Health outcomes of children born after IVF/ICSI: a review of current expert opinion and literature.

The Sixth Evian Annual Reproduction (EVAR) Workshop Group Meeting was held to evaluate the impact of IVF/intracytoplasmic sperm injection on the health of assisted-conception children. Epidemiologists, reproductive endocrinologists, embryologists and geneticists presented data from published literature and ongoing research on the incidence of genetic and epigenetic abnormalities and congenital malformations in assisted-conception versus naturally conceived children to reach a consensus on the reasons for potential differences in outcomes between these two groups. IVF-conceived children have lower birthweights and higher peripheral fat, blood pressure and fasting glucose concentrations than controls. Growth, development and cognitive function in assisted-conception children are similar to controls. The absolute risk of imprinting disorders after assisted reproduction is less than 1%. A direct link between assisted reproduction and health-related outcomes in assisted-conception children could not be established. Women undergoing assisted reproduction are often older, increasing the chances of obtaining abnormal gametes that may cause deviations in outcomes between assisted-conception and naturally conceived children. However, after taking into account these factors, it is not clear to what extent poorer outcomes are due to the assisted reproduction procedures themselves. Large-scale, multicentre, prospective epidemiological studies are needed to investigate this further and to confirm long-term health consequences in assisted-conception children. Assisted reproduction treatment is a general term used to describe methods of achieving pregnancy by artificial means and includes IVF and sperm implantation. The effect of assisted reproduction treatment on the health of children born using these artificial methods is not fully understood. In April 2011, fertility research experts met to give presentations based on research in this area and to look carefully at the evidence for the effects of assisted reproduction treatment on children's health. The purpose of this review was to reach an agreement on whether there are differences in the health of assisted-conception children with naturally conceived children. The researchers discovered no increased risk in birth defects in assisted-conception children compared with naturally conceived children. They found that IVF-conceived children have lower birth weights and higher fat under the skin, higher blood pressure and higher fasting glucose concentrations than naturally conceived children; however, growth, development and cognitive function are similar between groups. A very low risk of disorders of genetic control was observed in assisted-conception children. Overall, there did not appear to be a direct link between assisted reproduction treatment and children's health. The researchers concluded that the cause of some differences in the health of children conceived using assisted reproduction treatment may be due to the age of the woman receiving treatment. Large-scale, research studies are needed to study the long-term health of children conceived using assisted reproduction treatment.

Association between impulsivity, reward responsiveness and body mass index in children.

BACKGROUND: Childhood obesity is a major health problem. An association between children's body mass index (BMI) and overeating has been established, but mechanisms leading to overeating are poorly understood. The personality characteristics impulsivity and reward responsiveness may be involved in the tendency to overeat. Impulsivity might relate to overeating through poor inhibition of food intake; reward responsiveness through the rewarding value of food. OBJECTIVE: This study aimed to reveal the relationships between impulsivity, reward responsiveness, overeating and BMI in a sample of 346 Dutch children aged 6-13 years. The BMI distribution in the sample was representative of the BMI distribution in the Dutch pediatric population. METHODS: Impulsivity and reward responsiveness were measured with the Dutch version of the parent-report Sensitivity to Punishment and Sensitivity to Reward Questionnaire for children. Overeating was assessed with the Dutch translation of the parent-report Children's Eating Behaviour Questionnaire. RESULTS: Overeating, impulsivity and reward responsiveness were significantly associated with childhood BMI. Mediation analysis revealed that impulsivity and reward responsiveness equally and significantly predicted BMI indirectly through overeating. CONCLUSIONS: The personality characteristics impulsivity and reward responsiveness predict childhood BMI indirectly through overeating. This suggests that these personality characteristics are risk factors for obesity.

Neurological signs in relation to white matter hyperintensity volumes in memory clinic patients.

PURPOSE: To determine the frequency of neurological signs in a memory clinic population and to explore their associations with white matter hyperintensity (WMH). METHODS: We included patients with Alzheimer disease (AD; n = 210), vascular dementia (VaD; n = 34), mild cognitive impairment (MCI; n = 86) and subjective complaints (n = 153). The presence of extrapyramidal and unilateral signs was assessed from medical charts. On MRI, WMH volumes were extracted automatically. RESULTS: Extrapyramidal signs were found in 10% and unilateral signs in 12% of the patients. Age- and sex-adjusted extrapyramidal signs occurred more often in VaD compared to patients with subjective complaints. Unilateral signs were more prevalent in all groups compared to patients with subjective complaints. Two-way analysis of variance (ANOVA) with WMH as the dependent variable showed a main effect of diagnosis (p < 0.001), but not of extrapyramidal signs (p = 0.62). In contrast, 2-way ANOVA showed main effects of diagnosis (p < 0.001) and unilateral signs (p = 0.001). Furthermore, there was an interaction between these factors (p = 0.04); if unilateral signs were present, patients with subjective complaints and VaD showed more WMH, whereas there was no relation in AD and MCI. CONCLUSION: Extrapyramidal and unilateral signs are common in memory clinic patients, but are only modestly related to WMH.

Insulin resistance and the metabolic syndrome in obese children referred to an obesity center.

OBJECTIVE: The aim of this study was to describe insulin resistance and the metabolic syndrome in obese children and adolescents. SUBJECTS: The cohort consisted of 518 patients, 250 boys, 268 girls, age +/- sd: 11.8 +/- 3.2 years, BMIsds +/- sd: 2.94 +/- 0.5. A standard OGTT was performed. RESULTS: Impaired glucose tolerance was found in 9.4% of the boys and 5.5% of the girls. Impaired fasting glucose was found in 12.4% of the boys and 11.6% of the girls. The metabolic syndrome was present in 13.9% of children of 10 years or older. The proportion in which the metabolic syndrome was diagnosed was essentially not altered when pubertal groups were used instead of age groups. CONCLUSION: Both impaired fasting glucose and impaired glucose tolerance as well as the metabolic syndrome are highly prevalent among obese children and adolescents.

Information processing, attention and visual-motor function of adolescents born after in vitro fertilization compared with spontaneous conception.

BACKGROUND: Adverse conditions during prenatal life are associated with changes in physical and mental functioning in later life, as shown in children born preterm or small for gestational age. While recently in IVF children cardiometabolic differences have been demonstrated, there might also be risks for disturbance in cognitive functions. Therefore, this study examined information processing, attention and visual-motor function in pubertal IVF children compared with spontaneously conceived controls from subfertile parents. Results of these cognitive functions were then related to cardiometabolic measures to explore whether both can be explained by changes in fetal programming due to IVF. METHODS: A total of 139 IVF and 143 control adolescents underwent various neuropsychological tests to measure information processing, attention and visual-motor function. The results were then related to data on blood pressure and glucose levels previously obtained from the same groups. RESULTS: No differences between IVF and control adolescents were found in the various test results for information processing and attention. A slight difference was found between the groups for motor speed, but these scores were within the normal range for the test. No direct relation was found between cognitive measures and cardiometabolic outcome. CONCLUSIONS: Comparison of IVF adolescents and controls revealed no disturbances in information processing, attention and visual-motor function. In addition, these cognitive functions were not directly related to cardiometabolic outcome. Therefore, these results do not support the hypothesis that cognition is influenced by IVF conception or an altered programming of metabolic systems due to IVF, and indicate that cognitive abilities in IVF children, as measured by the tasks assessed, appear to develop normally.

Tracking for underweight, overweight and obesity from childhood to adolescence: a 5-year follow-up study in urban Indonesian children.

AIMS: To assess tracking of body mass index (BMI) of urban Indonesian children from childhood to adolescence and to compare the prevalence of underweight, overweight and obesity in 6- to 8-year-old children from two surveys: years 1999 and 2004. METHODS: A longitudinal study assessing BMI tracking of 308 urban children followed from age 6-8 to 11-13 years and two cross-sectional surveys comparing the prevalence of underweight, overweight and obesity in 6- to 8-year-old children: year 1999 (n = 1,524) and 2004 (n = 510). RESULTS: Childhood BMI determined 52.3% variation of later BMI. After 5.1 (0.6) years the prevalence of overweight and obesity increased from 4.2 and 1.9% in childhood to 8.8 and 3.2% in adolescence. The prevalence of underweight decreased from 27.3 to 18.8%. All obese children remained obese, 84.6% overweight children stayed overweight, 56.0% underweight children remained underweight. In cross-sectional comparison the prevalence of overweight and obesity raised from 5.3 to 8.6% and from 2.7 to 3.7%, respectively. The prevalence of underweight remained constant. CONCLUSIONS: The prevalence of overweight and obesity increases as children grow into adolescence. Overweight or obese children are more likely to remain overweight or obese. Cross-sectional comparison shows, while the prevalence of underweight stays constant, the prevalence of overweight and obesity increases.

[First favourable results of the group education programme Go4it for overweight and obese adolescents]. / Eerste gunstige bevindingen van het groepseducatieprogramma Go4it voor adolescenten met overgewicht of obesitas.

OBJECTIVE: To evaluate the effect of Go4it, a multidisciplinary group education programme for adolescents with overweight or obesity. DESIGN: Uncontrolled intervention study. METHOD: At the obesity outpatient clinic of the Transmural Research and Treatment Centre for Overweight and Obese Children of the VU University Medical Center, Amsterdam, The Netherlands, a group education programme was developed for adolescents (age 12-18 year) who are overweight or obese. Obese adolescents who were referred to the obesity outpatient clinic were asked to participate. During 7 sessions (one session every two weeks) the adolescents were educated on the health consequences of obesity, diet, physical activity, energy balance, improving self-esteem and how to handle bullying and other difficult situations. All sessions were held in groups of 8-10 adolescents. In addition, two sessions were organised for the parents concerning the health consequences of obesity, diet, and physical activity. Body weight and height, glucose tolerance (by an oral glucose tolerance test; OGTT), and insulin resistance were measured at enrolment into the Go4it programme and 6 months later. RESULTS: In total, 93 adolescents (39 boys, 54 girls) were included with a mean age of 3.9 (SD: 1.7) years. Of those, 69 adolescents (74%) attended at least 6 out of 7 sessions of the education programme. Stabilisation or reduction in obesity levels following completion of Go4it was achieved in 51 (74%) of these participants. 50 adolescents had a second OGTT. The BMI standard deviation score (BMI-sds) decreased by 4.3% for boys (p = 0.020) and 3.3% for girls (p = 0.017). Among girls, fasting blood glucose levels decreased by an average of 0.37 mmol/l (95% CI: 0.14-0.60) and insulin concentrations decreased by an average of 299 pmol/l (95% CI: 71-528). CONCLUSION: Participation in the Go4it education programme is accompanied by a stabilisation or reduction in the level of obesity and has favourable effects on glucose and insulin metabolism.

[Undescended testis: current views and advice for treatment]. / De niet-scrotale testis: huidige inzichten en advies voor behandeling.

--Undescended testis (UDT) is one of the most common urogenital abnormalities in boys. --UDT is defined as a testis which cannot be brought into a stable scrotal position. --At present, congenital and acquired forms of UDT are recognised. Congenital UDT is defined as a UDT which has never descended from birth. Acquired UDT is defined as a UDT which has been fully descended in the past. --Congenital UDT should be treated surgically between 6 to 12 months of age. --The treatment of acquired UDT is still disputed. As yet, awaiting spontaneous descent at early puberty seems to be the most rational treatment. --In the Netherlands, the high number of late orchidopexies is due to surgery for acquired UDT. To reduce this high number, the guidelines of the first development conference on 'non-scrotal testis' dating back to 1986 should be revised on several points.

Metabolic implications of GH treatment in small for gestational age.

Fetal growth retardation is associated with decreased postnatal growth, resulting in a lower adult height. In addition, a low birth weight is associated with an increased risk of developing diseases during adulthood, such as insulin resistance, type 2 diabetes mellitus, hypertension, dyslipidemia, and cardiovascular diseases. Children with persistent postnatal growth retardation, i.e., incomplete catch-up growth, can be treated with human GH. The GH/IGF-I axis is involved in the regulation of carbohydrate and lipid metabolism. The question of whether treatment with GH in children born small for gestational age (SGA) has long-term implications with respect to glucose/insulin and lipid metabolism has not been answered yet. In this article, the available data are reviewed.

Influence of intrauterine growth restriction on renal function in the adult rat.

Intrauterine growth restriction (IUGR) has been shown to influence renal development and lead to fewer nephrons. Data on long term renal function after IUGR are limited. We studied the effect on renal function of IUGR in aging rats. IUGR was induced using a model of bilateral uterine artery ligation in pregnant Wistar rats. Renal function was studied at the age of 18 months. In male IUGR rats, estimated glomerular filtration rate was significantly decreased compared to male control rats [1.1 (SD 0.3) 1.7 (SD 0.3) ml x min(-1), p<0.05]. Female IUGR rats showed an increased urinary protein excretion compared with female control rats [84 (SD 73) vs. 12 (SD 13) mg x 24h(-1), p<0.01]. All male rats showed heavy proteinuria (p<0.01 vs. female rats from same experimental group), with no significant differences between the groups. Tubular reabsorption of phosphorus was lower in females, but showed no differences between the experimental groups. In conclusion, IUGR impairs renal function in the rat. It is suggested that a low nephron endowment leads to proteinuria as a sign of glomerular damage, and ends with a decrease in glomerular filtration rate as a sign of glomerular loss.

Weekend versus working day: differences in telemetric blood pressure in male Wistar rats.

Blood pressure (BP) is a frequently monitored parameter in research. Various methods are used to obtain BP values in animal models, but telemetry is the method of choice because it allows for continuous monitoring in conscious and freely moving animals. However, factors due to the animal facility, like activities and sound, can still influence measurements. We, therefore, retrospectively compared BP values in adult male Wistar rats during working hours with values from non-working days. Telemetry devices were implanted according to standard protocol. Values were obtained at the age of 6 and 12 months during working hours (Friday 10:00-16:00 h, lights on 06:00-18:00 h) and compared with data from the average of Saturday 10:00-16:00 h and Sunday 10:00-16:00 h, representing non-working days. Data were available from 12 and 7 rats at 6 months and 12 months of age respectively. Relative differences in heart rate, spontaneous locomotor activity, systolic and diastolic BP were 2.2% (P<0.001), 32.9% (P<0.05), 3.2% (P<0.05) and 3.7% (P<0.05), respectively, with no differences between the age groups. We have shown a significant and important difference between BP values obtained during working hours and non-working days using telemetry in adult male Wistar rats. This phenomenon has implications for the interpretation of BP measurements in animals.

Brain structure, executive function and appetitive traits in adolescent obesity.

BACKGROUND: Children with obesity show differences in brain structure, executive function and appetitive traits when compared with lean peers. Little is known on the relationship between brain structure and these traits. OBJECTIVES: To investigate the relationship between differences in brain structure and executive function and appetitive traits, in obese and lean adolescents. METHODS: MRI was used to measure cortical thickness and subcortical volumes. Executive function was measured by a Stop Signal-and a Choice Delay Task. Appetitive traits were measured using the Child Eating Behaviour Questionnaire. RESULTS: Adolescents with obesity had greater volumes of the pallidum; 1.78 mL (SE 0.03, p=0.014), when compared with controls; 1.65 mL (SE 0.02). In the group with obesity, greater pallidum volume was positively associated with the ability to delay reward in the Choice Delay Task (p=0.012). CONCLUSION: The association between pallidum volumes and Choice Delay Task in obese adolescents supports the hypothesis that the pallidum plays an important role in executive dysfunction in obese children.

Pituitary mRNA expression of the growth hormone axis in the 1-year-old intrauterine growth restricted rat.

Intrauterine growth restriction (IUGR) is one of the major causes of short stature in childhood. Abnormalities in the growth hormone (GH) axis have frequently been observed in children who are born intrauterine growth restricted and GH treatment is effective to improve final height. However, the way that the GH axis is involved is not fully understood. Previously, when investigating the effect of IUGR on the central somatotrophic axis, a hypothalamic effect was discovered with elevated somatostatin and decreased neuropeptide Y mRNA expression levels, whereas serum GH and insulin-like growth factor I (IGFI) were unaltered. These findings were thought to indicate a hypothalamic alteration of the GH axis due to IUGR, probably to compensate pituitary output, thereby normalising peripheral values of GH and IGFI. Therefore, the present study aimed to evaluate the effect of IUGR on the pituitary GH axis in this rat model. Pups from rats that underwent bilateral uterine artery ligation at day 17 of pregnancy were studied. Pituitary glands were collected from 1-year-old offspring for quantitative measurements of GH, GH-receptor (GH-R), GH-releasing hormone receptor (GHRH-R), somatostatin receptor subtype 2 and 5, IGFI and IGFI receptor mRNA levels using a real-time reverse transcriptase-polymerase chain reaction. In addition, liver GH-R and IGFI mRNA expression levels were measured and a radioimmunoassay was performed to determine serum IGFI levels. In the IUGR rat, levels of pituitary GH, GH-R and GHRH-R relative gene expression (RGE) were increased. No differences were found in the RGE level of all other pituitary growth factors, liver GH-R and IGFI, and serum IGFI concentration between IUGR and control rats. The present data show that intrauterine growth failure leads to changes in the pituitary that might counterbalance the effects found previously in the hypothalamus.

[A girl with Cushing's syndrome due to primary pigmented nodular adrenocortical disease]. / Een meisje met het syndroom van Cushing door primaire gepigmenteerde nodulaire adrenocorticale ziekte.

A 12.5-year-old girl with diabetes mellitus type 1 presented with stunted growth and an increase in body weight. Also, her blood-sugar levels were difficult to manage. An adrenocorticotropin-(ACTH)-independent form of Cushing's syndrome was diagnosed. During the dexamethasone-suppression test, a paradoxical increase in urinary-free cortisol excretion was observed, which is a clear indication of primary pigmented nodular adrenocortical disease (PPNAD). The treatment for patients with PPNAD is bilateral adrenalectomy and hormone substitution. PPNAD may be part of the Carney complex, an autosomal dominant multiple neoplasia syndrome. Screening of family members is mandatory. Further investigation for mutations in the gene encoding the regulatory subunit 1A of the protein kinase A (PRKAR1A) may be helpful.

Fetal nutrition and timing of puberty.

Over the last decade growing evidence has been documented on the relationship between intrauterine growth retardation (IUGR) and pubertal development indicating changes in timing and progression of puberty. These changes in pubertal development are part of a growing list of IUGR-related diseases, which includes type 2 diabetes mellitus, cardiovascular disease, short stature and polycystic ovary syndrome. The influence of IUGR on the mechanisms behind the onset of puberty is still elusive. In the absence of prospective studies on gonadotropin-releasing hormone pulse patterns in IUGR children, other markers of pubertal development such as age at menarche in girls and progression of puberty have been employed. We investigated pubertal development and DHEAS levels in children born small for gestational age (SGA) after third trimester growth retardation and children born appropriate for gestational age (AGA). A faster progression of puberty was found in girls but not in boys. DHEAS levels tended to be higher in SGA children than in AGA children. In animal studies using two rat models, growth and onset of puberty based on perinatal undernutrition were also investigated. In one model intrauterine growth retardation was induced by ligation of the uterine arteries (IUGR) at day 17 of gestation and in the other model postnatal food restriction (FR) was induced by increasing litter size after birth until weaning. In both models, the rats showed a persistent growth failure. Onset of puberty was defined by vaginal opening (VO) in female rats and by balanopreputial separation (BPS) in male rats. At onset of puberty IUGR and FR rats had a lower body weight compared to controls, indicating that no threshold for body weight is needed for the onset of puberty. In the IUGR female rats, the onset of puberty was delayed and in the FR female rats the onset of puberty was in time. In both IUGR and FR female rats VO and first cycle were uncoupled. In IUGR female rats, at VO, at first cycle and at the age of 6 months the ovaries showed a decline in number of follicles indicating that intrauterine malnutrition in the female rat has a permanent influence on the growth and development of follicles. In the FR female rats, at VO, the ovaries showed a normal number of follicles but an abnormal maturation pattern. At the time of first cycle and at the age of 6 months normalization in follicle growth pattern was observed. These findings suggest that postnatal undernutrition has a transient influence on follicle growth and development. In male rats, both models showed delayed onset of puberty and impaired testicular function, as shown by decreased testosterone levels. These data indicate that early malnutrition during different critical developmental time windows may result in different long-lasting effects on pubertal development in both humans and rats.

Gonadotropin releasing hormone analogue therapy in children with isolated growth hormone deficiency: final height benefit from postponing puberty?

Although growth hormone (GH) treatment has improved final height prognosis in children with GH deficiency (GHD), adult heights are still disappointing. Final height could be improved by increasing the duration of puberty and in this way increasing total pubertal height gain. Many studies have been published on the effect of gonadal suppression, mostly by gonadotropin releasing hormone (GnRH) analogues, on final height in children with GHD. Because of the different methodologies used in these studies, results are difficult to compare. Both positive and marginal effects on final height have been reported; however, patient numbers are limited. Children with GHD who start puberty at a relatively young age and who have a poor predicted adult height, can benefit from the addition of GnRH analogues. From previous studies, we might conclude that when there is a positive effect, height benefit is marginal. However, additional prospective, randomized controlled trials are needed to further elucidate whether delaying puberty is indicated in children with GHD to improve final height.

Disturbed phase relations in white matter hyperintensity based vascular dementia: an EEG directed connectivity study.

OBJECTIVE: White matter hyperintensities (WMH), a feature seen on magnetic resonance imaging (MRI) and regarded to reflect small vessel disease, can lead to vascular dementia (WMH-VaD). In WMH-VaD, cognitive deficits typically consist of executive function disturbances, and reduced information processing speed, regarded as a result of cerebral hypoperfusion. We aimed to investigate whether this patient group has typical functional differences from controls. METHODS: Resting-state encephalography studies of 17 VaD patients and 17 age- and gender matched non-demented controls were analysed in the delta, theta, alpha1 and 2, and beta frequency bands. Undirected functional connectivity between electrodes was established with the Phase Lag Index (PLI) and directed functional connectivity with the directed Phase Lag Index (dPLI). PLI and dPLI were related to performance in cognitive testing. RESULTS: Mean PLI did not differ between patients and controls. In the control group dPLI showed anterior to posterior phase gradients in all bands except the delta band. In the VaD patient group this pattern was significantly different without a clear directional pattern. No relationship with cognition was demonstrated. CONCLUSIONS: This study shows a clear front-to-back direction of connectivity in non-demented controls. In VaD patients with extensive WMH, this pattern is disturbed. SIGNIFICANCE: Structural damage at the regions of long distance white matter tracts may induce changes in the direction of phase relationships of distinct brain regions.

Pubertal maturation characteristics and the rate of bone mass development longitudinally toward menarche.

To assess risks for osteoporosis and to compare bone mass in different groups of healthy children or children with diseases, it is important to have knowledge of their sexual maturation status during puberty. The aim of our study was to evaluate bone mass formation longitudinally in relation to pubertal maturation characteristics in healthy white girls. We investigated the bone mineral content (BMC) and the bone mineral density (BMD) at different skeletal sites in 151 girls with increasing pubertal stages in relation with their chronological age and with an early or late onset of puberty or menarche and with a slow or fast maturation. Bone mass was measured at the onset of puberty, during puberty, and at menarche. We conclude the following: (1) from midpuberty to menarche, the increase in bone mass formation is highest at all skeletal sites in white girls; (2) early mature girls at the onset of puberty have slightly but definitely lower bone masses at all skeletal sites and at all pubertal stages than late mature girls, whereas the average bone mass formation from the onset of puberty to menarche is similar in both groups; (3) girls with a slow rate of pubertal maturation have lower bone mass values 2 years after the onset of puberty, but at menarche bone mass is similar compared with fast maturers; and (4) it cannot be confirmed that there is an effect of menarcheal age on bone mass values at menarche.

The role of galanin and its receptor in the feedback regulation of growth hormone secretion.

GH controls its own secretion through a mechanism involving short-loop feedback regulation of the synthesis and release of GH-releasing hormone (GHRH). GHRH neurons coexpress the peptide galanin, but the functional significance of this coexpression is unknown. In this study, we tested the hypotheses that 1) galanin gene expression in GHRH neurons is regulated by GH and 2) somatostatin (SS) or GHRH neurons are a target for the action of galanin in the hypothalamus. First, we compared levels of galanin messenger RNA (mRNA) in GHRH neurons between normal male rats and Lewis dwarf rats, which have markedly reduced blood levels of GH. The brains of normal and dwarf animals were processed for detection of galanin mRNA and GHRH mRNA by double-label in situ hybridization. We observed that Lewis dwarf rats had significantly reduced levels of galanin mRNA in their GHRH neurons (P < 0.05). Next, we tested the hypothesis that GH regulates galanin gene expression in GHRH neurons by experimentally altering circulating levels of GH. Three groups of adult male rats were used: 1) intact rats (n = 7); 2) hypophysectomized (hypox) rats (n = 7); and 3) hypox rats treated with 1.5 mg of rat GH (rGH) over a 3-day period (n = 6). At the end of the treatment period, the animals were killed, and their brains were collected and processed for double-label in situ hybridization for GHRH mRNA and galanin mRNA. The signal level of galanin mRNA in GHRH neurons was reduced in hypox animals to less than 10% of that in intact controls (P < 0.0001); whereas, the levels of galanin mRNA signal in GHRH neurons did not differ significantly between the groups of intact and rGH-treated hypox rats. Finally, to determine whether SS or GHRH neurons are targets for galanin, we used double-label in situ hybridization to determine whether either of these populations of neurons express galanin receptor mRNA. A subset of SS neurons in the PeN appeared to express the galanin receptor mRNA, whereas few, if any, GHRH neurons appeared to do so. We conclude that galanin, like its cotransmitter GHRH, is a target for GH action, and we infer that galanin may play a role in the feedback control of GH secretion by exerting a direct effect on SS neurons.