IN-VITRO EFFECTS OF SUBSTANCE-P AND ARGININE-VASOPRESSIN ON TESTOSTERONE PRODUCTION IN LEYDIG-CELLS OF SHORT AND LONG PHOTOPERIODIC HAMSTERS

The aim of the present study was to determine the interaction between substance P (SP) and arginine-vasopressin (AVP) on basal and LH-stimul ated testosterone production by Leydig cells isolated from hamsters ke pt under long or short days (LD-hamsters, SD-hamsters, respectively). SP inhibited the testosterone production of Leydig cells, its effect b eing more pronounced in the case of LH-stimulated steroidogenesis in L D-hamsters. Similarly, the addition of AVP to the culture medium resul ted in a diminution of basal, as well as LH-stimulated testosterone se cretions. When Leydig cells were co-incubated with SP (10(-7) M) and A VP (10(-7) M), a strong inhibition of the testosterone production by 5 0-60% was established in LD-animals. However, even within the experime ntal circumstances in SD-hamsters, the modulation of testosterone prod uction by SP and AVP was evident. The reported results suggest that th ere is an interference of two regulatory pathways, namely photoperiodi c dependence and paracrine control of testicular steroidogenesis in ha msters.