Testosterone decreases CA1 plasticity in vivo in gonadectomized male rats

Abstract

Estrogen has been reported to enhance CA1 functional plasticity in adult rats, as measured by the induction of long-term potentiation (LTP). In the present study, the effects of androgens on CA1 LTP were assessed in adult male Sprague-Dawley rats in vivo following peripubertal castration. Castrated rats with cholesterol implants showed significantly greater plasticity, both in degree and duration of potentiation, than castrated rats given testosterone or dihydrotestosterone implants. An LTP paradigm reported to produce decremental LTP in vitro produced nondecremental LTP in androgen-deprived rats, but decremental LTP in androgen-treated rats. These results suggest that androgens, unlike estrogens, act to reduce CA1 plasticity in the adult rat.

GABA<sub>b</sub> Receptor Antagonist (CGP<sub>35348</sub>) Improves Testosterone Induced Spatial Acquisition Impairment in Adult Male Rat

“…The androgen-induced reduction of CAILTP found in previous study [9] was consistent with earlier reports that Testosterone, possibly via the AR, down regulated the NMDA receptor in CA 1 in the rat [10]. An organizational role for androgens in the reduction of NMDA-mediated synaptic plasticity in another species had been demonstrated [11].…”

GABA<sub>b</sub> Receptor Antagonist (CGP<sub>35348</sub>) Improves Testosterone Induced Spatial Acquisition Impairment in Adult Male Rat

“…The androgen-induced reduction of CAILTP found in previous study [9] was consistent with earlier reports that Testosterone, possibly via the AR, down regulated the NMDA receptor in CA 1 in the rat [10]. An organizational role for androgens in the reduction of NMDA-mediated synaptic plasticity in another species had been demonstrated [11].…”

Dihydrotestosterone Increases Hippocampal N-Methyl-d-Aspartate Binding But Does Not Affect Choline Acetyltransferase Cell Number in the Forebrain or Choline Transporter Levels in the CA1 Region of Adult Male Rats

“…DHT has been shown to increase the duration of action potentials in the CA1 region and decrease the amplitude of the afterhyperpolarization, suggesting that DHT increases hippocampal excitability (57). Interestingly, DHT has been reported to decrease LTP in the CA1 region of the hippocampus in adult male rats (58). It should be noted, however, that these males experienced chronic DHT treatment for up to 43 d. It is possible that the more acute treatment protocol used in the present study, which has been shown to increase spine synapses (22), may result in enhanced LTP.…”

Photoperiod-mediated impairment of long-term potention and learning and memory in male white-footed mice

“…Testosterone impairs CA1 LTP in rats (Harley et al, 2000) and alters hippocampal synaptic plasticity in Mus (Sakata et al, 2000). Although species differences among rodents in the effects of testosterone on hippocampal function and LTP remain unspecified, the present study argues against testosterone impairing hippocampal LTP in white-footed mice, as the SD mice (low testosterone) reduced LTP.…”

GABA<sub>b</sub> Receptor Antagonist (CGP<sub>35348</sub>) Improves Testosterone Induced Spatial Acquisition Impairment in Adult Male Rat

“…The androgen-induced reduction of CAILTP found in previous study [9] was consistent with earlier reports that Testosterone, possibly via the AR, down regulated the NMDA receptor in CA 1 in the rat [10]. An organizational role for androgens in the reduction of NMDA-mediated synaptic plasticity in another species had been demonstrated [11].…”

Dihydrotestosterone Increases Hippocampal N-Methyl-d-Aspartate Binding But Does Not Affect Choline Acetyltransferase Cell Number in the Forebrain or Choline Transporter Levels in the CA1 Region of Adult Male Rats

“…DHT has been shown to increase the duration of action potentials in the CA1 region and decrease the amplitude of the afterhyperpolarization, suggesting that DHT increases hippocampal excitability (57). Interestingly, DHT has been reported to decrease LTP in the CA1 region of the hippocampus in adult male rats (58). It should be noted, however, that these males experienced chronic DHT treatment for up to 43 d. It is possible that the more acute treatment protocol used in the present study, which has been shown to increase spine synapses (22), may result in enhanced LTP.…”

Photoperiod-mediated impairment of long-term potention and learning and memory in male white-footed mice

“…Testosterone impairs CA1 LTP in rats (Harley et al, 2000) and alters hippocampal synaptic plasticity in Mus (Sakata et al, 2000). Although species differences among rodents in the effects of testosterone on hippocampal function and LTP remain unspecified, the present study argues against testosterone impairing hippocampal LTP in white-footed mice, as the SD mice (low testosterone) reduced LTP.…”

GABA<sub>b</sub> Receptor Antagonist (CGP<sub>35348</sub>) Improves Testosterone Induced Spatial Acquisition Impairment in Adult Male Rat

“…The androgen-induced reduction of CAILTP found in previous study [9] was consistent with earlier reports that Testosterone, possibly via the AR, down regulated the NMDA receptor in CA 1 in the rat [10]. An organizational role for androgens in the reduction of NMDA-mediated synaptic plasticity in another species had been demonstrated [11].…”

Dihydrotestosterone Increases Hippocampal N-Methyl-d-Aspartate Binding But Does Not Affect Choline Acetyltransferase Cell Number in the Forebrain or Choline Transporter Levels in the CA1 Region of Adult Male Rats

“…DHT has been shown to increase the duration of action potentials in the CA1 region and decrease the amplitude of the afterhyperpolarization, suggesting that DHT increases hippocampal excitability (57). Interestingly, DHT has been reported to decrease LTP in the CA1 region of the hippocampus in adult male rats (58). It should be noted, however, that these males experienced chronic DHT treatment for up to 43 d. It is possible that the more acute treatment protocol used in the present study, which has been shown to increase spine synapses (22), may result in enhanced LTP.…”

Photoperiod-mediated impairment of long-term potention and learning and memory in male white-footed mice

“…Testosterone impairs CA1 LTP in rats (Harley et al, 2000) and alters hippocampal synaptic plasticity in Mus (Sakata et al, 2000). Although species differences among rodents in the effects of testosterone on hippocampal function and LTP remain unspecified, the present study argues against testosterone impairing hippocampal LTP in white-footed mice, as the SD mice (low testosterone) reduced LTP.…”