Summary. Prepubertal gilts, having undergone a 7-day period of feed restriction to a maintenance ration, were allocated to one of 4 treatments; restricted feeding at 09:00 and 17:00 h for an 8th day both with (Group RN) and without (Group R) administration of the opioid antagonist naloxone hydrochloride (1 mg·kg−1 at 09:30 h followed by 0·5 mg·kg−1 at hourly intervals for 7 h), or feed to appetite with (Group ALN) and without (Group AL) naloxone administration. Gilts were bled at 10-min intervals on Day 8 from morning to evening feed and plasma LH, FSH and prolactin concentrations were measured by radioimmunoassay. Compared with Group R gilts, Group AL gilts exhibited significantly (P ⩽ 0·05) higher mean and maximum LH concentrations and pulsatility, lower prolactin concentrations (P < 0·05) but no significant difference in FSH secretion. Naloxone significantly depressed the increase in LH after re-feeding (Group ALN) (P < 0·05). Once again there were no significant effects on FSH secretion. Naloxone also significantly depressed prolactin secretion in feed-restricted gilts (P < 0·05). These results confirm that re-feeding of feed-restricted prepubertal gilts stimulates an immediate increase in LH secretion and that this elevation is not mediated via a suppression of inhibitory endogenous opioidergic tone. Rather, naloxone treatment appeared to expose a latent inhibition of LH secretion. The control of LH secretion is distinct from that of FSH in this model. Keywords: prepubertal gilt; realimentation; gonadotrophin; naloxone
Temporal relationships among plasma LH, FSH, metabolic hormones, and glucose concentrations were studied in nutritionally manipulated prepubertal gilts. Twenty-four growth-matched littermate gilts (73.6 ± 1.2 kg) were fed at maintenance for 7 d (d 1 to 7). From d 8 to 14, littermates were divided between two treatments and were either fed twice daily to appetite or continued on feed restriction. Feeding to appetite increased episodic LH secretion during the first 6 h of sampling on d 8 (P < .05). Plasma FSH concentrations were not affected by treatment between d 8 and 14. Nocturnal increases in plasma LH (P < .01) and FSH (P < .002) concentrations were detected in feed-restricted gilts but not realimented gilts. Mean total plasma IGF-I concentrations gradually increased in gilts fed to appetite (d 12, P < .02; d 13 to 14, P < .001). Mean postprandial insulin concentrations were also greater in gilts fed to appetite (P < .01). Treatment differences in mean postprandial glucose concentrations on d 9 and 10 indicate that normoglycemia was established by d 9 in gilts fed to appetite. At slaughter on d 15, numbers of ovarian follicles (P < .01), follicular volume (P < .001), and uterine weight (P < .05) were greater in gilts fed to appetite. In conclusion, uteroovarian responses to realimentation after short-term feed restriction in prepubertal gilts are mediated by enhanced LH secretion. This rapid enhancement of LH secretion in response to dietary repletion might have been mediated by changes in glucose and insulin status. Ovarian responses to gonadotropins may also be potentiated by observed increases in plasma glucose, insulin, and IGF-I. During feed restriction, a distinct diurnal rhythm in gonadotropin secretion was evident.
Folliculogenesis was studied by assessing development of the largest 10 follicles obtained from 10 sows 48 h after weaning and by analyzing changes in plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (PRL) for 24 h before weaning until 48 h after weaning. Follicular diameter, follicular fluid volume, and concentrations of estradiol and testosterone and granulosa cell numbers were determined in all follicles, and 125I-hCG binding to theca and granulosa and maximal aromatase activity in vitro was determined in five follicles/sow. Overall, a significant rise in LH, but not in FSH, occurred at weaning, although in individual sows an increase in LH was not necessarily related to subsequent estrogenic activity of follicles. In 9/10 sows, PRL fell precipitously after weaning. In lactation, LH was negatively, and after weaning, positively, correlated with FSH and PRL. Marked variability in follicular development existed within and between sows. Overall, most follicular characteristics were positively correlated to follicular diameter; however, in larger follicles the number of granulosa cells was variable and unrelated to estrogenic activity, which—together with theca and granulosa binding of hCG—increased abruptly at particular stages of follicular development. Differences in maturation of similarly sized follicles from different sows were related to estrogenic activity of the dominant follicles but not to consistent differences in LH, FSH or PRL secretion. Both the dynamics and the control of folliculogenesis in the sow, therefore, appear to be complex.
Children and infants are apt to swallow a multitude of articles, such as beads, buttons, hair, coins, toys, fruit stones, and so on.For the most part the swallowed objects, depending of course on their size and shape, pass through the alimentary tract and are excreted without causing undue harm to the patient; however, on occasion, even a smooth swallowed, object can be the cause of dire effects, as in the patient whose history is reported here. CASE REPORTEarly in the morning of Boxing Day 1964 a boy aged 2 years 3 months was admitted to the British Military Hospital, Munster, having just vomited approximately 1 pint (0.6 litres) of bright red blood.The only history given by the parents was that he had been off his food and miserable for one week.On examination the child had pale mucosae, a pulse rate of 120 per minute, and was apyrexial.Nothing abnormal was detected in the chest or abdomen.The results of laboratory tests were as follows: haemoglobin, 10 g./100 ml.; packed cell volume, 30%; white blood cell count, 17,000/c.mm.; platelets, 112,000/c.mm.While a possible diagnosis was being considered the parents said that they thought he had swallowed a 10-pfennig coin a week earlier.Radiography of the chest revealed a coin lodged at the level of the tracheal bifurcation.There was no evidence of air in the media- stinum (see Fig.).Blood transfusion was started, and oesophago- scopy was performed.The coin was found at approximately 20 cm.distance from the upper teeth, and was removed without difficulty and without causing bleeding.The coin measured 22 mm. in diameter and was discoloured to a dark green. (The German Federal Government coins of this value consist of a central iron core coated with an alloy of copper and zinc.)
Reproductive status, metabolic state, and carcass composition were compared in prepubertal littermate gilts of 85 kg BW and identical ages after allocation to one of two feeding regimens at 75 kg, either twice-daily feeding to appetite up to 85 kg and then maintenance feeding until slaughter (Group 85AR) or an initial period of maintenance feeding at 75 kg and then feeding to appetite to reach 85 kg (Group 85RA). Other littermates were studied at the start of treatment (Group 75C) and after the initial period of feeding to appetite (Group 85A) or maintenance feeding (Group 75R). In the absence of differences in backfat depth or longissimus muscle area, Group 85RA gilts showed increased follicular development (P < .001) compared with their feed-restricted Group 85AR littermates. Plasma LH (P < .001) and FSH (P < .02) responses to an LHRH challenge differed between these same groups. Feed restriction reduced preprandial glucose, postprandial cortisol, and insulin (P < .05), total plasma IGF-I, and basal and postprandial free triiodothyronine (T3; all P < .001) at all stages of the experiment. Postprandial insulin, pre- (P < .001) and postprandial free T3, and plasma IGF-I (P < .001) increased in response to refeeding (Group 75R vs 85RA). These data indicate that changes in metabolic status can mediate short-term nutritional effects on reproductive function, in the absence of changes in age, weight, and widely used indices of body composition, and also establish the short-term, feed-restricted, prepubertal gilt as an effective model for studying the mechanisms mediating nutrition-reproduction interactions.
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