Eur J Anat, 2 (2): 101-108 (1998)

Inverse effects of estradiol and testosterone on the vitro proliferation rate of rat VIP-immunoreactive pituitary cells

J. Carretero^1,2, R.J. Vázquez², M. Rubio², M. Santos², G. Vázquez², F. Sánchez^1,2, E. Blanco^1,2, A. Martín-Clavijo² and R. Vázquez^1,2

1.-Laboratory of Neuroendocrinology, Institute of Neuroscience of Castilla y León. Faculty of Medicine, University of Salamanca. Spain2.-Department of Human Anatomy and Histology, Faculty of Medicine, University of Salamanca. Spain

ABSTRACT Using double immunocytochemicallabelling for Proliferating Cell Nuclear Antigen(PCNA)and Vasoactive Intestinal Peptíde (VIP), a stucly was conducted to el ucidate the repercussions of various closes (ranging from 10-8 to 10-5M) of estracliol 01'testosterone (fram 1 to 24 hours) aclministered to monolayer pituitary cultures on the proliferation rate, expressecl as the PCNA­ labelling inclex, of VIP-immunoreactive ce lis(PCNA-LO.The results are comparecl with those obtainee! in control cultures. Estracliol inclucecl significant increases in the percentages of PC A- and VIP-immunoreactive cells at each clase assayed as early on as one hour postadrni­ nistration. The most efficient effect was obser­ ved for 1O-5Mestradiol. For all time-points assa­ yecl, the percentages of PCNA- and VIP-immunoreactive cells were hígher than in control dishes. Similar findings were observed when percentages of VIP-immunoreactive cells were analyzed. Testosterone decreasecl the per­ centages of VIP-immunoreactive or PCNA- and VIP-immunoreactive cells with respect to con­trol dishes at all doses and time points analyzed; frorn 6 to 24 hours of treatment, the effects were less evident for 10-7 ane! 1O-8M testosterone than for the other doses assayed. The rnodifications observed in the proliferation rate ancl nurnerical density of VIP-immunoreactive cells were accornpanied by increases, in the case of estra­ diol, and decreases, in the case of testosterone,in the release of VIP to the culture médium. In conclusion, our results suggest that estradiol and testosterone have opposite effects on the relea­ se of VIP from pituitary monolayer cultures and on the regulation of the in uitro proliferation of pituitary VIP-immunoreactive cells.

Keywords: Pituitary - VIP - Gonadal steroids - Cellular proliferation - Irnmunocytochemistry