ABSTRACT
Objective To detect the percentage of cultured neuron apoptosis after the neurons were treated with anoxia and specific inhibitors of protein kinase A (PKA) and protein kinase C (PKC). Methods After establishment of the model of neurons cultured under hypoxic condition, the neurons were cocultured with different concentrations of Rp-cAMP and Calphostin C, specific inhibitors of protein kinase A and C, respectively. Then neurons were cultured under an ischemic condition until the number of survived neurons, the activity of mPKA,and mPKC, and the apoptotic neurons stained by TUNEL in each group were observed. Results The activity of mPKA and mPKC significantly increased after the onset of hypoxia. With the increases in concentrations of Rp-cAMP or Calphostin C, the percentage of apoptotic neurons obviously decreased or increased, respectively. Conclusion The pathways of PKA and PKC signal transduction may participate in the hypoxic neuron injury. The functions of these two kinases are opposite for apoptotic regulation. It suggests that the signal transduction of PKA and PKC in hypoxic neurons belongs to a monophasic controlling system and the ratio of PKA to PKC in cells may determine the survival of hypoxic neurons.
ABSTRACT
Objective To establish a cerebral hemorrhage model in rats by local injection of type Ⅳcollagenase, and explore the factors affecting the speed and volume of hematoma formation Methods A total of 150 healthy male Wistar rats weighing from 200 to 250 g were randomly divided into 3 groups, control, collagenase, and collagenase/heparin groups Animals in those groups received injection of saline, collagenase (0 2 U/?l), and collagenase (same dose) and heparin (2 U/?l) with different volume respectively at the caudate nucleus The volume of the hematoma in the rats ( n =6 at each time point) was observed 6, 12, and 24 h, and 3, 7d after the injection Results Permeation of blood was found in 12 h after injection in control group Hematoma about 3 mm in diameter was found in 3 d after injection in collagenase group, while in collagenase/heparin group, it was found in 24 h Conclusion Cerebral hemorrhage model established by local injection of collagenase/heparin in saline solution is ideal and reliable, and the size of hematoma is in correlation with the volume of solutions injected into the brain
ABSTRACT
Objective To explore the effect and possible mechanism of protein kinase C (PKC) on the apoptosis of cultured neurons after hypoxia Methods Model of cultured rat neurons under hypoxia condition was established. Calphostin C, an inhibitor for the catalytic subunit of PKC, at 4 different concentrations were separately cocultured for 2 h with the neurons having been cultivated under hypoxic condition for different times The activity of membrane PKC (mPKC), the expression of Bcl 2 and the situation of neuron apoptosis were studied Results With the prolonging of hypoxic time the activity of mPKC was increased significantly And the expression of Bcl 2 was decreased obviously and positive rate of TUNEL were significantly increased in a calphostin C concentration dependent manner Conclusion ① The activation of mPKC and Bcl 2 are involved in the apoptosis of neurons after hypoxia ② Hypoxia and calphostin C can aggravate the hypoxic neuronal apoptosis through the signal transduction of Bcl 2 ③ The activation of PKC can protect neuron against hypoxia
ABSTRACT
Objective To investigate the relationship between the protein kinase A (PKA) and apoptosis of cultured neurons after hypoxia Methods Model of cultured rat neuron under hypoxia condition was established. Rp cAMP, a specific inhibitor for PKC, at 4 different concentrations were separately cocultured for 2 h with the neurons having been cultivated under hypoxic condition for different times The activity of PKA, the expression of caspase 3 and the situation of neuron apoptosis were studied Results With the prolonging of hypoxic time the activity of PKA was increased significantly And the expression of activated caspase 3 and apoptotic DNA were increased as well The positive rate of fluorescence staining and the average fluorescent intensity of caspase 3 and TUNEL were significantly decreased along with the increasing concentration of Rp cAMP Conclusion ① PKA and caspase 3 are involved in the neuronal apoptosis after hypoxia ② Rp cAMP can attenuate the hypoxic neuronal apoptosis through the signal transduction of caspase 3 ③ The activating of PKA can aggravate hypoxic neuron apoptosis