A study of regional cerebral blood flow (rCBF), distribution of benzodiazepine receptor and nueronal density and alteration after transient forebrain ischemia in the mongolian gerbil *
The response of many intracerebral receptors to ischemic insult is not known. In particular, there have been few reports comparing regional cerebral blood flow (ｒＣＢＦ) and the distribution of inhibitive benzodiazepine receptor (ＢＺＲ) and neuronal density in the whole brain. Furthermore, there have only a few chronological experiments comparing ｒＣＢＦ following transient forebrain ischemia (five minutes) with the distribution of ＢＺＲ. In the present experiment, we determined ｒＣＢＦ and the distributions of ＢＺＲ and neurons employing the procedures of nuclear medicine and histology in normal mongolian gerbils. The binding of radioligands,Ｎ-isopropyl-p- 〔123 Ⅰ〕iodoamphetamine (123Ⅰ -IMP) and 125Ⅰ -iomazenil (125Ⅰ -ＩＭＺ), was determined autoradiographically to the brain to estimate the ｒＣＢＦ and ＢＺＲ in each region. The density of neurons was determined by counting the number of neurons stained by hematoxylin - eosin (ＨＥ stain) in the corresponding regions to that examined by autoradiography (ＡＲＧ). Then a model of transient forebrain ischemia was prepared to compare the ＣＡ１ region of the hippocampus, with a region which was demonstrated no change in neurons. In the ＣＡ１ region of the hippocampus, delayed neuronal death was occurred after five minutes of transient forebrain ischemia. It was observed that ｒＣＢＦ was high in regions where the density of neurons tended to be high except thalamus and dentate gyrus of the hippocampus. There was no confirmed relationship between the rates of accumulation of the ＢＺＲ and the densities of neurons. It was suggested that the ＢＺＲ distribution might be different in each neuron . After the ischemic treatment, the ｒＣＢＦ level was transiently elevated in the ＣＡ１ region of the hippocampus. No obvious reduction of ＢＺＲ was observed in the ＣＡ１ region in spite of some neurons died. It was proved that the distribution of ＢＺＲ in the acute phase after the ischemic insult do not always reflect the survival rate of neurons. (Accepted on October 31, 1997) Kawasaki Igakkaishi 23(3) : 175-184, 1997
