Androgen transformation into estrogens through the aromatase enzyme, occurring in the rat hypothalamus during fetal life, leads to male-specific sexual differentiation of brain. Aromatase shows a peak of expression and activity in a limited period during late gestation; however, the possible dimorphism in its expression during embryogenesis is unclear. One of the mechanisms controlling tissue-specific aromatase expression might be the formation of transcript variants, that differ in the 5'-untranslated regions (5'-UTR). Exon If is the major 5'-UTR used in rodent hypothalamic-preoptic area, with low amounts of other variants encoded by different exons I also present. Another enzymatic conversion, possibly involved in brain differentiation, is the 5 alpha-reduction of Testosterone to DHT, catalyzed by two 5 alpha-reductases (5 alpha-R type1 and 2). Aim of the present study is to evaluate, in parallel, by semiquantitative RT-PCR, the dimorphic profile of the three enzymes and the pattern of the brain-specific aromatase expression in male and female rats from gestation-day 16 to postnatal-day 5 (or 15 only for 5 alpha-R1). It has been observed that, in both sexes, 5 alpha-R1 is significantly higher around birth than prenatally, and that 5 alpha-R2 expression appears to be higher in males than in females, particularly just after birth. Moreover, aromatase has two expression peaks, that are male-specific, before and after birth; only exon If is used in males, while different transcripts might be present in females postnatally. It is concluded that rodent brain sexual differentiation probably involves the activation of both 5 alpha-R2 and aromatase enzymes in a sex- and time-specific pattern.
Dimorphic expression of testosterone metabolizing enzymes in the hypothalamic area of developing rats / A. Colciago, F. Celotti, A. Pravettoni, O. Mornati, L. Martini, P. Negri-Cesi. - In: BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH.. - ISSN 0165-3806. - 155:2(2005 Mar), pp. 107-116.
|Titolo:||Dimorphic expression of testosterone metabolizing enzymes in the hypothalamic area of developing rats|
COLCIAGO, ALESSANDRA (Primo)
CELOTTI, FABIO MARIA (Secondo)
MARTINI, LUCIANO (Penultimo)
NEGRI CESI, PAOLA (Ultimo)
|Parole Chiave:||5alpha-Reductase; Arom exon If; Aromatase; Rat brain; Sex differentiation|
|Settore Scientifico Disciplinare:||Settore MED/04 - Patologia Generale|
Settore BIO/09 - Fisiologia
|Data di pubblicazione:||mar-2005|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/j.devbrainres.2004.12.003|
|Appare nelle tipologie:||01 - Articolo su periodico|