Changes of AChE activity in ovarian nerves of pigs in different periods of the oestrous cycle: relationship to ovarian steroids.

The morphological features of cholinergic nerves in the ovary, a determination of the level of acetylcholinesterase activity in different periods of the oestrous cycle and an attempt to determine if a relationship existe between AChE activity and the hormonal state of animal are described in this paper. Mature pigs were randomly assigned to 3 experimental groups and killed on 1st to 2nd d of oestrous cycle (group I; n = 6), on 13th to 14th d (group II; n = 7), and 16th to 18th d of the oestrous cycle (group III; n = 6). First signs of oestrus were designated the zeroth d. Histochemical evaluation of the most abundant cholinergic innervation was shown in ovaries of animals in group III, weaker cholinergic representation was found in animals of group I, and weakest in group II. Whereas the lowest activity of AChE determined by biochemical test was observed in the ovaries of group I, AChE activity in the ovaries on 13 to 14 and 16 to 18 d of oestrous cycle was 8- to 10-fold higher, respectively, in relation to the animals of group I. These results suggest that there exists a relationship between AChE activity in the ovary and ovarian steroid hormones and that this may be an important factor regulating the ovarian blood flow in the course of oestrous cycle in pigs.