Morphometrical and microdensitometrical studies on phenylethanolamine-N-methyltransferase- and neuropeptide Y-immunoreactive neurons in the rostral medulla oblongata of the adult and old male rat.
In the present paper the neuronal systems of the medulla oblongata containing phenylethanolamine-N-methyltransferase- and neuropeptide Y-like immunoreactivity have been characterized in adult (3-month-old) and old (24-month-old) male rats. The phenylethanolamine-N-methyltransferase and neuropeptide Y-immunoreactive neurons have been visualized by means of immunocytochemistry (peroxidase-antiperoxidase technique) and analysed in a quantitative fashion by means of morphometrical (phenylethanolamine-N-methyltransferase- and neuropeptide Y-immunoreactive cell groups) and microdensitometrical (phenylethanolamine-N-methyltransferase-immunoreactive cell groups) approaches developed on the IBAS II image analyser (Zeiss-Kontron). During aging there is (a) a reduction in the area covered by the phenylethanolamine-N-methyltransferase-immunoreactive neuropil for both the C1 and C2 adrenaline cell groups; (b) a reduction in the area covered by the phenylethanolamine-N-methyltransferase-immunoreactive cell bodies, which is highly significant only for the C2 cell group; (c) a decrease in the area covered by the phenylethanolamine-N-methyltransferase-positive cell cluster for both C1 and C2 cell groups; (d) a decrease in the degree of phenylethanolamine-N-methyltransferase immunoreactivity present in the C1 and C2 cell groups; (e) a decay of neuropeptide Y immunoreactivity in the C1 and C2 groups, while the C3 group is unaffected by aging as evaluated by number of phenylethanolamine-N-methyltransferase- and neuropeptide Y-immunoreactive cell body profiles. These results indicate heterogeneities in the responses of the adrenaline-neuropeptide Y cell groups to the aging process. The possible functional consequences of aging-induced changes in the cardiovascular adrenergic neurons are discussed, especially in relation to development of hypertension.
Agnati
L F
LF
Department of Human Physiology, University of Modena, Italy.
Fuxe
K
K
Zoli
M
M
Zini
I
I
Härfstrand
A
A
Toffano
G
G
Goldstein
M
M
D000375:Aging / Q000378:metabolism*; D000818:Animals; D004837:Epinephrine / Q000378:metabolism* / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism* / Q000502:physiology; D009478:Neuropeptide Y / Q000378:metabolism* / Q000502:physiology; D010625:Phenylethanolamine N-Methyltransferase / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains
D009478:Neuropeptide Y; D010625:Phenylethanolamine N-Methyltransferase; D004837:Epinephrine