Long-term testosterone administration affects the number of paracervical ganglion ovary-projecting neurons in sexually mature gilts

Abstract

The influence of testosterone (T) overdose on the number and distribution of ovarian neurons in the paracervical ganglion (PCG) in pigs was examined. To identify the ovarian neurons, on day 3 of the estrous cycle, the ovaries of both the control and experimental gilts were injected with retrograde neuronal tracer Fast Blue. From next day to the expected day 20 of the second studied cycle, experimental gilts were injected with T, while control gilts received oil. The PCG was then collected and processed for double-labeling immunofluorescence. T injections increased the T (∼3.5-fold) and estradiol-17β (∼1.6-fold) levels in the peripheral blood, and reduced the following in the PCG: the total number of Fast Blue-positive neurons, the number of perikarya in the lateral part of the PCG, the numbers of VAChT(+)/SOM(+), VAChT(+)/VIP(+), VAChT(+)/nNOS(+), VAChT(+)/VIP(-), VAChT(+)/DβH(-), VAChT(-)/SOM(-), VAChT(-)/VIP(-), VAChT(-)/nNOS(-) and VAChT(-)/DβH(-) perikarya, In the T-affected PCG, the populations of ovarian perikarya coded VAChT(-)/SOM(+), VAChT(-)/VIP(+) and VAChT(-)/DβH(+), and expressing androgen receptor were increased. After T treatment within the PCG dropped the density of nerve fibers expressing VAChT and/or SOM, VIP, DβH. Obtained data suggest that elevated androgen levels occurring during pathological processes may regulate ovary function(s) by affecting the PCG gonad-supplying neurons.

Keywords: Hyperandrogenism; Ovarian neuron; Paracervical ganglion; Pig; VAChT.