PubMed Health⌕ Search

Biomedical subjects

K M Kendrick

Publications and source records attributed to K M Kendrick.

At least 73 records · Page 4Linked to original sources
PubMed1991

Importance of progesterone and estrogen priming for the induction of maternal behavior by vaginocervical stimulation in sheep: effects of maternal experience.

The effects of treating ovariectomised nulliparous and multiparous ewes with progesterone and estrogen on maternal behavior with or without vagino-cervical stimulation were investigated. Following 48 h of estrogen treatment there was neither evidence for stimulation of maternal behavior, nor a reduction in aggressive behavior, towards lambs by either multiparous or nulliparous ewes compared with control treatment (injections of the oil vehicle). Following 5 min of mechanical vaginocervical stimulation, the multiparous estrogen-treated ewes showed both positive maternal responses (low pitch bleats, licking, sniffing and approaching the lamb) and a reduction in aggression (butts) and negative behavior (withdrawal from the lamb) towards the lambs, whereas the nulliparous ewes showed only a reduction in aggression and negative behavior. Neither group showed positive maternal responses following vaginocervical stimulation without steroid priming. When the ewes received two weeks of progesterone priming prior to estrogen treatment, both multiparous and nulliparous ewes showed reduced aggression towards, and withdrawal from, the lambs compared to the control condition, but no positive maternal responses apart from an increased sniffing of the lamb. After vaginocervical stimulation positive maternal responses showed by multiparous ewes were significantly potentiated compared to those shown following estrogen treatment alone. Nulliparous ewes remained unresponsive on positive maternal behaviors. These studies show that hormonal priming has little effect in inducing the onset of maternal behavior in multiparous or nulliparous sheep but is an essential prerequisite for vaginocervical stimulation to do so in multiparous animals.

Animals↗
PubMed1991

Importance of vaginocervical stimulation for the formation of maternal bonding in primiparous and multiparous parturient ewes.

The importance of vaginocervical stimulation for the formation of the maternal bond between a ewe and its lambs was investigated by studying the ability of artificial mechanical vaginocervical stimulation to induce adoption of an alien lamb after the selective bond with the ewe's own lambs had been formed. Results showed that for both multiparous and primiparous ewes, 5 min of mechanical VCS (using a hand) was effective in inducing complete acceptance of an alien lamb (6-48 h old) between 6.5 and 7.5 h postpartum in the majority of animals (8/10 multiparous, 8/9 primiparous) without interfering with the bond between the ewe and its own lambs. In a second group of multiparous animals, 6 out of 7 animals were also induced to completely accept an alien lamb between 26.5 and 27.5 h postpartum. It was found that the most critical aspect of the VCS was pressure on, and stretching the neck of, the cervix. Results show that VCS is not only important for the stimulation of maternal behavior, but also for the formation of the selective maternal bond. The ability of VCS to trigger the formation of a new maternal bond extends for at least 27.5 h post-partum.

Animals↗
PubMed1991

Cerebrospinal fluid and plasma concentrations of oxytocin and vasopressin during parturition and vaginocervical stimulation in the sheep.

Simultaneous blood and cerebrospinal fluid (CSF) samples were taken from conscious sheep before, during and after parturition. Concentrations of plasma and CSF oxytocin were significantly elevated during contractions and particularly at birth. Mean prepartum CSF concentrations of oxytocin were around 55% of those found in plasma but postpartum they were up to 2-fold higher than those in plasma. Plasma concentrations of oxytocin were only significantly elevated, compared to prepartum levels, for 15 min postpartum whereas those in CSF were increased for the whole of the 120 min postpartum sampling period. Plasma, but not CSF, concentrations of arginine-vasopressin (AVP) were significantly raised during contractions and birth, and for 15 min postpartum. During the prepartum period CSF AVP concentrations were 67% of those found in plasma whereas at birth plasma levels were 10-fold higher than in CSF. In a separate experiment it was shown that 5 min of mechanical vaginocervical stimulation also stimulated significant increases in CSF and plasma oxytocin concentrations and in plasma vasopressin. Results support previous work suggesting an important role for central oxytocin release in the postpartum induction of maternal behavior and demonstrate that elevated concentrations of oxytocin in the CSF are present for a greater period than in blood. Elevated plasma AVP concentrations during contractions, birth or vaginocervical stimulation may be stimulated by stress associated with these stimuli.

Animals↗
PubMed1991

How the sheep's brain controls the visual recognition of animals and humans.

Visual recognition of objects and individuals is important for humans and many animal species. How does the brain process such visual information and how does experience modify such processing? To answer these questions we have used single-cell, electrophysiological recording techniques to investigate the responses of single neurons in the temporal cortex of the brain of the conscious sheep to visual images of animals and humans. Results show that a small population of these cells responds (latencies less than 180 ms) specifically to projected images of animal and human faces. Different cells respond to 1) faces with horns, and how large the horns are; 2) faces of sheep of the same breed, particularly to socially familiar individuals, and 3) faces of humans or dogs. In general, frontal views of faces (i.e., direct eye contact) are more effective stimuli than profiles or views of the back of the head. Some other cells in the temporal cortex respond to the sight of a human shape, rather than to the face. These latter cells are specialized for visual recognition of the human shape dependent on what actions are displayed (approaching or withdrawing figure), posture adopted (bipedal or quadrupedal), and view presented (front or side). These results provide important information on the complex neural processing of visual recognition of individuals by sheep and suggest that experience may modify sensory processing. Thus, behaviorally important, distinguishing features (such as horns), preferred individuals (socially familiar animals), and potentially threatening individuals (humans and sheep dogs) are specifically coded for, at a sensory level, so that appropriate behavioral or emotional responses can be made with the minimum delay.

Animals↗
PubMed1990

Microdialysis measurement of in vivo neuropeptide release.

The application of the microdialysis sampling technique for in vivo measurement of neuropeptide release is discussed. In vitro recoveries of different microdialysis membranes are described for a variety of neuropeptides (ranging from 400 to 4500 MW) as well as their dynamic potential for measuring external concentration changes. In vivo experiments illustrating the use of the technique for measuring release of oxytocin and met-enkephalin from the brain of the conscious sheep, and vasopressin in the blood of the anaesthetised rat are described.

Animals↗
PubMed1989

Effects of intracerebroventricular infusions of naltrexone and phentolamine on central and peripheral oxytocin release and on maternal behaviour induced by vaginocervical stimulation in the ewe.

The effects of intracerebroventricular infusions of naltrexone and phentolamine on the ability of vaginocervical stimulation to induce maternal behaviour, and plasma and cerebrospinal fluid (CSF) levels of oxytocin, were measured in oestrogen-primed ewes. Results showed that naltrexone, but not phentolamine, significantly inhibited maternal behaviour following vaginocervical stimulation. Naltrexone also prevented the CSF increase in oxytocin following vaginocervical stimulation but was without effect on plasma levels. Phentolamine did not prevent either CSF or plasma increases in oxytocin, following vaginocervical stimulation, but reduced basal plasma levels. Results are discussed in terms of an opioid influence on maternal behaviour which may be mediated through a modulation of central oxytocin release.

Animals↗
PubMed1989

The effects of sodium appetite on the responses of cells in the zona incerta to the sight or ingestion of food, salt and water in sheep.

Single-unit recordings were made from neurones in the zona incerta (ZI) of conscious sheep in response to the sight/visual approach or ingestion of various foods, salts and water. Animals were given parotid fistulae so that effects of sodium appetite, induced by not replacing the sodium lost in the saliva, could be assessed. When sodium depletion was prevented by giving the animals 1% sodium bicarbonate in their drinking water, the majority of cells (45 out of 49) responded most strongly to the sight or visual approach of food compared to water or salt. Four cells responded best to the sight of water, but none to the sight of salt and salt solutions. When a sodium appetite was stimulated, by removing the 1% sodium bicarbonate replacement for 4-6 days, there was a significant change in response profiles of ZI cells. The majority of cells responded most strongly to the sight of salts or salt solutions (35 out of 49) and significantly fewer cells responded most strongly to food (8 out of 49). The number of cells responding primarily to water was not affected (6 out of 49). For 3 cells responding to salts it was shown that, after repeated ingestion of salt over several hours, food became a more potent stimulus. A similar decreased response to foods during sodium depletion, and an increased one to salts, was seen in ZI cells which responded to the ingestion of both solids and liquids. These results show that changing an animal's motivational state produces significant changes in the responses of cells in the ZI responding to the sight or visual approach of substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1989

Visual responses of sheep temporal cortex cells to moving and stationary human images.

Single-cell extracellular recordings were made from temporal cortical neurones in the conscious sheep. The visual responses of these cells to stationary or moving images of humans were investigated. Results from 6 animals showed that a small population of cells responded preferentially to the sight of humans as opposed to other objects or food. These cells did not respond to visual images of the human face, or to individual body parts (legs or arms) or to the smell of a human. The majority of cells showed direction selectivity, with the most effective stimulus being a human moving towards the animal. Cells did not respond differentially to the front and back view of a human although the side view was less effective. The posture adopted by the human was important, since responses were diminished or absent if the human adopted a quadrupedal as opposed to the normal bipedal posture. These results provide evidence for integrated neural processing of both visual recognition, movement and posture in the sheep temporal cortex.

Animals↗
PubMed1989

Microdialysis measurement of monoamine and amino acid release from the medial preoptic region of the sheep in response to heat exposure.

Concentrations of monoamines and metabolites and amino acids were measured in microdialysis samples taken from the medial preoptic area of 5 conscious sheep before, during and after exposure to an ambient temperature of 45 degrees C. Concentrations of dopamine, noradrenaline and aspartate significantly increased, and those of the serotonin metabolite, 5-hydroxyindole-3-acetic acid (5-HIAA), significantly decreased during heat exposure and although panting was induced, body temperature did not change. Concentrations of noradrenaline and aspartate declined and 5-HIAA increased to preheat exposure levels during the 60 min after the ambient temperature was reduced but levels of dopamine and its metabolite, homovanillic acid, remained elevated. Dopamine, noradrenaline, 5-HIAA and aspartate concentrations were not significantly altered by isolation stress and did not show significant changes in the cortex following heat exposure. These experiments provide further support for the proposed roles of dopamine, noradrenaline, serotonin and aspartate in the neural control of autonomic thermoregulatory responses.

Amino Acids↗
PubMed1988

Microdialysis measurement of oxytocin, aspartate, gamma-aminobutyric acid and glutamate release from the olfactory bulb of the sheep during vaginocervical stimulation.

Concentrations of oxytocin and amino acids were measured in microdialysis samples taken from the olfactory bulbs of 5 conscious, oestrogen-treated ewes before, during and after a 10-min period of vaginocervical stimulation. Results showed that vaginocervical stimulation induced significant increases in concentrations of oxytocin, aspartate, gamma-aminobutyric acid (GABA) and glutamate in dialysis samples. Concentrations of other amino acids measured were not affected. These findings show that vaginocervical stimulation produces significant changes in neurochemical release in the olfactory bulbs of sheep. Such changes may be involved in the induction of maternal behaviour of the olfactory recognition of offspring.

Animals↗
PubMed1988

Haemorrhage-induced release of noradrenaline, 5-hydroxytryptamine and uric acid in the supraoptic nucleus of the rat, measured by microdialysis.

Concentrations of monoamines and metabolites and uric acid were measured in sequential 15-min microdialysis samples taken from the area of the supraoptic nucleus (SON) in 9 urethane-anaesthetized rats. A decrease in blood pressure of 40 mm Hg was induced by withdrawing 3-4 ml of blood from an indwelling jugular catheter. This decreased blood pressure was maintained for 30 min and produced a significant rise in the concentrations of noradrenaline (NA) and its metabolite 4-hydroxy-3-methoxyphenylethan-1,2-diol (MHPG) and also in 5-hydroxytryptamine (5-HT) and the purine metabolite uric acid (UA). When blood pressure was returned to normal by replacing the withdrawn blood, the concentrations of NA, MHPG, 5-HT and UA returned to pre-haemorrhage levels within 15 min. No significant changes in concentrations of dopamine and its metabolites were found, and in 7 control animals sampled 1.5-2 mm away from the SON, in the area of the olfactory tubercle, concentrations of NA, MHPG, 5-HT and UA were not significantly altered by haemorrhage-induced decreases in blood pressure.

Animals↗
PubMed1988

Intracranial dialysis measurement of oxytocin, monoamine and uric acid release from the olfactory bulb and substantia nigra of sheep during parturition, suckling, separation from lambs and eating.

Intracranial dialysis was used to measure the release of oxytocin (OXY), monoamines and their metabolites and uric acid (UA) from the substantia nigra (SN) and olfactory bulb (OB) of sheep during parturition, suckling, separation from lambs and eating. Results showed that OXY concentrations increased significantly during parturition, suckling and eating in the SN and during parturition and suckling in the OB. Concentrations of dopamine (DA) increased significantly in the SN during suckling and eating and in the OB during parturition and suckling. The dopamine metabolite, homovanillic acid, also increased significantly in the SN during parturition. Concentrations of the noradrenaline metabolite, 4-hydroxy-3-methoxyphenylethan-1,2-diol (MHPG) and the purine metabolite, UA, were significantly raised during parturition, suckling and separation from the lambs in the SN and increased UA levels were also found during eating. In a separate experiment it was confirmed that OXY was detectable in homogenates of both the SN and the OB. These results show that, in the sheep, OXY and DA release in the SN is associated with maternal and ingestive behaviour whereas similar release in the OB may only be related to maternal behaviour. Release of MHPG in the SN may be associated with maternal behaviour and/or stress.

Animals↗
PubMed1987

Cells in temporal cortex of conscious sheep can respond preferentially to the sight of faces.

To investigate whether the temporal cortex of a nonprimate species contains cells responsive to the sight of faces, a study was made in conscious sheep of the responses of neurons in this brain region to the sight of faces. Of 561 cells from which responses were recorded, 40 responded preferentially to faces. Different categories of these cells were influenced by dominance (presumably indicated by the presence and size of horns), breed and familiarity, and threatening faces such as those of humans and dogs. These results demonstrate that cells that respond preferentially to faces are present in the temporal cortex of a nonprimate species, and that the responses of these cells are influenced by factors relevant to social interaction.

Animals↗
PubMed1987

Intracerebroventricular oxytocin stimulates maternal behaviour in the sheep.

The maternal behaviour of 7 ovariectomized, oestrogen-treated ewes was recorded after intracerebroventricular (ICV) infusions of oxytocin (OT). At weekly intervals 10-min behaviour tests were given starting 1 min after control (saline) or OT infusions. In the ewes' home pens, 5-, 10- and 20-micrograms doses of OT significantly increased the frequency of some or all of the maternal behaviours scored (low-pitch bleats, sniffing, licking and approaching/following the lamb), and 3 ewes allowed suckling attempts. Aggressive (head butts) and negative (withdrawal from the lamb) behaviours significantly decreased in frequency. Vaginocervical stimulation (10 min duration) produced similar effects on these behaviours. When the lambs were removed from the ewes' pens, the ewes exhibited significantly more high-pitch bleats (protest) following OT treatment. When 20 micrograms OT was given ICV in the absence of oestrogen priming, or when it was given intravenously with oestrogen priming, no significant effects on maternal behaviour were seen. Maternal behaviour was also significantly stimulated in oestrogen-treated ewes in a larger, novel testing environment (an enclosed area of field) following 5- and 20-micrograms doses of OT. In an additional experiment in the field enclosure it was found that ewes spent significantly more time near a lamb in a cage following both 5- and 20-micrograms doses of OT. In both experimental settings the high OT doses (10 and 20 micrograms) significantly increased the frequency of feeding although the effect was not dependent on oestrogen priming. These results demonstrate that central OT may play an important role in stimulating maternal behaviour in the sheep.

Animals↗
PubMed1986

Uric acid is released in the zona incerta of the subthalamic region of the sheep during rumination and in response to feeding and drinking stimuli.

The technique of intracranial dialysis was used to sample changes in monoamine metabolite and uric acid concentrations in the zona incerta (ZI) of the subthalamic region of conscious sheep during rumination and in response to the presentation of feeding and drinking stimuli. Sequential 10-min dialysis samples were taken over a 5-h period with stimuli presented at hourly intervals. For each animal, sampling was carried out weekly for 2-3 months. Results from HPLC analysis showed that concentrations of uric acid rose significantly in the ZI, but not in the cortex or peripheral plasma, during rumination, eating, drinking or exposure to the sight or smell of food. No response to control stimuli--loud noise, smell of amyl acetate or sight of a syringe--was found. Concentrations of 5-hydroxyindol-3-yl-acetic acid in the ZI were unaffected.

Acoustic Stimulation↗
PubMed1986

Anteromedial hypothalamic lesions block proceptivity but not receptivity in the female common marmoset (Callithrix jacchus).

The sexual behavior of 8, estradiol-treated, ovariectomized common marmosets was recorded prior to and after bilateral radiofrequency lesions of the hypothalamus. Lesions of the anterior hypothalamus, which extended to varying degrees into the medial hypothalamus, virtually abolished proceptive tongue-flicking and staring displays. Tongue-flicking during copulation also decreased, but the females did not show any significant increase in the number of mounts which they refused or terminated with the exception of one animal which had received more extensive damage to the medial hypothalamus. Significant increases in the frequencies of allogrooming and grooming invitations also occurred after the females had been lesioned. Sexual behavior was not significantly altered in 3 females which received sham lesions. These results provide the first direct evidence for a neuroanatomical distinction between hypothalamic mechanisms which regulate proceptivity and receptivity in primates.

Animals↗