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Biomedical subjects

B Nock

Publications and source records attributed to B Nock.

58 records · Page 4Linked to original sources
PubMed1979

Noradrenergic transmission and female sexual behavior of guinea pigs.

Treatment with the dopamine beta-hydroxylase (DBH) inhibitor U-14,624 (50, 100, or 150 mg/kg) blocked the induction of lordosis behavior be estradiol benzoate (EB) and progesterone (P) in ovariectomized guinea pigs. After treatment with U-14,624 (100 mg/kg), norepinephrine (NE) content of medial basal hypothalamus, preoptic area and cortex was reduced (by 55%) and dopamine (DA) content of medial basal hypothalamus was increased (by 155%) during the period when females treated with EB and P normally display lordosis. Treatment with the NE receptor stimulator clonidine (1.0 mg/kg) restored lordosis behavior in females treated with EB, P, and U-14,624 (100 mg/kg), but the putative DA and serotonin (5-HT) receptor blockers pimozide (1.0 mg/kg) and methysergide (20.0 mg/kg) were ineffective in this respect. Thus, inhibition of lordosis after treatment with U-14,624 appeared to be attributable primarily to a reduction in NE neurotransmission, rather than to increase in DA or 5-HT activity. Because clonidine induced lordosis in females treated with EB, P, and U-14,624, it seemed unlikely that the facilitatory effects of clonidine on lordosis were mediated by activation of presynaptic alpha-adrenergic receptors (i.e. inhibitory NE autoreceptors) rather than by postsynaptic alpha-receptors. In addition, pretreatment with the postsynaptic alpha-adrenergic antagonist phenoxybenzamine (20.0 mg/kg) blocked the facilitation of lordosis by clonidine (1.0 mg/kg) in females primed with EB alone and with EB plus P. Thus, the facilitatory effects of clonidine on lordosis appear to be mediated by activation of postsynaptic alpha-adrenergic (i.e. NE) receptors. The results of this study provide further evidence that NE neurotransmission facilitates the expression of female sexual behavior in guinea pigs.

Animals↗
PubMed1978

Suckling behavior of the infant rat: modulation by a developing neurotransmitter system.

Drugs which alter serotonin receptor activity modified the suckling behavior of 20-day-old rat pups. Suckling could be reinstated in nondeprived pups, which normally do not suckle, by blockade of serotonin receptors with methysergide. Stimulation of serotonin receptors with quipazine inhibited suckling in deprived pups, and this effect was prevented by methysergide pretreatment. This evidence suggests that suckling in weaning age pups is controlled by a serotonergic inhibitory mechanism.

Animals↗
PubMed1976

Behavioural responses to sex steroids of gonadectomized and sexually regressed quail.

The purpose of these experiments was to compare the behavioural and morphological effects of exogenous sex hormones in gonadectomized quail (Coturnix coturnix japonica) with those in quail having regressed gonads as a result of exposure to short days. In Expt 1, male quail were assigned to one of three treatment groups: (1) intact, exposed to 16 h light: 8 h darkness and injected with oil (group 16L); (2) gonadectomized, exposed to 16 h light: 8 h darkness and injected with 2-5 mg testosterone propionate (TP)/day (group 16L-castrated); and (3) intact, exposed to 8 h light: 16 h darkness, and injected with 2-5 mg TP/day (group 8L). Groups 16L-castrated and 8L responded similarly to testosterone, copulating with equal frequency and rapidity after the same number of days of treatment, and also developing proctodeal (foam) glands of a similar size. Only on day 7 of testosterone treatment did the results for these two groups differ. By day 14, the behaviour of both groups resembled that of the 16L birds. In Expt 2 female quail were assigned to the same three treatment groups, except that the hormone treatment was 25 mug oestradiol benzoate/day. Group 8L became sexually receptive sooner than the 16L-ovariectomized quail, but by day 13 both groups had oviducts of similar size, were equally receptive, and were as receptive as the 16L females. The results suggest that the effects of photoperiod on sexual behaviour in this species are mediated largley, if not wholly , by the gonads. They also suggest exposure to short days and surgical gonadectomy are rather similar experimental procedures in the quail.

Animals↗