Effect of whisker trimming on behavior and barrel cortex of rat / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the change of behavior, as well as the plasticity of somatosensory cortex after whisker trimming.</p><p><b>METHODS</b>SD rats were divided into 4 groups. Group A is the normal control group; group B: bilateral vibrissotomy on the second postnatal day; group C: unilateral right vibrissotomy on the second postnatal day; group D: right unilateral whisker trimmed during 1-5 days after birth, and leave untreated after the 5th postnatal day. Their body weight, length of the left D2 whiskers was measured on the 30th postnatal day. At the same time, the changes of their behavior (including the slit-detection test, the home exploring behavior and thigmotaxis test) were also recorded on the 30th postnatal day. Cytochrome oxydase histochemistry (CO reaction)was applied to study the development and arrangement of barrel cortex.</p><p><b>RESULTS</b>In the slit-detection test, control rats could find and get into the right slit very quickly. The rats in group B could get into the slit only if their noses touched the slit. The rats in group C couldn't identify the slit by right face, but if they turned their body and touched the slit with the left whiskers, they could get into the slit very quickly. The behavior of rats in group D was similar to that in group C. The time spent for finding out the right slit of the rats in group A, B, C was obviously longer than that of group A (P < 0.01, P < 0.05, P < 0.01). In the exploring behavior and thigmotaxis test, the time for left thigmotaxis, right thigmotaxis and total thigmotaxis of rats in group B was longer than that of control animals. The time for right thigmotaxis of group C was significantly shorter than that of group A (P < 0.05). Both the weight of the rats and the length of left D2 whiskers of rats in all the four groups had no significant difference. CO reaction showed that the barrels became smaller, the septum was not clear, the arrangement of the barrels was not tidy in the mice whose right whiskers were trimmed from 2-30 days after birth.</p><p><b>CONCLUSION</b>Deafferentation doesn't change the body weight and length of the whiskers left. But the stimulation of whiskers is important for rodent especially in thigmotaxis and exploring behavior. Deafferentation can also induce the plastic change of barrel cortex.</p>

The protective effect of melatonin on auditory cortex toxicity induced by cis-platinum / 中国应用生理学杂志

<p><b>AIM</b>To investigate the toxic response in auditory cortex of guinea pigs caused by cis-platinum (DDP), and the protective role of melatonin in this effect.</p><p><b>METHODS</b>Cis-platinum and melatonin were injected peritoneally. LDH, MDA, NO in the auditory cortex were detected by spectrophotometeR.</p><p><b>RESULTS</b>The body weight of the guinea pigs was diminished by peritoneal injection of Cis-platinum for 7 days (P < 0.01). Peritoneal injection of Cis-platinum induced the increased leakage of LDH (P < 0.05 vs injection of normal saline). This effect was reduced by injection of MT (P < 0.05). The content of MDA in the auditory cortex was also increased because of injection of Cis-platinumv for 7 days (P < 0.01) and MT reduced this effect (P < 0.05). The change of NO in the auditory cortex was not statistically significant after injection of Cis-platinum or Cis-platinum with MT.</p><p><b>CONCLUSION</b>Peritoneal injection of Cis-platinum could destroy neurons in the auditory cortex. This effect could be reduced by melatonin by an anti-free radials mechanism.</p>

Endothelium-independent vasorelaxation of plant-derived estrogen biochanin A and its mechanism in rat aortic rings / 中国应用生理学杂志

<p><b>AIM</b>To investigate the mechanisms of vasodilatation of plant-derived estrogen biochanin A.</p><p><b>METHODS</b>Isolated aortic ring preparations from Sprague-Dawley rats were suspended in individual organ baths. The tension was measured isometrically.</p><p><b>RESULTS</b>Biochanin A at the range of 10(-9)-10(-4) mol/L provoked concentration-dependent and endothelium-independent relaxation of the rings constricted by phenylephrine (10(-5) mol/L). Biochanin A caused concentration-dependent relaxation of denuded rings precontracted with KCl (6 x 10(-2) mol/L). Glibenclamide (3 x 10(-6) mol/L), a selective inhibitor of ATP-sensitive potassium channels, and tetraethylammonium (5 x 10(-3) mol/L), a Ca2+ -activated K+ channel inhibitor, significantly attenuated the relaxation induced by biochanin A. The vasoconstriction induced by phenylephrine was decreased by biochanin A in Ca2+ -free medium.</p><p><b>CONCLUSION</b>The endothelium-independent relaxation of thoracic aorta induced by biochanin A might be mediated by ATP-sensitive K+ channels, Ca2+ -activated K+ channels and intracellular Ca2+ release from sarcoplasmic reticulum.</p>

Mechanisms of the effect of brain histamine on chronic epilepsy induced by pentylenetetrazole / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the mechanisms of histamine on chronic epilepsy induced by pentylenetetrazole (PTZ).</p><p><b>METHODS</b>To induce chemical kindling, a subconvulsive dose (35mg/kg) of PTZ was ip injected every 48 h in rats. Behavior changes were observed for 30 min after every injection of PTZ.</p><p><b>RESULT</b>Ip injection of histidine or icv injection of clobenpropit inhibited the development of kindling induced by PTZ, presenting prolonged latency for myoclonic jerks and clonic generalized seizures and depressed seizure stages in a dose-dependent manner. H(3)receptor agonist, immepip, and histidine decarboxylase, alpha-fluoromethylhistidine reversed the ameliorating effect of clobenpropit on seizure development in a dose-dependent manner.</p><p><b>CONCLUSION</b>Brain histamine plays an important role in protection against myoclonic jerks and clonic generalized clonic seizures and its action may be via H(3)receptor.</p>