Effects of acute and chronic administration of neurosteroid dehydroepiandrosterone sulfate on neuronal excitability in mice

Figures & data

Table 1 The effects of higher DHEAS doses (25 and 50 mg/kg) on the seizure thresholds for PTZ, picrotoxin, and NMDA in adult male and female mice

Seizure threshold	Myoclonus	RB	THE
PTZ (mg/kg)
Control male mice	29.59±0.58	33.03±0.89	52.90±3.41
Control female mice	31.67±0.79	36.93±0.80	53.06±2.40
DHEAS-treated male mice (25 mg/kg)	31.19±1.65	34.69±1.97	42.36±2.99
DHEAS-treated female mice (25 mg/kg)	29.50±2.60	34.12±2.82	46.33±4.29
DHEAS-treated male mice (50 mg/kg)	27.98±1.79	31.21±2.10	47.94±5.80
DHEAS-treated female mice (50 mg/kg)	31.04±1.81	34.71±1.90	43.53±1.60
Picrotoxin (mg/kg)
Control male mice	–	21.17±0.34	28.28±0.98
Control female mice	–	25.62±1.62	35.63±1.69
DHEAS-treated male mice (25 mg/kg)	–	19.01±0.66	27.80±1.04
DHEAS-treated female mice (25 mg/kg)	–	23.66±0.64	32.81±0.78
DHEAS-treated male mice (50 mg/kg)	–	19.57±0.50	27.83±0.51
DHEAS-treated female mice (50 mg/kg)	–	23.52±0.30	36.17±1.66
NMDA (mg/kg)
Control male mice	–	185.5±6.15	223.8±6.09
Control female mice	–	203.6±22.31	293.4±16.49
DHEAS-treated male mice (25 mg/kg)	–	194.9±8.26	236.0±7.28
DHEAS-treated female mice (25 mg/kg)	–	191.8±3.95	286.3±4.73
DHEAS-treated male mice (50 mg/kg)	–	171.6±5.91	213.9±7.18
DHEAS-treated female mice (50 mg/kg)	–	222.4±8.43	310.8±7.96

Notes: Saline (control group) and 25 and 50 mg/kg of DHEAS were administered intraperitoneally to mice 30 minutes prior to the intravenous infusion of convulsant. The observed convulsive signs – myoclonus, RB, and THE. The values represent mean ± SEM from seven animals per group.

Abbreviations: DHEAS, dehydroepiandrosterone sulfate; NMDA, N-methyl-D-aspartate; PTZ, pentylenetetrazole; RB, running and bouncing clonus; SEM, standard error of the mean; THE, tonic hindlimb extension.

Figure 1 The effects of acute DHEAS treatment on the seizure thresholds for (A and B) PTZ, (C and D) picrotoxin, and (E and F) NMDA in adult male and female mice.

Notes: Saline (control group) or 10 mg/kg of DHEAS was administered intraperitoneally to mice 30 minutes prior to the intravenous infusion of convulsant. The observed convulsive signs – myoclonus, RB, and THE. The bars represent mean ± SEM from seven to eight animals per group.
Abbreviations: DHEAS, dehydroepiandrosterone sulfate; NMDA, N-methyl-D-aspartate; PTZ, pentylenetetrazole; RB, running and bouncing clonus; SEM, standard error of the mean; THE, tonic hindlimb extension.

Figure 2 The effects of acute DHEAS treatment on the seizure thresholds for picrotoxin in aged (A) male and (B) female mice.

Notes: Saline (control group) or DHEAS (10 mg/kg) was administered intraperitoneally to mice 30 minutes prior to the intravenous infusion of picrotoxin. The observed convulsive signs – RB and THE. The bars represent mean ± SEM from seven animals per group.
Abbreviations: DHEAS, dehydroepiandrosterone sulfate; RB, running and bouncing clonus; SEM, standard error of the mean; THE, tonic hindlimb extension.

Figure 3 The effects of chronic DHEAS treatment on the seizure thresholds for (A and B) PTZ, (C and D) picrotoxin, and (E and F) NMDA in adult male and female mice.

Notes: Saline (control group) or DHEAS (10 mg/kg) was administered intraperitoneally to adult mice once daily for 4 consecutive weeks. On the last day of chronic treatment, intravenous infusion of convulsant started 30 minutes following last DHEAS or saline administration. The observed convulsive signs – myoclonus, RB, and THE. The bars represent mean ± SEM from seven to eight animals per group.
Abbreviations: DHEAS, dehydroepiandrosterone sulfate; NMDA, N-methyl-D-aspartate; PTZ, pentylenetetrazole; RB, running and bouncing clonus; SEM, standard error of the mean; THE, tonic hindlimb extension.

Figure 4 The sex differences in the effects of acute and chronic DHEAS treatment on the seizure thresholds for (A and C) PTZ, (D and E) picrotoxin, and (F and G) NMDA in adult mice.

Notes: Saline (control group) or DHEAS (10 mg/kg) was administered to adult male and female mice intraperitoneally 30 minutes prior to the intravenous infusion of convulsant (acute treatment) or once daily for 4 consecutive weeks (chronic treatment). The observed convulsive signs – myoclonus, RB, and THE. The dots represent mean ± SEM from seven to eight animals per group. *P<0.05; **P<0.002 versus male mice (Student’s t-test).
Abbreviations: DHEAS, dehydroepiandrosterone sulfate; NMDA, N-methyl-D-aspartate; PTZ, pentylenetetrazole; RB, running and bouncing clonus; SEM, standard error of the mean; THE, tonic hindlimb extension.

Table 2 The sex and age differences in the effects of acute DHEAS treatment on the seizure thresholds for picrotoxin in mice

Seizure threshold picrotoxin (mg/kg)	RB	THE
Adult control male mice	21.88±0.76	28.28±0.98
Adult control female mice	25.62±1.62	35.63±1.69
Adult DHEAS-treated male mice (10 mg/kg)	19.59±0.41	27.50±0.91
Adult DHEAS-treated female mice (10 mg/kg)	23.32±0.79	33.89±0.94
Aged control male mice	16.33±0.47**	26.56±2.37
Aged control female mice	12.79±0.53ψ,***	26.76±0.74***
Aged DHEAS-treated male mice (10 mg/kg)	14.38±0.58***	22.34±3.76
Aged DHEAS-treated female mice (10 mg/kg)	13.13±0.56***	27.40±1.88**

Notes: Saline (control group) or 10 mg/kg of DHEAS were administered intraperitoneally to adult and aged mice of both sexes, 30 minutes prior to the intravenous infusion of picrotoxin. The observed convulsive signs – RB and THE. The values represent mean ± SEM from seven animals per group.

ψ P<0.02 aged control female versus male mice;

** P<0.01;

*** P<0.0004 adult versus aged mice of the same sex and group (Student’s t-test).

Abbreviations: DHEAS, dehydroepiandrosterone sulfate; RB, running and bouncing clonus; SEM, standard error of the mean; THE, tonic hindlimb extension.

Table 3 The effects of acute and chronic DHEAS treatment on locomotor activity of adult male and female mice

Locomotor activity (counts/10 min)	Acute (10 mg/kg) DHEAS treatment	Chronic (10 mg/kg) DHEAS treatment
Control male mice	536.00±30.99	522.50±27.45
Control female mice	592.00±19.52	575.00±35.72
DHEAS-treated male mice	614.00±24.24	587.40±30.30
DHEAS-treated female mice	622.10±26.35	644.30±25.02

Notes: The locomotor activity of adult male and female mice was recorded for 10 minutes in the test cage, 30 minutes following single (acute treatment) or the last (after 4 consecutive weeks of chronic treatment) DHEAS (10 mg/kg) or saline intraperitoneal administration. The values represent mean ± SEM from seven to eight animals per group.

Abbreviations: DHEAS, dehydroepiandrosterone sulfate; min, minutes; SEM, standard error of the mean.

Table 4 The effects of acute and chronic DHEAS treatment on motor coordination of adult male and female CBA mice

Motor coordination	Acute (10 mg/kg) DHEAS treatment		Chronic (10 mg/kg) DHEAS treatment
	The number of falls	The latency to fall (seconds)	The number of falls	The latency to fall (seconds)
Control male mice	0.22±0.15	106.70±8.82	0.56±0.29	95.56±12.37
Control female mice	0.50±0.50	108.80±11.25	0.78±0.22	77.78±10.77
DHEAS-treated male mice	0.50±0.27	95.00±12.39	0.33±0.24	104.40±10.42
DHEAS-treated female mice	0.33±0.17	93.33±10.54	0.25±0.25	102.20±11.76

Notes: The pretrained adult male and female mice were placed on the rota-rod treadmill (constant speed of 15 rpm) 30 minutes following single (acute treatment) or the last (after 4 consecutive weeks of chronic treatment) DHEAS (10 mg/kg) or saline intraperitoneal administration. The number of falls and latency to fall was measured for up to 2 minutes. The values represent mean ± SEM from seven to eight animals per group.

Abbreviations: DHEAS, dehydroepiandrosterone sulfate; SEM, standard error of the mean.

Table 5 The effects of chronic DHEAS treatment on the body weight of adult male and female mice

Body weight (g)	First day of the treatment	Last day of the treatment
Control male mice	24.08±0.45*	24.90±0.76*
Control female mice	19.28±0.38	21.22±0.63
DHEAS-treated male mice	23.72±0.40*	25.45±0.30*
DHEAS-treated female mice	18.64±0.33	21.06±0.76ψ

Notes: Saline or DHEAS (10 mg/kg) was administered intraperitoneally to adult mice once daily for 4 consecutive weeks. The body weight of adult male and female animals was determined on the first and the last days of treatment. The values represent mean ± SEM from seven to eight animals per group.

* P<0.001, group of male mice versus corresponding group of female mice;

ψ P<0.05, DHEAS-treated female mice last day versus first day of the treatment (analysis of variance followed by Newman–Keuls test).

Abbreviations: DHEAS, dehydroepiandrosterone sulfate; SEM, standard error of the mean.

Table 6 The effects of acute DHEAS treatment on the potency of DHEAS for inhibiting [³H]flunitrazepam binding to the brain membranes of adult male and female mice

DHEAS inhibition of[^3H]flunitrazepam biding	IC50 (µM)	Imax (%)
Control male mice	53.8±10.0	65.66±1.59
Control female mice	102.1±28.0	65.56±4.35
DHEAS-treated male mice	60.8±34.8	69.60±1.56
DHEAS-treated female mice	89.2±47.4	70.93±6.04

Notes: The animals were sacrificed 30 min following the intraperitoneal administration of 10 mg/kg DHEAS or saline. Isolated brain membranes were incubated with increasing concentrations of DHEAS (1 µM to 1 mM) and fixed concentration (1 nM) of [³H]flunitrazepam. Nonspecific binding was determined in the presence of 100 µM diazepam. The inhibition curves were analyzed, and the values of half-maximum (IC₅₀) and maximum (I_max) inhibition of [³H]flunitrazepam binding produced by DHEAS were determined. The values represent mean ± SEM from three independent experiments performed in duplicate.

Abbreviations: DHEAS, dehydroepiandrosterone sulfate; IC₅₀, half-maximum inhibition; min, minutes; SEM, standard error of the mean.

Figure 5 The effects of acute DHEAS treatment on DHEAS-produced inhibition of [³H]flunitrazepam binding to the brain membranes of adult male and female mice.

Notes: The animals were sacrificed 30 minutes following intraperitoneal administration of 10 mg/kg DHEAS or saline. Isolated brain membranes were incubated with increasing concentrations of DHEAS (1 µM to 1 mM) and fixed concentration (1 nM) of [³H]flunitrazepam. Radioactivity bound to membranes after vacuum filtration was measured using β-scintillation counter. Nonspecific binding was determined in the presence of 100 µM diazepam. The inhibition curves were analyzed, and values of half-maximum and maximum inhibition of [³H]flunitrazepam binding produced by DHEAS were determined. The dots represent mean ± SEM from three independent experiments performed in duplicate.
Abbreviations: DHEAS, dehydroepiandrosterone sulfate; SEM, standard error of the mean.