Moderate Hypogonadism Enhances Hippocampal Neurotransmission, Augments Memory and Learning and Modulates Neurogenesis in Adult Male Rats. | ||
| Bulletin of Egyptian Society for Physiological Sciences | ||
| Article 13, Volume 30, Issue 2, June 2010, Pages 213-228 PDF (218.54 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/besps.2010.36309 | ||
| Author | ||
| Ahmed Shehata* | ||
| Department of Physiology- National Organization for Drug Control and Research- Giza- Egypt | ||
| Abstract | ||
| The study aimed to test whether the decrease in testosterone level during aging is the underlying mechanism for the deterioration in memory and cognitive functions. This was achieved through determination of hippocampal neurotransmission by in vivo determination of extracellular dopamine and serotonin in CA1 hippocampal region and brain derived neurotorphic factor (BDNF) synthesis in both normal and unilateral castrated rats (an experimental model for hypogonadism) and 2 and 4 days after single dose of exemestane (5mg/kg, p.o.). In addition, learning and memory processes were determined using Morris water maze. Results showed that unilateral castration resulted in significant decrease in testosterone level, disturbing the testosterone/estradiol ratio and enhanced hippocampal neurotransmission. Besides, these effects were accompanied with an enhanced learning and memory and significant decrease in the level of BDNF expression. Whereas, exemestane treatment increased testosterone level and inhibited DA and 5-HT release, significantly increased BDNF expression and inhibited learning and memory processes in both normal and unilateral castrated groups. The study indicated that moderate hypogonadism has a positive effect on hippocampal neurotransmission, learning and memory due to the imbalance of testosterone/estradiol in favor of estradiol. On the other hand, exemestane effects might be due to imbalance of testosterone/estradiol ratio in favor of testosterone. In addition, it seems that the beneficial effects of physiological levels of testosterone are indirectly due its conversion to estradiol. Moreover, the study indicated that moderate decline in endogenous testosterone in healthy aged individuals is not the underlying mechanism of the age-related deterioration in the cognitive function. | ||
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