The Effects of Estrogens on Learning in Rats with Chronic Brain Cholinergic Deficiency in a Morris Water Test. Identification of the “Passive Swimming” Component

Abstract

Chronic decreases in brain cholinergic functions due to intraventricular administration of the neurotoxin AF64A were accompanied by increases in the latent period of locating an invisible platform during training of rats in a Morris water test, as compared with control sham-operated animals. Recordings of the animals' movement trajectories using a video camera along with an original computer program (Behavioral Vision) showed that administration of 17beta-estradiol and its synthetic analog J-861 (0.2 mg/kg p.o. daily for seven days before and 10 days after single intraventricular injections of AF64A) improved learning. The directivity of platform search trajectories was assessed quantitatively using a new parameter--trajectory straightness. Introduction of the "passive swimming" parameter allowed periods of immobility in water to be identified within the total latent period in animals after administration of AF64A; 17beta-estradiol but not J-861 "eliminated" these periods. The new parameters (especially trajectory straightness) allowed the ability to learn to be discriminated from decreases in mobility, including mobility losses due to study agents, in the Morris water test.

Effects of estrogens on cholinergic neurons in the rat basal nucleus

“…Both E 2 and J 861 have antioxidant properties [23] and neuroprotective actions [47]. E 2 exerts those effects via several mechanisms: (1) as a classical intracellular receptor acting on transcription; (2) as a mediator between secondary messengers in intracellular process; and (3) by mechanisms affecting membrane receptors and ion channels [48].…”

Effect of 17b-estradiol on bioenergetic processes in the heart mitochondria of ovariectomized rats with insulin resistance

“…17b-эстрадиол вводили внутрижелудочно с помощью зонда в дозе 0,2 мг/кг массы тела в виде водной суспензии, стабилизированной Твином-80, один раз в сутки в течение восьми недель, начиная с первого дня эксперимента [7]. Контрольная группа животных с инсулино-резистентностью получала аналогичный объём растворителя (плацебо).…”