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Brain Research Bulkfin, Vol. 27, PP. 685-688. 0 Pergamon Press plc, 1991. Printed in the U.S.A
RAPID COMMUNICATION
Age- and Sex-Related Differences in the Nerve Growth Factor Distribution in the Rat Brain MASAKO NISHIZUKA,*’ RITSUKO KATOH-SEMBA,? KOU ETO,I. YASUMASA ARAI,* REIJI IIZUKA$ AND KANEFUSA KATO$ Lkpartments
of *Anatomy and $Psychiatry, Jiantendo ~niversi~ School @Medicine, Hongo, Tokyo 113 Japan and Depar~e~ts of ~Peri~tology and §E~o~hern~s~, institute for Developmental Research Aichi Prefecture Colony, Kasugai, Aichi 480-03 Japan
Received 24 June 1991 K. ETO, Y. ARAI, R. IIZUKA AND K. KATO. Age- and sex-r&fed ~i~fe~e~ in of the nerve growth factor (NGF) have been measured in various brain regions of young and aged male and female rats of Wistar strain by means of a highly sensitive two-site enzyme immunoassay system for P-NGF. Among the ten regions examined, the amount of NGF per wet weight of tissue was found to be highest in the hippocampus, irrespective of the sex and age. The NGF concentration in the hippocampus of female rats at 3 months of age was comparable to that of same age males. Further, there was no significant difference in the NGF leveis of the hippocampus between young and aged males. However, the NGF level was significantly lower in aged females as compared to that in 3- or 4-Mona-old females, and hence the marked male-female difference was found in the NGF levels in aged Wistar rats. NISHIZLKA, M., R. ATOM-SE~A, &e nerve grmvrh&for
~~~f~jbuf~~~ in the rat bruin. BRAIN RES BULL 27(S) 685-688, 1991. -Levels
Nerve growth factor
Aging
Sex difference
Enzyme immunoassay
THE nerve growth factor (NW) is important to the development (1, 4, 26) and aging (3, 4, 6, 8, 13, 16, 17) of certain neumnal populations in the central nervous system of the rat (1, 3-6, 8, 13, 16, 17) and the human (6)). Previous studies of the rat have shown the distribution of the NGF (1, 8, 15-17, 25), the NGF messenger RNA (1, 6, 14-16), and the NGF receptor (12, 13, 24-26, 28) in immature (1,26), young adult (6, 12, 14, 15, 2426), and the aged rat brain (8, 13, 16, 17). Of additional interest, it has been reported that cholinergic neurons in the basal forebrain expressing the NGF receptor (12, 24, 28) particularly respond to NGF by an increased level of choline acetyltransferase activity (5). Thus neuronal atrophy and a loss of NGF receptor immunoreactivity that have been found to occur in the cholinergic forebrain neurons of aged rats are thought to correlate with a decreased level of NGF in the cholinergic target cortical area (4,13). An in~ven~cul~ infusion of NGF has actually reversed the atrophy of these neurons in aged rats (3). Several studies also have uncovered that the hippocampus and certain parts of the neocortex of the young adult rat contain a considerably high level of NGF (15, 16, 29, but in some of the reports the NGF level in these regions apparently fluctuates with aging (8, 16, 17). We have found a male-female difference as well in the NGF levels in the mouse brain and spinal cord, the levels in the male being higher than in females (10,ll).
Thus the aim of the present study was to elucidate the ageand sex-related NGF dis~bution profiles in the rat brain. A sensitive two-site enzyme immunoassay using a specific antibody for the p subunit of the mouse 7s NGF(p-NGF) was applied to measure the NGF level in the discrete brain regions of young and aged rats of Wistar strain. METHOD
Male and female Wistar rats were purchased at 6-8 weeks of age (Takasugi Co., Kasukabe) and housed in our laboratory. Tbey were used at the age of 12 weeks (3 months), 16 weeks (4 months), or at 24 to 26 months (the aged rats). Tissues were taken from the olfactory bulb, the frontal cortex, the occipital cortex, the hip~~pus consisting of CA1 and 4 fields and the dentate gyms, the ventral pallidum, the septum, the stxiatum, the hypothalamus, the substantia nigral-ventral tegmental area, and the cerebellum following the atlas by Paxinos and Watson (23). These tissues were weighed and stored at - 80°C until they were assayed. Since the tumoral pituitary gland was pressing the hypothalamus in the aged female rats, the hypothalamic tissue samples were not collected fmm the aged females. The contents of endogenous p-NGF in these tissues were detetined by the two-site enzyme immunoassay which was iden-
‘Requests for reptints should be addressed to Masako Nishizuka, Ph.D., Department of Anatomy, Juntendo University School of Medicine, 2 Hongo, Tokyo 113 Japan.
685
NISHIZUKA ET AL.
686
‘aCtOry
Jib
Frontal cortex
OcclpM cortex
campus
thalamus
FIG, 1. Concentrations (mean 2 SEM, ngig wet tissue weight) of NGF in ten brain regions in the male rat at 3, 4 or 24-26 months of age. The number at the bottom of each column shows the number of rats examined. Differences from the opposite sex at the same age (Fig. 2), *p
Brain Research Bulkfin, Vol. 27, PP. 685-688. 0 Pergamon Press plc, 1991. Printed in the U.S.A
RAPID COMMUNICATION
Age- and Sex-Related Differences in the Nerve Growth Factor Distribution in the Rat Brain MASAKO NISHIZUKA,*’ RITSUKO KATOH-SEMBA,? KOU ETO,I. YASUMASA ARAI,* REIJI IIZUKA$ AND KANEFUSA KATO$ Lkpartments
of *Anatomy and $Psychiatry, Jiantendo ~niversi~ School @Medicine, Hongo, Tokyo 113 Japan and Depar~e~ts of ~Peri~tology and §E~o~hern~s~, institute for Developmental Research Aichi Prefecture Colony, Kasugai, Aichi 480-03 Japan
Received 24 June 1991 K. ETO, Y. ARAI, R. IIZUKA AND K. KATO. Age- and sex-r&fed ~i~fe~e~ in of the nerve growth factor (NGF) have been measured in various brain regions of young and aged male and female rats of Wistar strain by means of a highly sensitive two-site enzyme immunoassay system for P-NGF. Among the ten regions examined, the amount of NGF per wet weight of tissue was found to be highest in the hippocampus, irrespective of the sex and age. The NGF concentration in the hippocampus of female rats at 3 months of age was comparable to that of same age males. Further, there was no significant difference in the NGF leveis of the hippocampus between young and aged males. However, the NGF level was significantly lower in aged females as compared to that in 3- or 4-Mona-old females, and hence the marked male-female difference was found in the NGF levels in aged Wistar rats. NISHIZLKA, M., R. ATOM-SE~A, &e nerve grmvrh&for
~~~f~jbuf~~~ in the rat bruin. BRAIN RES BULL 27(S) 685-688, 1991. -Levels
Nerve growth factor
Aging
Sex difference
Enzyme immunoassay
THE nerve growth factor (NW) is important to the development (1, 4, 26) and aging (3, 4, 6, 8, 13, 16, 17) of certain neumnal populations in the central nervous system of the rat (1, 3-6, 8, 13, 16, 17) and the human (6)). Previous studies of the rat have shown the distribution of the NGF (1, 8, 15-17, 25), the NGF messenger RNA (1, 6, 14-16), and the NGF receptor (12, 13, 24-26, 28) in immature (1,26), young adult (6, 12, 14, 15, 2426), and the aged rat brain (8, 13, 16, 17). Of additional interest, it has been reported that cholinergic neurons in the basal forebrain expressing the NGF receptor (12, 24, 28) particularly respond to NGF by an increased level of choline acetyltransferase activity (5). Thus neuronal atrophy and a loss of NGF receptor immunoreactivity that have been found to occur in the cholinergic forebrain neurons of aged rats are thought to correlate with a decreased level of NGF in the cholinergic target cortical area (4,13). An in~ven~cul~ infusion of NGF has actually reversed the atrophy of these neurons in aged rats (3). Several studies also have uncovered that the hippocampus and certain parts of the neocortex of the young adult rat contain a considerably high level of NGF (15, 16, 29, but in some of the reports the NGF level in these regions apparently fluctuates with aging (8, 16, 17). We have found a male-female difference as well in the NGF levels in the mouse brain and spinal cord, the levels in the male being higher than in females (10,ll).
Thus the aim of the present study was to elucidate the ageand sex-related NGF dis~bution profiles in the rat brain. A sensitive two-site enzyme immunoassay using a specific antibody for the p subunit of the mouse 7s NGF(p-NGF) was applied to measure the NGF level in the discrete brain regions of young and aged rats of Wistar strain. METHOD
Male and female Wistar rats were purchased at 6-8 weeks of age (Takasugi Co., Kasukabe) and housed in our laboratory. Tbey were used at the age of 12 weeks (3 months), 16 weeks (4 months), or at 24 to 26 months (the aged rats). Tissues were taken from the olfactory bulb, the frontal cortex, the occipital cortex, the hip~~pus consisting of CA1 and 4 fields and the dentate gyms, the ventral pallidum, the septum, the stxiatum, the hypothalamus, the substantia nigral-ventral tegmental area, and the cerebellum following the atlas by Paxinos and Watson (23). These tissues were weighed and stored at - 80°C until they were assayed. Since the tumoral pituitary gland was pressing the hypothalamus in the aged female rats, the hypothalamic tissue samples were not collected fmm the aged females. The contents of endogenous p-NGF in these tissues were detetined by the two-site enzyme immunoassay which was iden-
‘Requests for reptints should be addressed to Masako Nishizuka, Ph.D., Department of Anatomy, Juntendo University School of Medicine, 2 Hongo, Tokyo 113 Japan.
685
NISHIZUKA ET AL.
686
‘aCtOry
Jib
Frontal cortex
OcclpM cortex
campus
thalamus
FIG, 1. Concentrations (mean 2 SEM, ngig wet tissue weight) of NGF in ten brain regions in the male rat at 3, 4 or 24-26 months of age. The number at the bottom of each column shows the number of rats examined. Differences from the opposite sex at the same age (Fig. 2), *p
