chronic diabetic animals. These alterations began early, after 15 days of diabetes induction, associated with a severe mitochondrial damage, and were not prevented by conventional insulin treatment. CONCLUSIONS: The experimental diabetes, induced by a single intravenous injection of STZ, in adult male Wistar rats, caused small fiber loss in the renal nerves, probably due to the early mitochondrial damage. Conventional treatment with insulin was able to correct the weight gain and metabolic changes in diabetic animals, without, however, correcting and / or preventing damage to the thin fibers caused by STZ-induced diabetes. The kidney innervation is impaired in this diabetic model suggesting that alterations of the renal nerves may play a role in the development of the diabetic nephropathy.

Transcutaneous electrical nerve stimulation, acupuncture, and spinal cord stimulation on neuropathic, inflammatory and, non-inflammatory pain in rat models.

BACKGROUND: Transcutaneous electrical nerve stimulation (TENS), manual acupuncture (MA), and spinal cord stimulation (SCS) are used to treat a variety of pain conditions. These non-pharmacological treatments are often thought to work through similar mechanisms, and thus should have similar effects for different types of pain. However, it is unclear if each of these treatments work equally well on each type of pain condition. The purpose of this study was to compared the effects of TENS, MA, and SCS on neuropathic, inflammatory, and non-inflammatory pain models. METHODS: TENS 60 Hz, 200 µs, 90% motor threshold (MT), SCS was applied at 60 Hz, an intensity of 90% MT, and a 0.25 ms pulse width. MA was performed by inserting a stainless-steel needle to a depth of about 4-5 mm at the Sanyinjiao (SP6) and Zusanli (ST36) acupoints on a spared nerve injury (SNI), knee joint inflammation (3% carrageenan), and non-inflammatory muscle pain (intramuscular pH 4.0 injections) in rats. Mechanical withdrawal thresholds of the paw, muscle, and/or joint were assessed before and after induction of the pain model, and daily before and after treatment. RESULTS: The reduced withdrawal thresholds were significantly reversed by application of either TENS or SCS (P < 0.05). MA, on the other hand, increased the withdrawal threshold in animals with SNI and joint inflammation, but not chronic muscle pain. CONCLUSIONS: TENS and SCS produce similar effects in neuropathic, inflammatory and non-inflammatory muscle pain models while MA is only effective in inflammatory and neuropathic pain models.

Morphometry of saphenous nerve in young rats.

The rat saphenous nerve contains only somato-sensory fibers and is used in investigations of neuropathic pain and its treatment. Due to its superficial anatomical path, the saphenous nerve is also widely used in electrophysiological studies. Nevertheless, morphologic and morphometric descriptions of the normal saphenous nerve are scanty in the literature and information on useful morphometric parameters of this nerve is still missing. Thus, the present study aimed to investigate the longitudinal and lateral symmetry of the saphenous nerve in young rats. Proximal and distal segments of the left and right saphenous nerves from female Wistar rats, aged 30 days (N=5) were morphometrically evaluated and comparisons were made between sides and segments. Our results show that the saphenous nerve is longitudinally and laterally symmetric since there were no morphometric differences between proximal and distal segments, as well as between right and left sides. This lateral symmetry is important in order to validate those experiments in which the contralateral nerve is used as the control. Also, the longitudinal symmetry information is fundamental to further studies involving the "dying back" neuropathy models. The present study adds to the literature new morphometric information on the rat saphenous nerve that might be useful for a better interpretation of further studies involving this nerve and experimental models of nerve diseases.

Ultrastructural anatomy of the renal nerves in rats.

The innervation within mammalian kidneys (intrinsic innervation) has been extensively described in the literature, particularly for rats. In contrast, there is still a lack of detailed description of the morphology of the extrinsic renal nerves leading to the kidney. The aim of the present study was to describe, in detail, the morphology of the renal nerves in rats. Left renal nerves were evaluated in 6 normal adult Wistar rats. After nerve recordings, in order to ascertain that the nerves studied were the extrinsic renal nerves, rats were killed and the nerves prepared for transmission electron microscopy. Morphometry was carried out with the aid of computer software. The total numbers of myelinated and unmyelinated fibers were 22+/-6 and 1246+/-110, respectively, with a ratio of unmyelinated/myelinated fiber of 109+/-26. The diameters of myelinated fibers showed an unimodal distribution with a peak at 3.0 microm but more than 17% of the fibers showed diameters larger than 5 microm. Unmyelinated fiber distribution was unimodal, with peak between 0.5 and 0.7 microm. The present study adds new information on the morphology of renal nerves in rats and provides morphological basis for further studies involving the structural basis of altered renal responses in conditions such as hypertension, ageing, diabetes and peripheral neuropathies.

Neuroimaging and motor development of twins with congenital microcephaly associated with Zika virus: a case report / Neuroimagem e desenvolvimento motor de gêmeas com microcefalia congênita por Zika virus: estudo de caso

Objective: We aimed to describe a case of congenital microcephaly caused by Zika virus infection in a monozygotic twin pregnancy. Methods: Transfontanelle ultrasonography and cranial computed tomography revealed different lesion patterns for both twins with congenital microcephaly caused by Zika virus infection. Motor development assessments were performed using the Alberta Infant Motor Scale and the Gross and Motor Function Measure before, during, and after physiotherapy. Results: The evaluations showed differences in motor acquisition between the twins. The values in the first case were much lower than those in the second case, which showed more motor delay. Conclussion: The present study showed that despite the twins being monozygotic, the effects of neurological lesions as revealed by neuroimaging were worse in the first case, and even with two weekly rehabilitation sessions, motor development over time was considerably worse in the twin in case 1 than in the other twin.

Objetivo: Descrever um caso de microcefalia congênita causada pela infecção do Zika vírus em uma gestação gemelar monozigótica. Métodos: A ultrassonografia transfontanelar e a tomografia computadorizada de crânio revelaram diferentes padrões de lesão para ambos gêmeos com microcefalia congênita causada pela infecção do Zika vírus. As avaliações do desenvolvimento motor foram realizadas por meio da Escala Motora Infantil de Alberta (EMIA) e da Medida de Função Motora Grossa antes, durante e após o tratamento fisioterapêutico. Resultados: As avaliações mostraram diferenças na aquisição motora entre os gêmeos. Os valores nas avaliações do primeiro caso foram bem menores do que os do segundo caso, que apresentou maior atraso motor. Conclusão: O presente estudo mostrou que apesar dos gêmeos serem monozigóticos, os efeitos das lesões neurológicas reveladas por exames de neuroimagem foram piores no primeiro caso, e mesmo com duas sessões semanais de reabilitação, o desenvolvimento motor ao longo do tempo foi consideravelmente pior no gêmeo do caso 1 quando comparado ao caso 2.

Association of chronic diabetes and hypertension in sural nerve morphometry: an experimental study.

BACKGROUND: Prospective studies have shown incidence rates of hypertension in diabetes mellitus to be three times that of subjects without diabetes mellitus. The reverse also applies, with the incidence of diabetes two to three times higher in patients with hypertension. Despite this common clinical association, the contribution of each isolated entity in the development of a neuropathy is still not well understood. The aims of the present study were to investigate the presence of peripheral neuropathy in spontaneously hypertensive rats (SHR) and SHR with chronically induced diabetes, using a morphological and morphometric study of the sural nerves. METHODS: Female SHR and normotensive Wistar rats (WR), 8 weeks old, received a single intravenous injection of streptozotocin (STZ) through the tail vein. Controls from both strains received vehicle. Twelve weeks after the injection, sural nerves were dissected and prepared for light microscopy. Morphometry of sural nerve fascicles and myelinated fibers was performed with the aid of computer software. RESULTS: The sural nerve myelinated fibers were highly affected by experimental diabetes in normotensive rats, causing mainly the reduction of the fiber size. Hypertensive rats showed characteristics of small fiber neuropathy and a severe reduction of the number and density or Schwann cells. The association between diabetes and hypertension caused an increase on the average size of the myelinated fibers, pointing to a small fiber loss, associated to axonal atrophy. CONCLUSIONS: Our study gives morphological support to the existence of a neuropathy due to hypertension, which is among one of the most common risk factors for diabetic neuropathy. The association between the two neuropathies showed to be a complex alteration, involving and including both, large and small fibers neuropathy. Hypertension caused, indeed, an exacerbation of the alterations already observed in experimental models of diabetic neuropathy.

Cortex glial cells activation, associated with lowered mechanical thresholds and motor dysfunction, persists into adulthood after neonatal pain.

We investigated if changes in glial activity in cortical areas that process nociceptive stimuli persisted in adult rats after neonatal injury. Neonatal pain was induced by repetitive needle prickling on the right paw, twice per day for 15 days starting at birth. Wistar rats received either neonatal pain or tactile stimulation and were tested behaviorally for mechanical withdrawal thresholds of the paws and gait alterations, after 15 (P15) or 180 (P180) days of life. Brains from rats on P15 and P180 were immunostained for glial markers (GFAP, MCP-1, OX-42) and the following cortical areas were analyzed for immunoreactivity density: prefrontal, anterior insular, anterior cingulated, somatosensory and motor cortices. Withdrawal thresholds of the stimulated paw remained decreased on P180 after neonatal pain when compared to controls. Neonatal pain animals showed increased density for both GFAP and MCP-1 staining, but not for OX-42, in all investigated cortical areas on both experimental times (P15 and P180). Painful stimuli in the neonatal period produced pain behaviors immediately after injury that persisted in adult life, and was accompanied by increase in the glial markers density in cortical areas that process and interpret pain. Thus, long-lasting changes in cortical glial activity could be, at least in part, responsible for the persistent hyperalgesia in adult rats that suffered from neonatal pain.