Data and experimental setup for a comprehensive study of ketamine's effect on neuronal plasticity following social isolation rearing in male and female rats

Abstract

In this study, we collected electrophysiological data from acute hippocampal slices of male and female Sprague Dawley rats. Rats were exposed to social isolation rearing and then acutely treated with various doses of ketamine in order to rescue hippocampal plasticity deficits induced by isolation stress. We used two different approaches to study neuronal plasticity: Long-Term Potentiation (LTP) which is a well-established cellular model for memory and Paired-Pulse Facilitation (PPF) which is short-term of presynaptic plasticity. The aim of this article is to offer more experimental details about out LTP and PPF procedures.

Keywords: Estrous cycle; Hippocampus; Ketamine; Long term potentiation; Paired pulse facilitation; Plasticity; Sex differences; Social isolation.

Graphical abstract

Fig. 1

A) Hippocampal slice diagram for stimulating and recording electrodes’ location. B) Stimulation protocols. Synaptic transmission strength was measured by assessing the initial slope of fEPSPs using stimuli of monophasic 100 µs pulses at 0.033 Hz. The responses were tested over a range of stimulus intensities from 0.2 to 0.65 mA. LTP was induced with high frequency stimulation, including two trains of 50 square pulses (100 Hz) delivered 30 seconds apart. Baseline recordings were also obtained as reference before HFS. For PPF Two monophasic pulses of 100 µs were delivered in trials with intervals of 100ms, 50ms, and 20ms.

Fig. 2

Tissue preparation station. 1) Leica VT1200S blade vibratome. Slices containing dorsal hippocampus were cut at 400µm thickness. Cutting chamber was kept cold by filling the surrounding space with ice. 2) (Fisher Scientific Isotemp 205 Digital Water Bath. The hippocampal slices were incubated in ACSF at 37°C for 1 hour. 3) Solutions (left to right) 3M KCl, 125M NaH2PO4, 1M MgSO4, 2M CaCl.

Fig. 3

Recording equipment. Placed on a vibration isolation workstation (Burleigh Gibraltar®) surrounded by a Faraday Cage (Vibraplane platform from Kinetic Systems. 1) Tissue mount slice anchor (Warner Instruments, SHD-26H/2). 2) Nikon DS-Qi1Mc camera connected to Nikon Eclipse FN1 microscope. 3) Gravity syphon used to perfuse with ACSF (35 ± 2°C). 4) Concentric bipolar stimulating electrode (FHC CBAPC75). 5) Chlorided silver electrode (Ag/AgCl) mounted inside a pulled glass pipette.

Fig. 4

Narshige PC-10 pipette puller. The pipette pulling protocols were adjusted seasonally according to temperature and humidity, with ramp tests of the glass being done regularly to assure consistency. “The pipette cookbook” (Sutter Instrument Company, CA) was used as reference.

Fig. 5

1) Master-8 stimulus generator coupled to an AMPI Iso-Flex power box. 2 & 3. Axon Multiclamp 700B amplifier (Molecular Devices).