Hum. Reprod. Advance Access originally published online on December 7, 2006
Human Reproduction 2007 22(3):756-765; doi:10.1093/humrep/del454
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Cathine, an amphetamine-related compound, acts on mammalian spermatozoa via 
1- and 
2A-adrenergic receptors in a capacitation state-dependent manner
1 Division of Reproduction and Endocrinology, School of Biomedical and Health Sciences, King's College London, London, UK
2 To whom correspondence should be addressed at: Division of Reproduction and Endocrinology, School of Biomedical and Health Sciences, King's College London, London SE11UL, UKTel: 44 20 7848 6272; Fax: 44 20 7848 6220; E-mail: lynn.fraser{at}kcl.ac.uk
BACKGROUND: Mammalian spermatozoa have been shown to have 
1,2,3- and 
2A-adrenergic receptors, the former functioning only in uncapacitated spermatozoa and the latter only in capacitated cells. Cathine, an amphetamine-related metabolite of a compound found in Catha edulis leaves, accelerates capacitation and inhibits spontaneous acrosome loss by regulating cAMP production. This study tested the hypothesis that adrenergic receptors are involved in these responses.
METHODS: Uncapacitated and capacitated mouse sperm suspensions were incubated with cathine ± specific antagonists for 2- and -adrenergic receptors for 35 min, then assessed using chlortetracycline fluorescence. Reversibility of receptor accessibility was assessed by depleting suspensions of endogenous decapacitation factor (DF) and then adding crude DF with/without cathine and antagonists. Effects on tyrosine phosphorylation and calcium requirements for both ligand binding and biological responses were also evaluated.
RESULTS: Cathine's acceleration of capacitation was blocked by a 1-antagonist, whereas an 2-antagonist blocked inhibition of acrosome reactions. Cathine accelerated capacitation in decapacitated cells, a response inhibited by a 1-antagonist; cathine also stimulated tyrosine phosphorylation. Although calcium was not required for binding, it was needed for responses.
CONCLUSIONS: Cathine acts at 1-adrenergic receptors in uncapacitated spermatozoa and at 2A-receptors in capacitated cells; biological activity requires calcium but binding does not. Adrenergic receptor-binding sites can be made reversibly accessible/inaccessible by changing the capacitation state of spermatozoa. These results suggest that amphetamine-related compounds might enhance chances of fertilization in vivo.
Key words: amphetamine/capacitation/fertility/membrane-associated adenylyl cyclase/tyrosine phosphorylation
Submitted on August 18, 2006; resubmitted on October 24, 2006; accepted on October 26, 2006.
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