Dendritic spine density of posterodorsal medial amygdala neurons can be affected by gonadectomy and sex steroid manipulations in adult rats: a Golgi study.
The posterodorsal medial amygdala (MePD) is a sex steroid-responsive area in the rat brain. The dendritic spine density of Golgi-impregnated MePD neurons were studied in: (1) adult gonadectomized (GDX) males after a short or a longer postcastration period (8 and 90 days, respectively), compared to age-matched sham operated and to intact controls; (2) adult GDX females, which received oil, estradiol benzoate (EB) alone or EB and progesterone as substitutive therapy; and, (3) EB-treated GDX females that concomitantly received saline or LY235959, a competitive antagonist of NMDA receptors, to test a possible glutamatergic mediation on the estrogen-mediated increase in spine density in this brain area. Intact males showed a higher spine density than males studied 8 days after sham operation or those in both short- and long-term GDX groups (p<0.02), but not when compared to males at 90 days after sham operation (p=0.12). In females, dendritic spine density increased following EB injections when compared to the oil group (p=0.05), with an effect that was potentiated by progesterone (p<0.01). LY235959 was not able to block the stimulating effect of EB on dendritic spines of GDX females (p>0.2). These data provide novel evidence that MePD dendritic spines are affected by sex steroid manipulations in adult rats, GDX males had a specific spine density decrease after a long postcastration period, and estrogen (apparently independently of a NMDA receptor interaction) and progesterone have stimulatory effects on the number of dendritic spines in GDX females.
de Castilhos
Juliana
J
Department of Morphological Sciences, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Forti
Claudia D
CD
Achaval
Matilde
M
Rasia-Filho
Alberto A
AA
D000679:Amygdala / Q000166:cytology* / Q000187:drug effects; D000818:Animals; D002369:Castration; D049229:Dendritic Spines / Q000187:drug effects / Q000648:ultrastructure*; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D007091:Image Processing, Computer-Assisted; D008297:Male; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D016622:Silver Staining
C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol