Recovery of motor function after traumatic spinal cord injury by using plasma-synthesized polypyrrole/iodine application in combination with a mixed rehabilitation scheme.

Traumatic spinal cord injury (TSCI) can cause paralysis and permanent disability. Rehabilitation (RB) is currently the only accepted treatment, although its beneficial effect is limited. The development of biomaterials has provided therapeutic possibilities for TSCI, where our research group previously showed that the plasma-synthesized polypyrrole/iodine (PPy/I), a biopolymer with different physicochemical characteristics than those of the PPy synthesized by conventional methods, promotes recovery of motor function after TSCI. The present study evaluated if the plasma-synthesized PPy/I applied in combination with RB could increase its beneficial effects and the mechanisms involved. Adult rats with TSCI were divided into no treatment (control); biopolymer (PPy/I); mixed RB by swimming and enriched environment (SW/EE); and combined treatment (PPy/I + SW/EE) groups. Eight weeks after TSCI, the general health of the animals that received any of the treatments was better than the control animals. Functional recovery evaluated by two scales was better and was achieved in less time with the PPy/I + SW/EE combination. All treatments significantly increased ßIII-tubulin (nerve plasticity) expression, but only PPy/I increased GAP-43 (nerve regeneration) and MBP (myelination) expression when were analyzed by immunohistochemistry. The expression of GFAP (glial scar) decreased in treated groups when determined by histochemistry, while morphometric analysis showed that tissue was better preserved when PPy/I and PPy/I + SW/EE were administered. The application of PPy/I + SW/EE, promotes the preservation of nervous tissue, and the expression of molecules related to plasticity as ßIII-tubulin, reduces the glial scar, improves general health and allows the recovery of motor function after TSCI. The implant of the biomaterial polypyrrole/iodine (PPy/I) synthesized by plasma (an unconventional synthesis method), in combination with a mixed rehabilitation scheme with swimming and enriched environment applied after a traumatic spinal cord injury, promotes expression of GAP-43 and ßIII-tubulin (molecules related to plasticity and nerve regeneration) and reduces the expression of GFAP (molecule related to the formation of the glial scar). Both effects together allow the formation of nerve fibers, the reconnection of the spinal cord in the area of injury and the recovery of lost motor function. The figure shows the colocalization (yellow) of ßIII-tubilin (red) and GAP-43 (green) in fibers crossing the epicenter of the injury (arrowheads) that reconnect the rostral and caudal ends of the injured spinal cord and allowed recovery of motor function.

Comparative effects of injecting 5,6-dihydroxytryptamine in the dorsal or medial raphe nuclei on rat puberty.

The role played by the serotoninergic system in the control of puberty onset and first ovulation in rats is studied in this paper by analyzing the effects of injecting the neurotoxin 5,6-dihydroxytryptamine (5,6-DHT) into the dorsal (DRN) or medial (MRN) raphe nucleus of 30-day-old female rats. Complete lesion to the DRN resulted in the blockade of ovulation and a decrease in both the number of ovarian follicles and the serum concentration of follicle stimulating hormone (FSH). This treatment was also found to be associated with an increase in serotoninergic activity in the anterior and medial hypothalami. A lesion to the central portion of the DRN resulted in a significant decrease in the concentration of progesterone in serum and in the number of ova shed by ovulating animals. The lesion to the lateral portion of the DRN did not have an apparent effect on ovulation rate, the number of ova shed, nor in hormone serum concentration. The injection of propranolol to rats with a lesion to the DRN restored ovulation in 73% of treated animals and returned serotoninergic activity in the anterior hypothalamus to levels similar to those of sham-operated animals. In turn, in the medial hypothalamus, the increase in serotoninergic activity was not modified. The results presented herein suggest that serotoninergic inputs to the anterior hypothalamus have a direct influence on gonadotropin secretion and first ovulation, while the noradrenergic innervation exerts an indirect influence.