The Response of the Isolated Uterus of the Guinea‐pig to Stimulation of the Ovarian Nerves During the Oestrous Cycle

Abstract

Summary. This paper tlcscrilu'S a prfpanttion consisting of a iiitfd uterine horn with tlie ovariiin n(;r\t's attafhcd. The response to lu-rve stinmiation and to winte drugs depend.s on (he stiiKi' i>f the oestrous cycle.Uteri taken from Ruineii-piRs in dioestroius, in which the vaginal elosure membrane was intact, responded to stimulation of die nerves acxompanying the ovarian vessels witli large fontractinns. Uteri taken from guinea-pins in oe.stroiis, in which the nu-mlmine was absent, responded to stimulation with relnxatiori or irregular ox icc'l>k' coiitriiction.s Noradrcnaline iisiiiilly ciuised ion tract ion of the uterus from animals in dioestroiLs but mtt oi those in oestroiis. Adrenaline caused inhibition and ac:etylcholine contraction of uteri, irrespective of (he stage of the sexual cycle.The response of the dioestrons uterus to nerve stinuilatiim was retliiced by phentolaniine and hy Knanethidine. iiicTOiiseJ by prnpraiiolol and by cocaiiie. and was nnalfected by atropini", hyostine or hexaniethdiiiiui). It is concluded that the fibres stiinulati-d art' post nan ^;]i<)niL• and nuradrenergic. In uteri taken during oestrons the addition of proiiethalol to the bath led to the appearance of contractile responses lo nerve stinmiation, Oestrous uterine homs were often quiescent, while those taken dtiring the remainder of the cycle often exhibited spontaneous activity which griidnally increa.sed during the t'ourst; of an experiment, hnt often increased rapitlly after pheiitolamine or guanethidine wa.s adtled to the buth.The relationship between these results and tlie changing levels of ovarian hormones during the oestrous cyele is discussed.

Effects of ovarian steroids upon responses mediated by adrenoceptors in separated layers of the myometrium and in the costo‐uterine muscle of the guinea‐pig

“…The present study of the effects of ovarian steroids upon the response of the guinea-pig uterus to adrenergic influences differs from earlier studies (Hermansen, 1960;Pennefather & Isaac, 1967;Isaac et al, 1969;Russe & Marshall, 1970;Szurszewski & Builbring, 1973;Elmer, Alm & Thorbert, 1980) in that the two myometrial layers have been studied separately. This major methodological modification has allowed us to establish that the administration of progesterone to oestrogen-primed animals leads, in both ovariectomized and intact animals, to a clearcut, reproducible reversal of the effects of phenylephrine, in the longitudinal, but not in the circular myometrial layer.…”

“…These effects have been demonstrated using uterine horns from the guinea-pig (Hermansen, 1960;Pennefather & Isaac, 1967;Isaac, Pennefather & Silva, 1969;Russe & Marshall, 1970), the cat (Dale, 1906;Cushny, 1906;Gustavson & van Dyke, 1931;Tsai & Fleming, 1964), the rabbit (Miller & Marshall, 1965), and the rat (Diamond & Brody, 1966;AbdelAziz & Bakry, 1973). Electrophysiological studies with guinea-pig myometrium by Szurszewski & Billbring (1973), have done much to establish the ionic basis of the excitatory and inhibitory actions of catecholamines mediated via actions at uterine a-and 13-adrenoceptors.…”

AN in vitro COMPARISON OF β‐ADRENOCEPTOR STIMULANTS ON POTASSIUM‐DEPOLARIZED UTERINE PREPARATIONS FROM GUINEA‐PIGS

“…Pennefather & Isaac (1967) demonstrated in guinea-pig uterus that, in the presence of propranolol, noradrenaline and adrenaline produced contractions. This was confirmed for noradrenaline in the present study and it was shown that these contractions were partially blocked by high concentrations of phentolamine (10 pM).…”

“…Uterine tissue from most species contains not only ,B-(inhibitory) adrenoceptors but also a-(excitatory) adrenoceptors (Miller, 1967) and this includes guineapig (Davidson & Ikoku, 1966). Pennefather & Isaac (1967) demonstrated in guinea-pig uterus that, in the presence of propranolol, noradrenaline and adrena-line produced contractions. This was confirmed for noradrenaline in the present study and it was shown that these contractions were partially blocked by high concentrations of phentolamine (10 pM).…”

The Sympathetic Innervation of the Mammalian Ovary. A Review of Pharmacological and Histological Studies

“…Evidence for presence and levels of noradrenaline in ovaries end of the uterus receive the majority of their sympathetic innervation from fibres from the aorticorenal plexus via the ovarian neurovascular pedicle (Kulkarni et al, 1976). In earlier studies with this species, stimulation of the ovarian neurovascular pedicle was found to affect uterine contractility (Pennefather & Isaac, 1967;Isaac et al, 1969), uterine membrane properties (Ngu & Taylor, 1973) and ovarian contractility (Pennefather, 1975). Changes in levels of ovarian steroids, occurring either during and after pregnancy or following hormone administration, have been reported to markedly alter noradrenaline levels in rabbit and guinea-pig uteri, but to have little effect on ovarian noradrenaline (Cardmark et al, 1971, Owman & Sjoberg, 1973.…”