Research Report Effect of prenatal exposure to an anti-inflammatory drug on neuron number in cornu ammonis and dentate gyrus of the rat hippocampus: A stereological study Alpaslan Gokcimen a , Murat Çetin Rağbetli b , Orhan Baş c , Ayten Turkkanı Tunc d , Huseyin Aslan d , A. Canan Yazici e , Suleyman Kaplan f, ⁎ a Department of Histology and Embryology, Süleyman Demirel University School of Medicine, Isparta, Turkey b Department of Histology and Embryology, Yüzüncü Yıl University School of Medicine, Van, Turkey c Department of Anatomy, Kocatepe University School of Medicine, Afyon, Turkey d Department of Histology and Embryology, Gaziosmanpasa University School of Medicine, Tasliciflik Kampusu, Tokat, Turkey e Department of Biostatistics, Baskent University School of Medicine, Ankara, Turkey f Department of Histology and Embryology, Ondokuz Mayis University School of Medicine, TR-55139 Samsun, Turkey ARTICLE INFO ABSTRACT Article history: Accepted 17 October 2006 Available online 21 November 2006 Prenatal exposed to an anti-inflammatory drug is a major problem for the developing central nervous system. It is not well known the effect of prenatal exposed to a non-steroidal anti-inflammatory drug on the hippocampus. Total neuron number in one side of the cornu ammonis (CA) and gyrus dentatus (GD) of the hippocampal formation in control and drug- treated (diclofenac sodium, DS) groups of male rats was estimated using the optical fractionator technique. Each main group has also two subgroups that are 4 weeks old (4W- old) and 20 weeks old (20W-old). In CA, no significant difference between 4W-old DS-treated and their control was found, but a significant difference was observed between 20W-old DS- treated and their controls. A decreasing of neuron number was 12% for 20W-old DS-treated group. In GD, a decreasing of the granule cell number in 4W-old of DS-treated group was seen but an increasing of granule cell number was found in the 20W-old drug-treated rats in comparison to its control group, 7% and 9%, respectively. Although an increasing of neuron number in CA at the control group was seen with age, from 4th week to 20th week (10%), age- dependent substantial granule cell decline (17%) was observed in GD. No age effect on the total cell numbers of CA and GD of the drug-treated groups was seen in comparison to 4W- old week and 20W-old. A pronounced neuron loss observed in the drug-treated group may be attributed to the neurotoxicity of diclofenac sodium (DS) on the developing hippocampal formation. Age-dependent neuron increase in the CA of 20W-old and neuron decline in GD of 20W-old control groups may be a result of a dual effect of saline injection during the fetal life, since these animals were exposed to a stress of 15-day-period of saline injection, prenatal stress. The reason of no age effect on CA and GD cell number in the drug-treated groups may be attributed to the depletion of the progenitor cells due to neurotoxicity of DS in the fetal life of these animals. © 2006 Elsevier B.V. All rights reserved. Keywords: Hippocampus Nonsteroidal anti-inflammatory drug Diclofenac sodium Stereology Rat BRAIN RESEARCH 1127 (2007) 185 – 192 ⁎ Corresponding author. Fax: +90 362 312 19 19x2265. E-mail address: skaplan@omu.edu.tr (S. Kaplan). 0006-8993/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.brainres.2006.10.026 available at www.sciencedirect.com www.elsevier.com/locate/brainres