EMF-Portal | Influence of microwave exposure on chlordiazepoxide effects in the mouse staircase test

Influence of microwave exposure on chlordiazepoxide effects in the mouse staircase test med./bio.

By: Quock RM, Klauenberg BJ, Hurt WD, Merritt JH

Published in: Pharmacol Biochem Behav 1994; 47 (4): 845-849

Aim of study (acc. to author)

To ascertain whether behavioral effects of benzodiazepines are altered by exposure to microwaves, the authors compared the performance of mice in the staircase test 30 min after pretreatment with chlordiazepoxide (8, 16, and 32 mg/kg) and immediately following a 5 min exposure to microwaves.

Background/further details

The mouse staircase test is an efficient test for preliminary assessment of anxiolytic and sedative effects of benzodiazepines.
Mice were irradiated in pairs at different specific absorption rates at a frequency of either 1.8 or 4.7 GHz (25 min after drug administration).

Endpoint

Exposure

Exposure	Parameters
Exposure 1: 1.8 GHz Modulation type: CW Exposure duration: continuous for 5 min	SAR: 4 W/kg average over mass (whole body) SAR: 12 W/kg average over mass (whole body) SAR: 36 W/kg average over mass (whole body)
Exposure 2: 4.7 GHz Modulation type: CW Exposure duration: continuous for 5 min	SAR: 4 W/kg average over mass (whole body) SAR: 12 W/kg average over mass (whole body) SAR: 36 W/kg average over mass (whole body)

Modulation type	CW

Exposure source	horn antenna anechoic chamber
Distance between exposed object and exposure source	2 m
Setup	Mice were individually held inside Plexiglas cylindrical restrainers which were placed on a table in front of the standard gain pyramidal horn antenna and exposed in E-polarisation.
Sham exposure	A sham exposure was conducted.
Additional info	Sham irradiated mice were similarly restrained and placed inside the chamber out of the EMF.

Measurand	Value	Type	Method	Mass	Remarks
SAR	4 W/kg	average over mass	measured	whole body	-
SAR	12 W/kg	average over mass	measured	whole body	-
SAR	36 W/kg	average over mass	measured	whole body	-

Dewar-flask calorimetry was used to measure the SAR [Allen and Hurt, 1979].

Modulation type	CW

Exposure source	same setup as exposure 1
Distance between exposed object and exposure source	1.46 m
Sham exposure	A sham exposure was conducted.

Measurand	Value	Type	Method	Mass	Remarks
SAR	4 W/kg	average over mass	measured	whole body	-
SAR	12 W/kg	average over mass	measured	whole body	-
SAR	36 W/kg	average over mass	measured	whole body	-

Allen SJ et al. (1979): Calorimetric Measurements of Microwave-Energy Absorption by Mice After Simultaneous Exposure of 18 Animals

Exposed system:

Methods Endpoint/measurement parameters/methodology

cognitive/behavioral endpoints: locomotor activity (staircase test: number of rears (NR); number of steps ascended (NSA))

Investigated system:

Time of investigation:

Main outcome of study (acc. to author)

In sham-exposed animals, 8 mg/kg chlordiazepoxide increased the number of steps ascended (NSA) without affecting number of rears (NR). In sham-exposed animals, 16 mg/kg chlordiazepoxide increased the number of steps ascended (NSA) and decreased the number of rears (NR). And 32 mg/kg chlordiazepoxide then decreased both the number of steps ascended (NSA) and the number of rears (NR).
Microwave irradiation generally did not alter the number of steps ascended (NSA) or the number of rears in animals pretreated with lower doses of chlordiazepoxide. However, in animals pretreated with 32 mg/kg chlordiazepoxide, exposure to 4.7 GHz at 36 W/kg microwave exposure significantly reversed the reductions in NSA and NR (cf. sham exposure),- i.e. significantly greater numbers of steps ascended (NSA) and numbers of rears (NR) were revealed. This was not the case at 1.8 GHz.
These results indicate that exposure to microwaves can selectively alter effects of chlordiazepoxide in this psychopharmacological paradigm.

Study character:

Study funded by

Brooks Air Force Base, USA