Several pairs of AKR strain mice were donated to our laboratory by the Jackson Laboratory(Bar Har... more Several pairs of AKR strain mice were donated to our laboratory by the Jackson Laboratory(Bar Harbor) in 1968. We continued the sister-brother mating of these mice and became aware of some litters which showed a moderate to severe loss of action, hair loss, skin coarseness, and a shortened life span. We selected and maintained 6 substrains with severe exhaustion as accelerated senescence prone(SAM-P/l,-P/2,-P/3,-P/4,-P/6,-P/8) and 3 substrains with normal aging process as accelerated senescence resistant(SAM-R/1,-R/2, -R/3).1 Judging from findings in the survivors and for Gompertzian function of the growth pattern, the aging pattern in this SAM model seems to relate to an accelerated senescence rather than to premature aging. Recently, SAM-P/8 was reported to show age-related learning and memory deficits in passive avoidance performance under specific pathogen-free conditions.2 In this present study, we examined age-related changes in memory of SAM-P/8 under conventional conditions and found that SAM-P/8 is a pertinent model for researching disturbances of recent memory with aging in animals and humans.
Publisher Summary The establishment of stroke-prone spontaneously hypertensive rats (SHRSP), of w... more Publisher Summary The establishment of stroke-prone spontaneously hypertensive rats (SHRSP), of which more than 80% died of stroke, has led to extensive study on the mechanisms of cerebrovascular lesions. Studies have revealed that hypertension is the most important systemic factor for stroke. Other possible factors are the alteration of the physical characteristics of the arterial wall, and involvement of humoral factors such as renin. Further, the angioarchitectural studies have clarified that the predilection sites of stroke are the boundary zone of the three main cerebral arterial supplies and the areas fed by recurrent arteries. This chapter presents the assay of norepinephrine in the brain quantitatively or by fluorescent histochemical methods. regional cerebral blood flow (rCBF) tends to increase under hypertensive state below 200 mm Hg but decreases abruptly in SHRSP with severe hypertension over 220 mm Hg.
Age-related changes in the brain transfer of blood-borne horseradish peroxidase (HRP) were examin... more Age-related changes in the brain transfer of blood-borne horseradish peroxidase (HRP) were examined by light microscopy in senescence-accelerated prone mice (SAMP8) and senescence-accelerated resistant mice (SAMR1). The intracerebral HRP transferred from the blood stream was reacted with tetramethyl benzidine (TMB) and the area showing the presence of HRP-TMB reaction products was morphometrically evaluated. Areas containing HRP reaction products in the medial CA1 region and medial dentate gyrus of the hippocampus were observed in 3- and 13-month-old SAMP8 and SAMR1. The mean percentage of the positive area for the HRP to the area of interest was significantly higher in the rostral portion of the hippocampus in 13-month-old than in 3-month-old SAMP8. On the other hand, age-related changes in the area positive for HRP-TMB reaction products in the cortices and the caudal portion of the hippocampus in SAMP8 were not observed. In addition, positive staining reaction for HRP was also observed in the dorsal portion of the thalamus of 13-month-old SAMP8. There were no significant age-related changes in the area positive for HRP-TMB reaction products in rostral and caudal portions of the cortices and the hippocampus of SAMR1. These findings suggest that blood-borne macromolecules have access to the medial and rostral portion of the hippocampus, that this phenomenon becomes more pronounced during the process of senescence in the SAMP8 brain and, moreover, that intravascular macromolecules have access to the dorsal portion (periventricular area) of the thalamus of 13-month-old SAMP8.
The passage of blood-borne horseradish peroxidase (HRP) into the amygdaloid area of the mouse bra... more The passage of blood-borne horseradish peroxidase (HRP) into the amygdaloid area of the mouse brain was examined with light and electron microscopy. Staining reaction for HRP appeared in medial portions of the amygdaloid area, especially adjacent to the optic tract. Ultrastructural examination of some vessels in that area revealed that the staining reaction for HRP appeared in the perivascular space, the basal lamina, the cytoplasm or vesicular structures of the perivascular cells, vesicular profiles of the endothelial cell cytoplasm including abluminal pits and the adjacent extracellular space. These findings suggest that intravascular macromolecules can invade medial portions of the amygdaloid area of the mouse brain.
Several pairs of AKR strain mice were donated to our laboratory by the Jackson Laboratory(Bar Har... more Several pairs of AKR strain mice were donated to our laboratory by the Jackson Laboratory(Bar Harbor) in 1968. We continued the sister-brother mating of these mice and became aware of some litters which showed a moderate to severe loss of action, hair loss, skin coarseness, and a shortened life span. We selected and maintained 6 substrains with severe exhaustion as accelerated senescence prone(SAM-P/l,-P/2,-P/3,-P/4,-P/6,-P/8) and 3 substrains with normal aging process as accelerated senescence resistant(SAM-R/1,-R/2, -R/3).1 Judging from findings in the survivors and for Gompertzian function of the growth pattern, the aging pattern in this SAM model seems to relate to an accelerated senescence rather than to premature aging. Recently, SAM-P/8 was reported to show age-related learning and memory deficits in passive avoidance performance under specific pathogen-free conditions.2 In this present study, we examined age-related changes in memory of SAM-P/8 under conventional conditions and found that SAM-P/8 is a pertinent model for researching disturbances of recent memory with aging in animals and humans.
Publisher Summary The establishment of stroke-prone spontaneously hypertensive rats (SHRSP), of w... more Publisher Summary The establishment of stroke-prone spontaneously hypertensive rats (SHRSP), of which more than 80% died of stroke, has led to extensive study on the mechanisms of cerebrovascular lesions. Studies have revealed that hypertension is the most important systemic factor for stroke. Other possible factors are the alteration of the physical characteristics of the arterial wall, and involvement of humoral factors such as renin. Further, the angioarchitectural studies have clarified that the predilection sites of stroke are the boundary zone of the three main cerebral arterial supplies and the areas fed by recurrent arteries. This chapter presents the assay of norepinephrine in the brain quantitatively or by fluorescent histochemical methods. regional cerebral blood flow (rCBF) tends to increase under hypertensive state below 200 mm Hg but decreases abruptly in SHRSP with severe hypertension over 220 mm Hg.
Age-related changes in the brain transfer of blood-borne horseradish peroxidase (HRP) were examin... more Age-related changes in the brain transfer of blood-borne horseradish peroxidase (HRP) were examined by light microscopy in senescence-accelerated prone mice (SAMP8) and senescence-accelerated resistant mice (SAMR1). The intracerebral HRP transferred from the blood stream was reacted with tetramethyl benzidine (TMB) and the area showing the presence of HRP-TMB reaction products was morphometrically evaluated. Areas containing HRP reaction products in the medial CA1 region and medial dentate gyrus of the hippocampus were observed in 3- and 13-month-old SAMP8 and SAMR1. The mean percentage of the positive area for the HRP to the area of interest was significantly higher in the rostral portion of the hippocampus in 13-month-old than in 3-month-old SAMP8. On the other hand, age-related changes in the area positive for HRP-TMB reaction products in the cortices and the caudal portion of the hippocampus in SAMP8 were not observed. In addition, positive staining reaction for HRP was also observed in the dorsal portion of the thalamus of 13-month-old SAMP8. There were no significant age-related changes in the area positive for HRP-TMB reaction products in rostral and caudal portions of the cortices and the hippocampus of SAMR1. These findings suggest that blood-borne macromolecules have access to the medial and rostral portion of the hippocampus, that this phenomenon becomes more pronounced during the process of senescence in the SAMP8 brain and, moreover, that intravascular macromolecules have access to the dorsal portion (periventricular area) of the thalamus of 13-month-old SAMP8.
The passage of blood-borne horseradish peroxidase (HRP) into the amygdaloid area of the mouse bra... more The passage of blood-borne horseradish peroxidase (HRP) into the amygdaloid area of the mouse brain was examined with light and electron microscopy. Staining reaction for HRP appeared in medial portions of the amygdaloid area, especially adjacent to the optic tract. Ultrastructural examination of some vessels in that area revealed that the staining reaction for HRP appeared in the perivascular space, the basal lamina, the cytoplasm or vesicular structures of the perivascular cells, vesicular profiles of the endothelial cell cytoplasm including abluminal pits and the adjacent extracellular space. These findings suggest that intravascular macromolecules can invade medial portions of the amygdaloid area of the mouse brain.
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Papers by Ichiro Akiguchi