Effect of cyclic versus continuous hormonal replacement therapy on the structure of dentate gyrus of ovariectomized adult albino rats: a histological and immunohistochemical study

Introduction Hormonal replacement has been implicated as a possible therapeutic agent for ameliorating age-related cognitive decline in postmenopausal women. Estrogen in particular enhanced learning and memory in many women by improving the function of hippocampus after menopause. However, there is lack of studies concerning the most effective way of replacement therapy. Aim The aim of the study was to investigate the effect of hormonal replacement on the structure of dentate gyrus and to assess the most effective therapy regimen. Materials and methods Thirty six adult female albino rats were used in the study and were divided into four groups: the control group, the ovariectomized group, the ovariectomy and continuous estrogen+progesterone group, and the ovariectomy and cyclic estrogen+progesterone group. All rats were sacrificed after 5 months from the beginning of therapy. Coronal brain specimens were obtained, processed into paraffin blocks, and subjected to histological, immunohistochemical, histomorphometric, and statistical studies. Results Ovariectomy resulted in neurodegenerative changes in the dentate gyrus. These changes were partially reversed by continuous hormonal therapy; however, cyclic method of therapy was more effective. Conclusion and recommendations Cyclic hormonal therapy was proven to be more effective than continuous method after ovariectomy. Hence, it is recommended to use the cyclic method of hormonal therapy for after menopause.