ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Previous studies indicated that gonadal steroids can induce changes in both motor and sensory aspects of the electrosensory system of weakly electric fish: androgens decrease the electric organ discharge frequencies and electroreceptor best frequencies of the South American gymnotoidSternopygus. The relationship between these two effects, however, was not known. In the present study, electric organ discharges (EODs) ofSternopygus dariensis were eliminated by means of spinal cord transections. This was done in order to allow an independent assessment of the influences of gonadal steroids upon electroreceptor tuning and those structures in the CNS responsible for establishing the discharge frequency. Transection alone affected neither the rhythmic discharges of the pacemaker nucleus that normally controls the discharge frequency, nor the best frequencies of electroreceptors. Similarly, administration of the androgen 5α-dihydrotestosterone (DHT) to transected animals also had no significant effect upon electroreceptor tuning. DHT did, however, cause significant decreases in the discharge rates of the pacemaker nucleus. Thus, the effects of gonadal steroids upon discharge frequencies in intact animals are a direct consequence of CNS influences, while effects upon electroreceptor tuning likely arise as a secondary consequence of the changed discharges of hormone-treated animals.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01350215
